Endocrine System10/24/13 6:47 PM38/31Kingdom Animalia- man is
part of animal kingdom- top groupingAnatomy: study of the parts of
the body and how they relate to each other Gross/Macroscopic: study
of large body parts visible to naked eyeRegional: all structures in
particular region of bodySystematic: structure of the body are
studied by systemsMicroscopic: very small structures that are
viewed by microscopes not the naked eyeCytology: cells
viewedHistology: tissues viewedDevelopmental: structural changes
that occur in body throughout the life spanNeed all organ systems
working in unisonCell form communitiesTissues are made up of group
of similar cells to perform specific roleComparative Anatomy:
compare different structures /organs of the bodyAnatomy Study
success1. observation2. manipulation3. master terms
Anatomical position1. body erect2. feet slight apart3. palms
face forward4. thumbs away from body
Planes/SectionsFrontal: vertical cut= divides body into anterior
and posteriorSagittal: vertical cut=divides body into left/right
partsMidsagittal: cut exactly in mid line that divides body into
EQUAL left/right parts
Anatomy 9/2
-body has to be in anatomical position for dissection -2
cavities in body trunk: dorsal and ventral cavities -see these two
cavities by frontal cut-dorsal: spinal cord and brain-ventral:
larger cavity and subdivided into superior thoracic cavity and
inferior abdominopelvic cavity -ventral is divided by diaphragm
-Thoracic cavity: contains heart and lungs-Abdominal cavity:
contains digestive organs-ventral cavity surrounded by serous
membrane -each organ has its own compartment, which prevents spread
of infection-Compartmentalization allows each organ in the body
cavity to be surrounded by its own membrane -organs in dorsal
cavity are surrounded by membranes called meninges (inflammation of
meninges= meningitis) -dorsal cavity is composed of the cranial
cavity= houses the brain; and the vertebral cavity= houses the
spinal cord
-Ventral Cavity1. Superior Thoracic Cavity2. Inferior
Abdominopelvic Cavity -these are divided by the diaphragm
-membranes called serous membranes surround organs in the ventral
body cavity
Advantages of Compartmentalization1. prevents the spread of
infection from one organ to another in same body cavity2. prevents
interference of the functioning of each organ by neighboring organs
in the same body cavity
9 division of abdominopelvic cavity, but a simpler way is the 4
quadrants (right/left upper and lower)
Abdominal cavity and pelvic cavity blend in so you cant divide
them
Physiology: study of the function of the body parts-structure
defines function1. Systemic physiology: study of the function of
the systems body
11 organ systems in body and all 11 organ systems work together
to sustain the human body, referred to as HOMEOSTASIS
if one organ system isnt working it is homeostatic imbalanceif
one system fails and not repaired other systems will fall apart
11 systems: integumentary, skeletal, muscular, nervous,
endocrine, cardiovascular, lymphatic, respiratory, digestive,
urinary, reproductive
talk about endocrine system when there in a body imbalance
Levels of structural organization1. Chemical- atoms combine to
form molecules2. Cellular- cells made up of molecules3. Tissue-
tissues made up of similar types of cells4.. Organ- organs made up
of different types of tissues5. Organ system- consists of different
organs that work together closely6. Organismal- organisms made up
of many systems
HOMEOSTASIS: balance in the body-established by 2 regulatory
organ systems: nervous and endocrine -nervous system: fast action,
short-lived and localized -endocrine system: generally slow action,
long lasting and global (release hormones in the blood
stream)Homeostasis imbalance=DISEASES-a quick adjustment use the
nervous system
Chapter 2: Chemical Level (lowest level)-looking at structural
organization in the human body (6 structural levels)-Chemical level
is the LOWEST -means were looking at the biochemical reactions
occurring in the body -these chemical reactions are what we refer
to as physiological processes necessary to sustain life
-matter: anything that occupies space and has mass; composed of
elements-atoms=building blocks of all matter-112 elements; most
important: CARBON, NITROGEN, OXYGEN, HYDROGEN
Structure of an atom:1. protons: positively charged- in the
nucleus and is referred to as ATOMIC #2. neutrons: neutral in
nucleus therefore nucleus is POSITIVE3. elections: negatively
charged in outer shells
9/7electrons are located/arranged in the orbits/shells in a
specific mannerfirst shell: max 2 electronssecond shell: max 8
electronsthird shell: max 18 electrons however stable with 8
electronsoutermost shell is VALENCE shellif valence shell does not
contain max number of electrons, the atom is UNSTABLE and therefore
chemical reactiveatoms are not happy unless shells are fullachieve
stability in 2 wayslose electrons or gain electronsinert elements:
atoms with valence shells complete and therefore chemically inert,
unreactiveex: atom with 10 electrons, 2 in first and 8 in 2nd so
therefore stablenoble gaseschemically-reactive elements: atoms in
the elements that have incomplete valence shells and therefore
unstable and chemically reactiveachieve stability thorough forming
CHEMICAL BONDS with other atoms using their valence electrons-
results in formation of molecules and compounds3 types of chemical
bondscovalent bonds: electrons shared between atoms to attain
stability nonpolar: shared equally ex: CO2polar: UNEQUAL; one atom
pulls the shared electrons closer to itself= ELECTRONEGATIVE and
the other atom is ELECTROPOSITIVEoxygen: electronegative;
hydrogen=electropositiveionic bonds: complete transfer of electrons
ex: Na+ Cl-no longer an atom if gain/lose electrongaining/losing
takes energyso is it easier to lose 7 or gain 1 to attain
stability?Atom losing electron is CATION (positive) and atom
accepting electron is ANION (negative)Hydrogen bonds: wear bond
between hydrogen atoms (electropositive) and electronegative
ionsPolar covalent compound Hydrogen bond= weakest; ionic b/c
complete transfer; polar covalent b/c unequal share; nonpolar
covalent b/c equal sharing
Inorganic and Organic CompoundsInorganic: DONT contain carbon
(except carbon monoxide and carbon dioxide)= water, acids, bases,
saltsOrganic: contain carbon that are covalently bondedEx: carbs,
lipids, proteins, nucleic acids
Water- polar covalent moleculeMost abundant compound in body-
70% of the volume of cellsKnown as universal solvent; involved in
all biochemical reactions occurring in bodyHigh heat
capacity-absorbs body heatHigh heat of vaporization: water
evaporates from body using large amounts of heat-cools the bodyFor
cushioning around body organs such as the brain
Acids and BasesAcids: substances that release hydrogen ions
(H+)= protons. Hence, acids are also known as proton donors ex:
HCL, H2CO3Negative log of the H+ concentration= pHThe H+
concentration is inversely proportional to the pH; the higher the
H+ concentration, the lower the pH and vice versaBlood pH is
strictly maintained between 7.35-7.45 (slightly above neutral pH)-
the optimum pH for the actions of enzymes involved in the
physiological processesHigh pH=low acidity, vice versaBases-
substances that accept H+, proton acceptorsEx: HCO3-, NaOHAcid-base
balance is regulated by buffers-chemicals that resist abrupt
changes in pH by binding H+ when the pH falls and by releasing H+
when the pH rises
Salts are ionic compounds that dissociate completely in water to
give cations and anions
Organic CompoundsCarbs: monosaccharide, disaccharides, polylook
at PowerPointHuge role in digestionLipids: neutral fats
(triglycerides) phospholipids, steroids,Proteins: fibrous and
globular proteinsNucleic acids: DNA and RNA
Carbohydrates- hydrated carbonsMonosaccharide=general formula
sweet/soluble in waterMonomers of carbohydratesHexose (CH2O)6-
glucose, fructose, galactosePentose=(CH2O)5- deoxyribose,
riboseDisaccharides- compose of 2 hexose sugars; sweet and soluble
in waterMaltose (grain sugar)- glucose and glucoseSucrose (table
sugar)- glucose and fructoseLactose (milk sugar)- glucose and
galactoseIf lactose intolerant dont have lactase to break down
lactose into the 2 monosaccharidesPolysacchardies are broken up
into disaccharides for digestionLong chains of glucoseStorage form
of glucosestarch in plant cellsGLYCOGEN in animal cellsInsoluble in
water and not sweet
LipidsHydrophobic (insoluble in water)4 typesNeutral
fats=triglycerideMost abundant form of fat in human dietKnown as
Fats when solid and oils when liquids2 types: saturated and
unsaturatedunsaturated: at least one double covalent bond in the
carbon chain; liquid at room temp; plant sourcessaturated: single
covalent bonds exist between all the carbons in the chain; solid at
room temp; animal sources-butterSaturated fats increase LDL which
increases strokes and heart attacksBetter to have unsaturated than
saturated3 types of LipoproteinsvLDL= very low density
lipoproteinLDL= low density lipoprotein= BAD CHOLESTEROLHigh
content of cholesterolHDL= high density lipoproteins=GOODCarry
cholesterol from blood to liver where it will be eliminated from
the bodyNeed cholesterol Maintain the structure of the plasma
membraneSynthesis of the steroid hormones: need these to establish
homeostasis and reproductionThe human body can synthesize 85% of
the cholesterol neededHave to supplement via the diet 15%Any excess
cholesterol in the body carried by LDL will cause plagues to
deposit in the internal walls of the blood vessels: ATHEROSCLEROTIC
plagues= condition of ATHEROSCLEROSISATHEROSCLEROSIS can lead to
hypertension---chronic increase in blood pressureHypertension will
lead to congestive heart failureAtherosclerosis plaque formation is
smaller blood vessels-smallest blood vessels in the human body1.
Cerebral blood vessels2. Coronary blood vesselsPlaque formation in
these blood vessels can cause occlusion of these blood vessels= no
blood flow; tissues served by the occluded vessels dieOcclusion of
cerebral blood vessels= ISCHEMIC STROKES= brain attackOcclusion of
coronary blood vessels= MYOCARDIAL INFARCTION= heart attackThis all
explains why LDL is referred to as the bad cholesterol HDL: good
cholesterolCholesterol transported by HDL to the liverCholesterol
is degraded and eliminated from the bodyLowers cholesterol level in
the blood vesselsDecreases chances of developing atherosclerotic
plaguesPhospholipids: polar head and 2 nonpolar tailsPolar heads=
hydrophilic, tails=hydrophobicMake up the membrane: non polar tails
form the core of the plasma membraneForm micelles to transport
hydrophobic neutral fats in the aqueous environment in the
intestinal lumen Steroids: derived from
cholesterolEicosanoids-derived from arachidonic acids
ProteinsBuilding blocks of proteins are AMINO ACIDSEach amino
acid has an AMINO terminal that can act as a base and a CARBOXYL
terminal that can act as an acidAmino acids are amphoteric
molecules can act as acids and bases20 naturally occurring amino
acidsessential amino acids: must be ingested in the
dietnon-essential amino acids: the cells are capable of
synthesizing these amino acids via a process known as
TRANSAMINATION use amino acids in translation to make proteins4
structure levelsprimary structure: linear polypeptide chain
indicate the type and position of amino acidsecondary structure: 2
typesalpha HELIX coiled: coiled polypeptide chainbeta PLEATED
sheet: polypeptide chains linked side by sidetertiary structure:
secondary structure folded upon themselves to give a compact,
globular molecule---3 dimensionalQuaternary structure: 2 or more
polypeptide chains are held together by disulfide bonds Ex:
hemoglobin; insulin 2 Classes of ProteinsFibrous proteinsExtended/
strand-likeInsoluble in waterForm the framework of all cells:
structural proteinsProvide mechanical and support and tensile
strength as the main building material in the bodyDont denatureEx:
collagenGlobular ProteinsCompact/ball-likeSoluble in water,
sensitive to pH and temp changeChemically active- mediate all
biochemical reactions occurring in the bodyFunctional proteinsEx:
enzymesAre denatured (irreversibly damaged/destroyed) by low pH and
high temperaturesNucleic AcidsRNA: ribonucleic acidContains the
pentose sugar called riboseDNA: deoxyribonucleic acidContains the
pentose sugar called deoxyriboseTranscription Largest organic
compounds in the body
Cellular LevelCell TheoryCell is the basic structural and
functional unit of all organismsAccording to the PRINCIPLE OF
COMPLEMNTARITY of structure and function, the biochemical reactions
occurring in a cell are dictated by the subcellular structures
present in the cellReproduction has a cellular basis200 types of
cells in the body with specific functionsCell diversity: different
shapes/sizesCells that connect body parts, form linings or
transport gases: epithelial cells, fibroblastsCells that move
organs and body parts: muscle cellsCells that store nutrients: fat
cellCell that fights disease: macrophageCell of reproduction :
spermCell that gathers info and controls body functions: nerve
cell3 main parts of cellplasma membrane: defines the boundary of a
cellvery thincomposed of 2 layers of phospholipids (lipid bilayer)
arranged tail to tail with the polar hydrophilic heads exposed to
the aqueous extracellular fluid and the intracellular fluidembedded
membrane proteins and cholesterol are in constant flux :
fluidityFLUID MOSAIC MODELCholesterol insert between the
phospholipids tails to stabilize the plasma membrane= maintains the
integrity of the plasma membrane 2 types of plasma membrane
proteins 1. Integral proteinsspan the plasma membrane exposed on
one surface or both surfaces of the membraneexposed on both
surfaces: TRANSMEMBRANE proteins2. Peripheral proteinsattached to
integral proteins of the phospholipids heads on the cytoplasmic
face of the plasma membraneThese membrane proteins act as
transporters- bring polar molecules across the
membranereceptors-span the plasma membrane for neurotransmitters
and hormonesenzymatic activityintercellular joiningcell-cell
recognition: glycoprotein act as ID tags that are specifically
recognized by other cellson the extracellular surface of cells,
accumulation of glycoprotein and glycolipids form a structure
called the GLYCOCALYXglycoprotein= membrane protein+
carbohydratesthe pattern of carbohydrate arrangement is unique to
each cell type. Hence, the glycocalyx acts as a molecular
(biological) marker for cell-cell recognition EX: the glycocalyx on
the surface of the ovum (egg) is recognized by the spermsperm
approaches the ovum to bindSudden changes in the pattern of the
carbohydrate arrangement in the glycocalyx indicates the cells are
turning cancerous3 Membrane Junctionsexist between adjacent cells
in a tissue1. Tight junctionintegral proteins of adjacent cells
fuse to form an impermeable junction between cellscan only take
things acrossEX: blood brain barrier between the blood in
capillaries and the neurons in the brain---BBB prevents the
exposure of these neurons to toxinsEX: cells lining the gastric
wall (tight junctions prevent seeping)2. Desmosomelinker proteins
inserted in the space between the adjacent cells to hold the cells
togetherprevents cells from pulling apart under stressANCHOR CELLS:
ANCHORING JUNCTIONAbundant in areas of the body subjected to
stressPresent in epidermis of the skinEX: heart wall: cardiac
muscle3. Gap junctiontransmembrane proteins called CONNEXONS:
hollow cylindrical tubes that connect adjacent cellsconnexons act
as channels to allow for the rapid transfer of ions for the rapid
transfer of electrical current from cell to cellreferred to as
COMMUNICATING junctionspresent in cells that are electrically
coupled and contract as a single unit: functional
syncytiumelectrically coupled tissue functions as a single unit:
all cells contract almost at the same timeex: smooth muscleMEMBRANE
TRANSPORT: Plasma membrane is a selective barrierPassive process:
substances cross the membrane without any energy input1. Diffusion3
subtypesSimple diffusion: hydrophobic/nonpolar/ lipid soluble
substances easily diffuse through the lipid bilayer of the plasma
membrane down their concentration gradientdiffuse from areas of
HIGHER concentration to areas of LOWEREX: O2 diffuses from the
fluid outside the cell into the cell and CO2 diffuses from cell
interior to the cell exterior Facilitated diffusion: involves
carrier proteins: integral proteins imbedded in the plasma
membraneLipid insoluble/polar/hydrophilic substances are carried
across the lipid bilayer of the plasma membraneEX: glucose and
amino acids use facilitated diffusion to move into the cell Carrier
proteins: once they are engaged in transporting the substance;
transport maximum is reached: SATURATION: represented graphically
by the sigmoid curveOsmosis: water will move from an area of lower
solute concentration to an area of higher solute concentration2.
Filtrationa passive process- no energy inputmovement of solution
from area of higher pressure to area of lower pressure; down a
pressure gradient Active Processes: cell provides energy (ATP)
required to move substances across the membrane1. Active transport:
movement of solutes/ions from area of lower solute concentration to
area of higher solute concentration (against concentration
gradient)mediated by carrier proteinsexhibits saturation and
specificity SOLUTE PUMPING2. Vesicular transportexocytosis :
movement of substances out of the cell (enclosed in vesicle)
secretory cells use exocytosis to secrete their content to the
cells exterior ex: hormones and enzymes are secreted this
wayendocytosis: movement of substances into the cellphagocytosis:
movement of solid particles from the exterior into the interior;
enclosed in vesicles: PHAGOSOMESlysosomes (cytosplasmic organelles
that contain powerful digestive enzymes called LYSOZYMES) fuse with
the phagosomes to digest it and its contentscells that perform
phagocytosis: PHAGOCYTESphagocytes are present in the immune system
(destroy pathogens: disease causing micro-organisms)ultimate
phagocyte: MACROPHAGEmay be clumps of bacteria or cell debrisnot
all cells are capable of thispinocystosis: movement of solution
into cells by enclosing the solution in vesiclesbulk phase
endocytosisall cells go through pinocytosis to obtain
nutrientsreceptor-mediated endocytosis: receptors bind to specific
substances and are taken into the cell LDL binds to LDL receptors
on the plasma membrane of steroidgenic cells (cells that produce
steroid hormones)Exhibits specificity and saturationEndocytosis and
ExocytosisTrancytosis: Movements of substances enclosed in caveolae
into a cell, across the cell and released on the opposite side of
the cell via exocytosisVesicular Trafficking: Intracellular
movement of substances in coatmer- coated vesicles from organelle
to organelle within the cell Resting Membrane Potential (RMP)Plasma
membrane is very receptive to potassium ionsMore potassium ions
inside and more sodium outsideMore potassium ions leave the cell
than sodium ions coming in because plasma membrane is more
permeable to potassium ionsTherefore cytoplasmic surface is
negativeSeparation of charges causes the RMPTONICITYMovement of
water in and out of cells can shape or tone of cellsIsotonic:
concentration of solution inside and outside of the cells is the
same; same amount of water moves in and outs; shape remains the
sameHypertonic:Hypotonic: placed in solution with a lower
concentration than solution inside cells; water moves via osmosis
into the cells- cells swell and eventually burstCytoplasm- the
interior of the cell between the plasma membrane and the nucleus;
contain cytoplasmic organellesContains cytosol, cytoplasmic
organelles and inclusions (not all cells have these)Membranous
organelles MitochondriaDouble membrane enclosing a fluid matrix
(outer and inner membrane)Inner membrane contains cristaeContains
own DNA: self-replicating organelleERSmooth ER: lipid transport,
lipid metabolism, lipid synthesissteroidgenic cells have prominent
smooth ER which is the site of the synthesis of steroid
hormonesspecialized smooth ER is muscle cells is called
sarcoplasmic reticulum which is specialized to store and release
calcium ions (ca2+)enzymes on smooth ER are involved in
detoxificationliver cells (hepatocytes) and kidney cells have
prominent smooth ER--- site of detoxification of drugsRough
ERexternal surface is studded with ribosomes ( Bound ribosomes)
these ribosomes synthesize the plasma protein and secretory
proteins. Rough ER is therefore abundant in secretory cells such as
liver cellsRough ER is referred to as the Membrane factory because
the synthesis of integral proteins and phospholipids in plasma
membranes is associated with the rough ERGolgi apparatusTRAFFIC
DIRECTOR OF CELLComposed of stacked/flattened membranous
sacsReceives proteins/lipid from rough ER: these proteins may be
modifiedAll proteins received are packaged into vesicles and tagged
for their destinations3 types of vesicles1. Secretory vesicles:
contains proteins released via extocytosissecretory cells---secrete
proteins---will have prominent rough ER and golgi apparatus;
abundance of bound ribosomes2. Vesicles that contain integral
proteins and lipids destined for the plasma membrane to be
incorporated into the plasma membraneVesicles containing powerful
digestive enzymes that remain in the cell= LYSOSOMESLysosomes
(spherical membranous organelles)Vesicles formed by the golgi
apparatusbud off from golgiContain powerful digestive
enzymes(LYSOZYMES) that digest vesicles and biological
moleculesDigest nonuseful tissues, worn-out organelles, worn-out
cellsDigest phagosomes hence, lysosomes are abundant in
phagocytesStimulate glycogenolysis : break down of glycogen into
glucose 6 phosphates which will then enter into the glycolytic
pathwayLysozymes in lysosomes stimulate bone resorption (bone
breakdown) to release stored calcium back into the bloodDEMOLITION
CREWShort life span (die after 2 years)PeroxisomesAlso
sphericalMembranous sacs that contain powerful enzymes that
neutralize harmful free radicals (very unstable and seek to bond to
other molecules to achieve stability)Free radicals are thought to
play a role in the aging process2 enzymes: Oxidases and
Catalasesmore peroxisomes you have, the betterFree radicals
(harmful) + Oxidases Hydrogen Peroxide( harmful)Hydrogen peroxide +
catalase waterNonmembranous organellesRibosomesFree Ribsomes: float
freely in cytosol and synthesize proteins that stay in the
cellBound ribosomes: bound to surface of rough ER and synthesize
proteins that are transported to the plasma membrane and exported
out of the cellCytoskeletoncell skeleton- support other cytoplasmic
organelles and allow for movementsrod-like structures3 types based
on function1. Microtubules: largest diameter= 25 nm widemade up of
globular proteins called TUBULINSTubulins are assembled into
microtubules in the CENTROSOME: microtubule organizing
centerCentrosome contains 2 centrioles at right anglesEach
centriole is composed of 9 triplet array of microtubulesCentrioles
sprout spindle fibers required for cell divisionCentrioles form 2
types of cell extensions: CILIA AND FLAGELLUMCilia: cellular
extensions that occur in large numbers on the apical (exposed)
surface of cellsCilia beat to create a current to move substances
across the surface of the cellsFlagellum: a single, longer cellular
extension that beats to propel the cell it extends from: ONLY
SPERMStructural difference between cilia and the flagellum: cilia
has shorter extension and occurs in large numbers; flagellum has
longer extension and only one per cellserve as tracks to transport
intracellular substancesinvolved in vesicular trafficking 2.
Intermediate Filaments= 10 nmmost stable type of cytoskeletontough,
insoluble fibrous fibersprovide tensile strength to cells by
resisting pulling forces placed on the cells3. Microfilaments:
smallest diameter= 7 nm arrangement is unique to each cellinvolved
in formation of cleavage furrow during cytokinesisinvolved in the
changes of the plasma membrane during endocytosis and
exocytosisNucleus: contains the genes which control activities of
the cell A cell with one nucleus = UninucleateA cell with many
nuclei = MultinucleateA cell without a nucleus = Anucleate3 main
regions:Nuclear envelope (membrane)Double-layered selective
membraneSimilar to plasma membrane but the plasma membrane has
GLYCOCALYX and the nuclear envelope has nuclear poreNuclear pores
allow molecules to enter/exit the nucleusRNA move from nucleus to
cytoplasmNucleolusSynthesizes ribosomal RNA (rRNA)Each ribosomal
subunit is composed of rRNA and proteinrRNA is exported via the
nuclear pores into the cytoplasm where the rRNA combines with
protein to form the small and large ribosomoal subunits Functional
ribosome: involved in protein synthesis will be the small subunit +
the large subunitEach subunit is made up of rRNA and
proteinNucleoli are prominent in cells producing large amounts of
proteinIndicate 3 structures in the cell that will be in the
abundance or prominent in the secretory cell: A) prominent rough
ERB) high levels of bound ribosomesC) high levels of nucleoliDNA is
double-helix; RNA is single strandedDNA is A-T G-C; RNA is A-U
G-CDNA has deoxyribose; RNA has riboseChromatinComposed of
structural units called NUCLEOSOMESEach nucleosome consists of 8
histone proteins and threadlike DNA wrapped around the 8 histone
proteins Function of the histone proteins in chromatin1) packing
the delicate threadlike DNA to prevent DNA from twisting or
breaking2) regulate the activities of the DNAwhen DNA is packaged
with histone proteins the DNA is in its inactive coiled form called
heterochromatindissociation of the histone proteins from DNA
results in the DNA assuming its ACTIVE extended form called
EUCHROMATINDNA replicationTranscriptionDNA a type of nucleic acid2
types of nucleic acidsDNARNAThe structural unities for nucleic
acids are NUCLEOTIDESPentose sugarNitrogen containing basePhosphate
groupNitrogen containing bases in DNA A,G,C,TNitrogen containing
bases in RNA A,G,C,UCovalent bonds between A-T, G-C or A-UCell
Cycle2 major sequential periodsInterphase G1, S, G2Cell
DivisionMitosisCytokenisisInterphase 1st major phase of the cell
cycle composed of 3 sequential subphases G1growthCell is active in
producing proteinsReplication of the centrioles (in the centrosome)
begin toward the end of the G1 phaseLongest phase in
interphaseSgrowth and DNA synthesisMain event DNA replicationEnds
with 2 identical copies of the DNA each will be passed on to each
of the daughter cells formed after cytokinesisDNA
replicationEnzyme: HELICASE untwists and unwinds the double helical
DNA into 2 polynucleotide chains that act as templates for the
synthesis of 2 complementary polynucleotide chainsThe area of the
separation on the double helical DNA REPLICATION BUBBLEThe Y-shaped
end of the replication bubble REPLICATION FORK1st DNA template---
complementary polynucleotide chain2nd DNA template--- complementary
polynucleotide chainat the end of DNA replication you will have 2
identical DNAeach DNA is composed of the template (old
polynucleotide chain) and a complementary polynucleotide chain
(newly synthesized) DNA replication is referred to as
SEMI-CONSERVATIVE REPLICATIONG2Synthesis of proteins that include
proteins that initiate/ maintain cell divisionSuch as cyclin,
cyclin-dependent kinase (cdK) and M-phase promoting factor (MPF)GO
PROTEINS They give the cell the go ahead to enter into
mitosisReplication of centrioles is completed Cell grows by
increase in size due to protein synthesis that occurs during all
the subphases of interphaseMitosis: 4 phasesCompare and contrast
prophase/telophaseHyperplasia: growth by increase in cell
number=mitsosisHypertrophy: growth by increase in cell
sizeCytokinesis: cytoplasmic divisionCancer CellsNeoplasm:
excessive proliferation of cells considered abnormalBenign- grows
slowly and its confined to one locationMalignant-CANCER- grows fast
and aggressively; metastasizes into other organs1st prevent DNA
replication b/c without replication (S phase) there will be no
reproductionInhibit the actions/production of the GO
PROTEINSSUMMARY:Interphase EUCHROMATINProtein synthesis and DNA
replication: ACTIVE DNACell division MITOSISInactive form of
DNAHETROCHROMATINFurther condensed into short bar-like structures
called CHROMOSOMEPrevent entanglement, twisting and breakage as
they move in ANAPHASEProtein Synthesis 2 sequential events,
transcription and translationTranscription (in nucleus)Only use one
strand of DNA as the templateDNA is transcribed in pre-mRNA and the
pre-mRNA is edited (introns removed, leaving exons) into mRNAThe
helicase untwists and separates the 2 DNA polynucleotide chains1
chain becomes the template strand and the other becomes the coding
strandThe pre-mRNA (primary transcript) is synthesized from the
template using the law of complimentary of base pairingsThe
template presents GTCAGT then pre-mRNA is CAGUCAAt the end of
transcription you have the pre-mRNA which consists of introns and
exonsIntrons do not specify amino acids; EXONS specify specific
sequenceAfter transcription the pre-mRNA is edited to give the mRNA
(only exons; introns are spliced out)mRNA leaves nuclear poreCoding
strand (DNA polynucleotide chain not used in transcription) has the
same base sequence as pre-mRNA, except a T in the coding strand is
replaced by a U in the pre-mRNATranslation (in cytoplasm)Occurs in
the cytoplasm and involves 3 types of RNAmRNArRNA forms part of the
ribosometRNA transfer RNA; 3 base sequence attached at 1 end and an
amino acid at the other end3 base sequences in mRNA is referred to
as codon3 base sequences in the tRNA anti-codonTriplet = 3 base
sequence in DNA is the same as the anti-codon except t in the
triplet is replaced by uWhat is the significance of the redundancy
in the genetic code?It avoids problems that occur from
mutationsBase changes at the 3rd base has little impact on the
protein but if it is the first base then it can code for an
entirely different amino acid20 naturally occurring amino acids but
60 codons which takes care of minor mistakes that can occur during
transcription but will not affect the type of amino acid
specified
EXAM 1 NOTES10/24/13 6:47 PM
Tissues4 primary tissues: Epithelial, Connective, Muscular,
NervousEpithelialCharacteristics:Polarity: lower/attached basal
surface, upper/free apical layerA vascular: lack blood
vesselsSupported by a basement membrane: double layeredSuperior
basal lamina abutting the epithelial tissueDeeper reticular lamina
abutting the underlying connective tissueConnective tissue
underlies/support itVascular and provides nutrients to the
overlying a vascular epithelial by diffusing through the basement
membraneHigh regenerative capacityInnervatedMembranous v.
GlandularMembranous= covering/liningSimple- composed of a single
layerSimple Squamous: (flattened-like cells with a disc-shaped
nucleus)Single layer of squamous cellsLocation:Respiratory membrane
in the lungsFiltration membrane in the kidneysLines structures in
the circulatory systemCardiovascular and lymphatic Specifically
referred to as the ENDOTHELIUMForms part of the serous membrane
where it is specifically referred to as the MESOTHELIUMFunction:As
part of the mesothelium is secretes the serous fluid that acts as a
lubricant to reduce friction as these structures in the ventral
body cavity move Diffusion of gases in the lungs (respiratory
membrane)Filtration in the kidneys (filtration membrane)As the
endothelium it presents a slick, frictionless surface for the flow
of fluids: blood and lymph in the lymphatic systemSimple Cuboidal:
(box-like with centrally spherical nucleus)Single layer of
cube-shaped cells with a centrally placed nucleiLocation:Proximal
convoluted tubules (PCT) and in the distal convoluted tubules (DCT)
in the kidneysSurface of the ovaries as the outer membrane
surrounding ovaries where it is specifically referred to as the
GERMINAL EPITHELIUMFunction:Reabsorption and secretionSimple
Columnar: (long columns; elongated nucleus towards the basal
surface of the cell)Single layer of tall cells with a elongated
nuclei placed closer to the basal surface2 typesCiliated: in
respiratory tract and uterine (fallopian tubes in the female
reproductive tract)Function: PROPULSION: cilia beat to create
current that moves substances undirectionallyRespiratory tract:
propulsion of mucusUterine tubes: propulsion of ova (eggs) or
zygotesNonciliated: in the lining of most of the structures in the
gastro intestinal tractFunction: SECRETION of enzymes required for
the chemical digestion of nutrients (food) in the GI
tractPseudostratified columnarSingle layer of columnar cells of
different heights with their nuclei also appearing at different
heights giving the false impression of stratification 2
types:Ciliated: have cells endowed with GOBLET CELLS: secrete mucin
that when interacts with water makes mucous Specifically referred
to as the RESPIRATORY EPITHELIUM: most of the structures in the
respiratory tract are lined with thisNonciliated: lines the
sperm-carrying duct in the male reproductive system such as the
epididymis and vas deferensPhagocytize sperm that are not ejected
through the urethral orifice Stratified: composed of at least 2
layers of epithelial cells: named the epithelial cell type based on
the apical surface of the epithelial Stratified squamous: several
layer of epithelial cells with the cell type on the apical surface
being flattened with disc-shaped centrally placed
nucleiKeratinized: the cells on the apical surface are DEAD cells
impregnated with a tough fibrous protein called keratinLocation:
epidermis of the skinFunction: abrasive-resistant and can withstand
wear and tearEpidermis acts as a physical barrier against pathogens
Nonkeratinized: apical cells are not filled with keratincells are
alive Location: forms the superior part of the mucous membrane
which lines the tracts of the bodyopenings to the exterior. The
exit and entry points of the tracts are lined with mucous membrane
with the nonkeratinized stratified squamous epithelial forming part
of it GI Tract:Entry point: oral cavityExit point: anal cavityBoth
cavities are lined with mucous membrane composed of nonkeratinized
stratified squamous epithelial over connective tissueStomach:
lining is mucous membrane composed of simple columnar epithelium
over connective tissueFunctions: abrasive-resistantStratified
cuboidal and columnarMain function: protectionRare in human
bodyLocation: duct of multicellular exocrine glands such as sweat
glands, salivary glandsFunction: stratification confers PROTECTION:
interlay surface of ducts because the ducts carry secreted products
from the glands, these epithelia are said to be involved in
secretionTransitional epithelium Location: lines structures in the
urinary system that transport stored urineUreters: slender-like
tubes that extend from the kidneys to the bladder; transport urine
from kidney to bladderBladder: storage organ for urineSuperior part
of the urethra: drains urine from the bladder to the
exteriorFunction: the transitional epithelia undergoes a TRANSITION
from 6 layers with cubodial apical cells to 3 layers with flattened
squamous-like cells as these structures fill with urine Undergoes a
TRANSITION to increase the capacity of these structures to
accommodate urineGlandular: epithelial cells form the secretory
portion of the duct system of multicellular exocrine
glandsEndocrine: secretes their products directly into
extracellular fluidExocrine: secrete products onto bodys surface2
types: Unicellular and MulticellularUnicellular goblet cells (only
unicellular) which are scattered within the membranous epithelial
that secrete mucin (mucin +water=mucous)Multicellular: 2 types of
classificationStructural ClassificationDuct System (simple glands:
unbranched duct; compound glands: branched ducts)Shape of the
Secretory portionFunctional Classification=mode of
secretionApocrine: apex of the secretory cell pinches off to
release accumulated products (no example in human body)Merocrine:
secretory cell undergoes exocytosis to release productsHolocrine:
secretory cells ruptures to release its accumulated products (ex:
sebaceous glands)Connective tissue1. All have a common origin:
derived from embryonic tissue: MESENCHYMEExhibit a degree of
vascularityComposed of 2 parts: nonliving and living
portionNonliving: extracellular matrix= ground substance and
fibers3 fiber typescollagen fibers: white fiberselastic fibers:
yellowreticular fibersGround substanceIntestinal fluidAdhesion
moleculesProteoglycans composed of glycosaminoglycens (GAGs)The
more GAGs in the ground substance= the consistency of the matrix
solidLiving portion: cells that are derived from mesenchyme and
they produce the connective tissueFibroblasts: produce connective
tissue proper (gel-like matrix)Chondroblasts: produce cartilage
(semi-solid matrix)Osteoblasts: produce bone tissue (solid
matrix)Hematopoietic stem cell: produce blood cellsConnective
tissue properLiving portion: secreted by FIBROBLASTSConsistency of
the ground substance gel-like2 subclasses (all of these will be
secreted by fibroblasts)LooseAreolar: supports structures in the
body hence, is also referred to as the PACKING MATERIAL of the
bodyLocation: Underlying epithelial tissue in mucous membrane where
the areolar CT is given a proper name: LAMINA PROPRIAThe papillary
layer of the dermis (of the skin) is composed of areolar CTHighly
vascularized Function: 1. Support other tissue by providing
nutrients2. By virtue of the presence of the immune cells
(macrophages, blood cells) in the areolar CT, its involved in the
immune response 3. Excess interstitial fluid is held back inside
areolar CT excess interstitial fluid in areolar CT is known as
EDEMAAdipose: adipose cells= adipocytes, store triglycerides in the
adipose CTLocation: surrounds and supports all structures in the
bodyFunction:1. For cushioning protects structures against trauma
2. Holds structures in their correct anatomical positions 3.
Provides storage form of concentrated energy1g of glucose= 4 kcal1g
of proteins= 4 kcal1g of fat=9 kcalReticular: Found in lymphoid
organs (lymph nodes, thymus, spleen) that contain reticular CT that
form a network inside these organs called the STROMALymphoid cells
reside and proliferate in the stroma to provide immunity Dense:
fibrous CT because of the fiber content Regular: bundles of
collagen fibers arranged in an orderly, regular fashion (all fibers
face in one direction)-->Can withstand stress applied in only
one direction Location: Tendons: connect skeletal muscle to
bonesLigaments: connect bones to joint sitesAponeuroses: sheet-like
tendons that connect muscle to muscles over skeletal structures
Poorly vascularized (tendons take a longer time to heal)not taking
enough nutrients in as fast as you can to repair Irregular:
contains bundles of collagen fibers arranged in an irregular
fashion (fibers face in all directions) withstand stress applied
Highly vascularized and provides nutrients to the structures it
surrounds/supports Elastic: dense regular CT but with elastic
fibersFunction: exhibit the stretch-recoil propertiesLocation:
ligamenta flava which connect adjacent vertebraeCartilage: secreted
by chondroblasts; semi-solid matrix due to high levels of GAGs; a
vascular; surrounded by PERICHONDRIUM (composed of dense irregular
CT) that provides nutrients to the cartilage3 typesHyaline: most
abundantEmbryonic, Epiphyseal, Articular and Costal
cartilageStructureAppears glassy under light microscopeSmooth
appearance without obvious bundles of collagen fibers Shallow
concavities called LACUNAE inside the semi-solid matrix matured
chondroblasts called chondrocytes reside in the lacunae
LocationMost of the embryonic skeleton is composed of hyaline
cartilage after ossification, some of the hyaline cartilage
persists as 1) epiphyseal plates located at the junctions of the
epiphysis and the diaphyses of the long boneEpiphyseal plates allow
for longitudinal bone growth during childhood and
adolescence.Toward the end of adolescence, the epiphyseal plates
will close= EPIPHYSEAL PLATE CLOSURERemnants of the epiphyseal
plates are the EPIPHYSEAL LINES=present in the long bones of
adultsConsequence of the epiphyseal plate closure=height is
determined2) Articular cartilage thin layer of hyaline cartilage
that caps the ends of epiphysesArticular cartilage acts as shock
absorbers cushions the ends of the epiphyses to protect against
wear-and-tear as bones move at joint sites3) Costal cartilage
connect ribs to the sternum costal cartilages act to anchor the
ribs anteriorly Elastic: have more elastic fibers in matrix than
hyaline cartilagePredominant fiber type=ELASTIC FIBERS appear as
tangles in the matrix.Location: 2 areas in the human
bodyEpiglottis: covers the laryngeal opening during swallowingPinna
(external ear) directs sound waves into the external auditory
canalFunction: allows for these structures to be stretched under
stress; and to recoil when the stress is released to assume their
original shape/size stretch-recoil properties of elastic
structuresFibrocartilagePredominant fiber type- collagen
fibersBundles of collagen fibers alternating with row of lacunae
continued chondrocytesLocation:Intervertebral discs located between
2 adjacent vertebrae in the vertebral column; act as
shock-absorbers to protect the surfaces of the vertebrae together
with elastic CTThe fibrocartilage allows for the vertebral column
to be flexiblebending Pubic symphysis joins the 2 hip bones (os
coxae) hence, the pubic symphsis acts as a jointThe fibrocartilage
allows for the hip bones to be slightly stretched to increase the
pelvic brim to allow for the passage of the fetus during
parturition (labor)= flexibility Menisci padsFibrocartilage
inserted into synovial joints to improve the fit of the bones at
the synovial joints decrease wear and tearBone (osseous) Tissue:
cell type secreted bone tissue= OSTEOBLASTSConsistency of the
matrix= solid wit lacunaeMature osteoblasts called osteocytes
reside in the lacunaeSolid MatrixOrganic matrix: osteoidGround
substance and fibersPredominant fiber type collagen fibersGround
substance increase GAGsInorganic matrixComposed of calcium
phosphate crystals, which harden the matrix to make it solidCalcium
phosphate crystals embedded in bone matrix hydroxyapatitesLocation:
located in bonesFunction: basically the function of bones (the
organs)Blood: fluid matrix plasmaLocation: blood vesselsTransport
respiratory gases and nutrients and wastesNervous Tissue 3rd
primary tissueComposed of 2 cell typesNeurons: generate and
transmit impulses (electrical signals)Supporting Cells: non
conducting cells meaning they do not generate/transmit impulses6
typesStructure: 3 regionsCell body contains the nucleus and acts as
the biosynthetic region (for protein synthesis)A centrosome
(contains 2 centrioles at right angles) is absent hence, neurons
are amitotic not capable of undergoing mitosisDendriteAxonEach
neuron has only one axon and may have at least 1 dendrite a neuron
can have several dendritesLocation: Nervous tissue forms most of
the structure in the brain, spinal chord, and nervesFunction:
generate and transmit impulses to other neurons or to effector
cells such as skeletal muscle fibersMuscle Tissue 4th primary
tissue typeOrganized with connective tissue, blood vessels, nerves
to form organs called muscleSkeletal Muscle each cell is referred
to as a fiber because they are long and cylindricalComposed of long
cylindrical cells elongated cells are referred to as skeletal
muscle fibersMultinucleateoccurs when mitosis occurs without
cytokinesis or from the fusing of several cellsLength= 30 cm
longWhen organized to form skeletal muscle it attaches to bone
(both directly and indirectly)Combines with connective tissue,
blood vessels, and nerves to form organ skeletal muscleStriated
Structure: long, cylindrical, referred to as fiberLocation:
organized with blood vessels and nerves to form skeletal muscle
structureFunction: under voluntary control; for the voluntary
contraction to cause body movement and facial expression skeletal
muscle is under VOLUNTARY CONTROLCardiac Muscle TissueComposed of
cells that are highly branched and uninucleate BOTH SKELETAL AND
CARDIAC MUSCLE TISSUE APPEAR STRIATEDFunction of the branching
cardiac cells appear dark under the light microscope these
junctions are called intercalated discsIntercalated discs house 2
types of membrane junctions:Gap JunctionsDesmosomesLocation:
organizes into cardiac muscle, the organ located only in the middle
layer of the heart wall = the myocardiumFunction: cardiac muscle
contracts under involuntary control to eject blood from the
chambers in the heartCells form gap junctions so they hold
together, uninucleateInvoluntary controlSmooth Muscle: Composed of
spindle shaped cellsUninucleate cellsOrganizes to form the organ
called smooth muscle2 types of smooth muscle organsSingle
Unit:Function: cells located in the walls of hollow structures in
the bodys tract contract under involuntary control to push
substances down the tractsMulti-Unit:Function: contract under
involuntary control to regulate the width or to regulate other
structuresEx: Arrector Pilli Muscle in the DermisIn cold
temperatures, the arrector Pilli muscles contract to decrease
surface area available on the skin for heat lossConserve heat in
the bodyCentral nuclei, no striations, arranged closely to form
sheetsMembranes as Simple OrgansOrgans have at least 2 types of
tissues in itSimplest type of organs in the human body is the
membranesMembranes are sheet like structures composed of at least 2
types of tissuesCutaneous Membrane = SkinOverlying tissue:
keratinized stratified squamous epithelial tissueUnderlying tissue:
Alveolar CT (Papillary Layer) and then Dense Irregular CT
(Reticular Layer)Mucus Membrane: lines structures in the tract of
the bodyOverlying Tissue:At entrance and end of tract:
non-keratinized stratified squamous epithelial Simple Columnar
Epithelial for inner tractUnderlying Tissue: Areolar CT referred to
as the lamina propriaSereous MembraneOverlying Tissue: simple
squamous epithelia = MEsotheliumUnderlying Tissue: Areolar CTAlways
epithelia supported by CT b/c epithelia needs nutrients from
CTSynovial Membrane made up of 2 types of tissues but of the same
primary class
Integumentary System-2 divisions (skin and accessory skin
structures)Skin is the largest organ of the body surface area 1.2
to 2.2. square metersWeighs 9 to 11 pounds = 7% of the total body
weightComposed of superficial epidermis and deeper dermisVaried
thickness: 1.4 mm-4.0 mmEpidermisBased on thickness= 2 types of
skinThin skin= epidermis is composed of 4 strata4 strata from
deep-superficialstratum basalestratum spinosumstratum
granulosumstratum corneumThick skin= epidermis is composed of 5
strataPalms, internal surface of fingers, soles of the feet5 strata
from deep-superficialbasalespinosumgranulosumlucidumcorneumall 4
layers are wider than in thin skinadditional layer of the stratum
lucidum above the stratum granulosum and below the stratum corneum
Stratum Basale deepest stratum of the epidermis abutting the
basement membrane above the dermis Single layer of cuboidal cells
called KERATINOCYTES (mitotically active always undergoing mitosis
to produce cells that occupy more superficial strata)Because the
keratinocytes are constantly undergoing mitosis, the stratum basale
is also known as the STRATUM GERMINATIVUMMelanocytes produce
melanin that is enclosed in melanosomes (arrange on the
top/superficial sides of the keratinocytes in the stratum
basale)Melanin acts as a chemical shield protecting the mitotically
active keratinocytes from mutations that can occur by the UV
radiation in sunlightMerkel cellscouple with the nerve endings in
the papillary layer of the dermis to form MERKEL DISCSMerkel discs
act as touch receptors for light touchMerkel cells do not act as a
touch receptor only MERKEL DISCSStratum Spinosum superficial to the
stratum basale (immediately above the stratum basale)Composed of
several layers of cells cells joined by desmosomes Cells contain
intermediate filaments called TONOFILAMENTSDESMOSOMES and
TONOFILAMENTS allow the stratum spinosum to withstand pulling
forces without the cells separatingCells appear spinyEpidermal
dendritic cells Langerhans cells act as macrophages to engulf and
digest pathogens and to activate the specific immune response if
the pathogen gains access to the bodyHence, intact epidermis is our
first line of defense against pathogens Stratum Granulosum above
the stratum spinosum3-5 layers of flattened cells filled with
granules2 types of granuleskeratohyaline granules: conatin tough
insoluble proteins called KERATIN that make the epidermis tough and
abrasive-resistantlamellated granules: contain glycolipids that
make epidermis water-proofStratum Lucidum only present in thick
skin; above the stratum granulosum3-5 layers of DEAD cellslayer of
the stratum appear translucent under the light microscope Stratum
Corneum20-30 layers of dead, flattened squamous-like cells, hence
the epidermis consists of 4-5 layers of cells is a stratified
squamous epitheliumdead cells in the stratum corneum filled
completely with keratincells are keratinized and the epidermis
becomes the keratinized stratified squamous epithelial dead cells
are coated with glycolipids epidermis is water-proof Dermis
consists of papillary and reticular layerPapillary layer
(superficial)Immediately below the reticular layer of the basement
membraneComposed of highly vascularized areolar CTSurface of the
papillary layer is thrown into involutions called DERMAL PAPILLAE
House 3 structures1. Blood capillaries2. Free nerve endings: act as
pain receptors3. Meissners Corpuscles act as touch receptors for
light touch (= merkel discs)In thick skin the surface of the
papillae are supported by mounds called dermal ridges which form
impressions on epidermal surface called EPIDERMAL RIDGES=friction
ridges increase friction and enhance grippingPattern of epidermal
ridges are unique and basis for finger printingReticular layer
(deep)80% of dermisComposed of dense irregular CTContains touch
receptors for deep pressure called PACINIAN CORPUSCLESLocation of
the Nervous Structures in the SkinMerkel Discs: epidermal-dermal
junctions; act as light touch receptorsMeissners Corpuscles:
papillary layer; light touch receptorsPacinian Corpuscles:
reticular layer; deep pressure touch receptorsAccessory Structures
of SkinSweat Glands (suderiferous glands)Multicellular exocrine
glands2 typesEccrine Sweat Glands3 million per personabundant in
palms, soles and foreheadSecrete sweat via merocrine mode of
secretion also known as merocrine glands99% waterhypotonic filtrate
of blood containing DERMICIDIN prevents the growth of
microorganisms on the surface of the skin sweat contributes to the
protective function of the skinlow pH between 4-6= slightly
acidic/acidicprevents growth of microorganisms on the surface of
the skinAntibodiesVitamin CSalts-NaClMetabolic wastesACIDIC MANTLE:
acidic pH of sweat prevents microbial growth on the surface of the
skinIntact epidermis acts as a physical barrier to the
microorganismsLow pH, dermicidin, antibodies guard against growth
of the microorganisms; chemical barriersEvaporation of sweat from
surface of the skin depends on body heat Body heat dissipated to
cause the evaporation drop in the core body temperature explains
why we sweat when we feel hotApocrine Sweat Glands2000 of them in
anogenital and axillary areasActivated after puberty when they are
stimulated by the sex steroid hormonesSecrete a viscous, yellowish
fluid onto hair follicles via merocrine mode of secretionSecretion
is associated with body odor also known as ODERIFEROUS glands2
special sweat glandsceruminous glandslocated in lining of external
ear canalsecrete bitter substance: CERUMEN (ear wax) that prevents
entry of foreign substancesmammary glandslocated in breastssecrete
milk to feed the young Sebacous Glands (Oil Glands)Simple alveolar
glandsFound all over body except palms/solesSecrete oily substance
called SEBUM into hair follicles and via pores to the surface of
the skinSebum softens and lubricates hair and skin because the oil
prevents water loss from the skin/hairsSebum also contains a
bactericidal agent that destroys bacteria on the surface of the
skin acts as a chemical barrier Secrete via HOLOCRINE mode of
secretionWhiteheads: sebum accumulated in glandsBlackheadsAcne:
inflammation of sebaceous glands from bacteriaHair=PiliShaft:
region exposed above the skinIn cross section, if the shaft appears
flat or ribbon-like the hair is curly; if oval wavy hair; if round
straight hair Root: region below the skin enclosed by the hair
follicle Hair follicle also contains the hair matrix cells in the
hair matrix undergo constant mitosis to produce new hair cells New
hair cells become heavily keratinized to form 3 concentric rings:
inner medulla, middle cortex, outer cuticleFunctionProtects against
traumaFiltration: vibrissae (nasal hairs) filter coarse particles
inside inhaled hair Base of hair follicle is wrapped by the root
hair plexus acts as touch receptors when the hair is bent Arrector
pili muscle: attached to the hair follicle (hair follicle and hair
reach the skin at an oblique angle)In cold weather, smooth muscle
in the arrector pili contract hair follicle and hair are pulled
from an oblique angle to a right angle position the hairs trap a
layer of cold air which acts as an insulator to prevent heat loss
from the body Nail scratching Skin cancer occurs in areas exposed
to the harmful affects of the UV radiationHas a strong genetic
disposition Basal cell carcinoma: proliferation of stratum basal
basale cells. The least malignant and most common type of skin
cancer (80%) grows slowlySquamous Cell Carcinoma: involves the
cells in the stratum spinosum. Second most common type of skin
cancer; grows rapidlyMelanoma: proliferation of the melanocytes;
most aggressive type of skin cancer, highly metastatic and
resistant to chemotherapy; least commonBurns Tissue damage by
intense heat, radiation, electricity and chemicals such as
acidsClassified based on severity: First-degree burns damage is
confined to only the epidermis; associated with redness, swelling
and pain; heal in 3day without medical intervention. Ex.
SunburnSecond-degree burns damage to the entire epidermis and the
papillary layer of the dermis; associated with blisters ( fluid
collection at the epidermal-dermal junction), swelling, redness and
pain; heal in 3-4 weeks if infection is preventedThird-degree burns
damage to the entire skin= damage to the entire epidermis and
dermis including all nerve endings hence, the burn site is not
painful; subjected to infections and fluid loss; medical
intervention involving grafting, fluid, protein and ion replacement
are required for healingWrinklesLoss of elasticity (thinning skin,
lack of moisture)Eat right, work out and drink waterEXAM 2 NOTES:
TISSUES AND SKIN10/24/13 6:47 PMBotox: blocks the transmission of
signals from nerves to the muscles, by hindering the production of
the neurotransmitter. When used for cosmetic purposes it causes the
muscle to relax giving it a smoother appearance
SKELETAL SYSTEMCartilage1. Hyaline2. Elastic3.
Fibrocartilage
Bones: each bone is an organ consists of bone tissue, connective
tissue coverings, blood vessels and nerves 4 classesLong: Longer
than they are wide Composed of diaphysis (shaft) and 2 epiphyses
(extended ends of long bone)Most are located in appendicular
skeleton Short: Roughly cuboidal in shapeLocated in the wrist=
carpals and ankle= tarsalSpecial types of short bones called the
sesamoid bones are embedded in tendons where they direct the pull
of the tendon when the skeletal muscle moves FlatFlattened bones
such as the sternumTend to have a protective function= protect
internal organs Cranial bones are flat bones protect the
brainIrregularNot classified as long, short or flatvertebrae2 types
of bone tissueCompact:Located on the exterior part of the
boneMatrix is solid Appears dense and are composed of structural
unites called OSTEONS Each consists of concentric rings of
structures called LAMELLAE , hence compact bone tissue is also
referred to as lamellar bone tissue In the core of the osteon is
the Haversian canal contains blood vessels and nervesAt the
junctions of adjacent lamallea lacunae= house osteoctyesOsteocytes
are kept viable by nutrients delivered from blood in the blood
vessels in the Haversian canal by smaller air-like canals called
CANALICULIOsteocytes are kept viable because they can revert to
osteoblasts to secrete new bone tissue for repair and growth of the
bone SpongyLocated inside the bone covered externally by compact
bone Structural units of spongy bone tissue needle-like structures
called TRABECULATEIrregularly arranged creating large spaces to
accommodate blood vessels and red bone marrow (also known as
myeloid tissue source of blood cells and platelets and contains
hemotopoietic stem cells) 2 regions of Long boneDiaphysisshaft of
the long bone composed of a collar of compact bone surrounding the
medullary cavityContains red bone marrow (children) and yellow bone
marrow (adults)Red bone marrow in the medullary cavity of long
bones produces blood cells and platelets in childrenYellow bone
marrow in the medullary cavity of long bones of adults does NOT
produce blood cells and platelets At the junctions of the diaphysis
with the epiphyses: Epiphyseal plate : present in the long bone of
childrenEpiphyseal lines: present in the long bone of adults 2
Epiphysescomposed of spongy bone tissue with red bone
marrowexternally each epiphyses is covered by a thin layer of
compact bone the ends of the epiphyses of long bones are capped by
the ARTICULAR CARTILAGE thin layer of hyaline cartilageMembrane=2
types of CT membranes (long bones)Periosteum- the outer CT membrane
that surrounds bonesDouble layered outer fibrous layer and the
inner osteogenic layerInner osteogenic layer contains osteoblasts
and osteoclastsOsteoblasts: bone-forming cells secrete bone tissue;
derived from mesenchymeOsteoclasts: bone resorbing cellsdestroy
bone tissueOuter Fibrous layer of the periosteum composed of the
highly vascularized dense irregular CTContains blood vessels,
nerves and lymphatic vessels these structures enter through the
nutrient foramina into canals right angles to the Haversian
canalsThese right angled canals are called perforating or Volkmanns
canals Nutrients are delivered from blood inside the blood vessels
in the fibrous layer and will go through the perforated canals to
the blood vessels in the Havasian canals (central canals) to
provide nutrients via canalicular to the osteocytes in the
lacunaeThe perforating canals extend into the spaces within the
spongy boneSpongy bone tissue stores red bone marrow in both
children and adultsRed Bone marrow = myeloid tissue a source of the
blood cells via a process known as hematopoiesisAttached to compact
bone by tough collagenous fibers called Sharpeys fibersEndosteum
single layer, contains osteoblasts and osteoclastsCovers the
canals, cavitites, and the trabeculae in a bone
General structure of Flat, short and irregular bones2 thin
plates of periosteal-covered compact bone with spongy bone with the
traberculae covered by the endosteum in between the 2 plates
OssificationPrenatal Ossification = Osteogenisis (development of
the bony skeleton form the embryonic skeleton)Intramembranous
OssificationBegins after the 8th week of in utero lifeMesenchyme
secrete fibrous connective tissue membrane under goes
intremambranous ossification to form membrane bones All membrane
bones have flat are flat bonesThe 8 cranial bones and the 2
claviclesAll membrane bones are flat bones but not all flat bones
are membrane bonesEndochondrial OssificationMesenchyme produces
chondroblastsChondroblasts secrete hyaline cartilage form the rest
of the embryonic skeleton not formed by fibrous connective tissue
membraneOssification of the hyaline cartilage to form the rest of
the bones in the bony skeletonAll bones in the bony skeleton except
the 8 cranial bones and the 2 claviclesEndochondrial ossification
results in long bones, flat bones, short bones, and irregular
bonesAfter endochondrial ossification in long bones, hyaline
cartilage still persists in 2 areas as the epiphyseal plates (at
the junctions of the diaphysis with the epiphysis) and at the
articular cartilage (caps the ends of the epiphysis)In short, flat
and irregular bones you have complete ossification of the hyaline
cartilage into bonePostnatal ossification-after birthLongitudinal
Ossification linear bone growth/ interstitial increases the length
of bones = heightIncrease in length of the long bones due to
activites in the epiphyseal plates at the junctions of the
diaphysis and the epiphyses of a long boneActive zones in the
epiphyseal plate looking at the proximal epiphyseal plates1.
Growth/ proliferation zoneChondroblasts secrete new hyaline
cartilage to add on to the epiphyseal face of the epiphyseal
plateGrowth zone is proliferation of chondroblasts = hyperplasia
which results in the increase in hyaline cartilage secreted onto
the epiphysial face of the epiphisial plate2. Hypertrophic ZoneThe
mature chondroblasts (chondrocytes) grow by hypertrophy (increase
in size)Large chondrocytes require more nutrients to remain
viable3. Calcification (deterioration) zone calcium phosphate
crytstals (hydroxyapatites) are deposited in the matrix of hyaline
cartilage calcification of the matrix = solid matrix which will
cause the chondrocytes to die4. Ossification (osteogenic) zone
osteoblasts move into the calcified matrix and secrete osteoid
organic matrix of bone tissuenew bone tissue is added on onto the
diaphyseal face of the ephiphyseal plate5. Resorption zone
osteoclasts reabsorb part of the newly added bone to increase the
height of the medullary cavity as the bone lengthens In children,
the amount (width) of the hyaline cartilage added on to the
epiphyseal face=EQUAL to the amount (width) of new bone tissue
added on to the diaphyseal face of the plate WIDTH (thickness) of
the plates remain the sameHowever, the proximal epiphyseal plates
have shifted superiorlyThe distal epiphyseal plates have shifted
inferiorlyResults in the lengthening of long bones
Hormonal Control of Postnatal Longitudinal Bone Growth (long
bones)Growth hormone: stimulates hepatocytes to produce
insulin-like growth factors (IGFs)Protein hormone that binds to
growth hormone receptors on hepatocytes (liver cells) to stimulate
the production of insulin-like growth factors (IGFs)IGFs bind to
IGF receptors on the chondroblasts to stimulate chondroblast
proliferation growth zone Hence, the growth promoting effect on
growth hormone is INDIRECT in longitudinal bone growthSex steroid
hormones (testosterone in the male and estrogens in the female)
synergize with growth hormone to cause growth spurtSynergize with
growth hormone to increase IGF production by the
hepatocytesIncrease IGF= increase chondroblast proliferation=
increase hyaline cartilage secreted on the epiphyseal face of the
epiphyseal plates Equal thickness of ossified tissue on the
diaphyseal faceHence, increase length of the diaphysis= increase
bone lengtheningAfter synergizing with growth hormone to stimulate
longitudinal bone growth, sex steroid hormones begin to antagonize
growth hormone from stimulating the hepatocytes to produce
IGFsDecrease in IGFs= decrease in chondroblast proliferation=
decrease in hyaline cartilage secreted onto the epiphyseal
faceHowever, the rate of ossification at the diaphyseal face
continues and it eventually outpaces the rate of hyaline cartilage
secretion the epiphyseal plates become ossified leaving a line
called the EPIPHYSEAL LINE present in the long bone of ADULTS The
ossification of the entire epiphyseal plates is termed epiphyseal
plate closureExample of endochondral ossification occurring after
birth (postnatal)Towards the end of adolescence. The sex steroid
hormones antagonize the actions of growth hormone and epiphyseal
plates become ossified EPIPHYSEAL PLATE CLOSUREheight
determined
Appositional Bone Growth2nd type of postnatal ossificationAll
bones widen and increase in diameter/thicknessBone formation on the
external surface of the bone outpaces the bone resorption in the
internal surface of the boneAll bones in the body undergo
appositional bone growth But only long bones undergo longitudinal
bone growth
Bone remodelingAdult bones constantly undergo bone formation on
the periosteal surface and bone resorption on the endosteal surface
bone remodelingFunctions of bone remodeling:Maintain calcium
homeostasisAllow for bone repair after fracturesIn healthy adults,
bone density remains constant becauseRate of bone formation= rate
of bone resorptionIf the rate of resorption outpaces the rate of
formation-= osteoporosis Control of bone remodelingHormonal
controlHow to maintain the normal calcium levels in bloodIn the
human body 1200 g of calcium1000 g stored in bones as the
hydroxyapatites200g left will maintain the blood calcium
levels9mg-11mg/100 cc of blood Blood calcium levels below 9 mg
hypocalcemiaNeed to correct it by getting calcium stored in bone
tissuePARATHYROID HORMONE (PTH) is released to stimulate
osteoclasts to cause bone resorption to release calcium from bones
into blood PTH stimulate bone resorption (bone breakdown) to
release the calcium phosphate salts in bloodStimulates the kidneys
to excrete phosphate leaving Ca2+ in blood. Also stimulates calcium
reabsorption from the kidneys- increase Ca2+ in bloodPTH stimulates
the synthesis of the most active form vitamin D called 1, 25
dihydroxyvitaminD Stimulates Ca2+ absorption from the small
intestine SUMMARY: based on the actions of PTH increase in blood
Ca2+ levels back into the normal rangeBlood calcium level above
11mg hypercalcemicYou need to store excess calcium in bone tissue
as the hydroxyapatites CALCITONIN is released to stimulate
osteoblasts to produce bone tissue and release stimulate
mineralizationuses calcium from bloodStimulates the osteoblasts to
secrete NEW bone tissueThe matrix of new bone tissue is mineralized
by hydroxyapitites (calcium phosphate crystals): calcium levels in
blood drop back into normal rangeMechanical force/ stresses Wolffs
LawBones remodel/grow in response to mechanical stresses placed on
the bonesBones that are stressed-pulled often by contracting
skeletal muscles undergo bone remodeling where bone formation
outpaces bone resoprtion resulting in thickening of these active
bones
JOINTS=ARTICULATIONSClassification: 2 waysFunctional: based on
amount of movement allowed at the joint3
typesSynarthroses-immovable jointsAmphiarthroses-slightly movable
jointsDiathroses- freely movable jointsStructural: based on the
material binding the body and the absence or the presence of a
joint cavity3 typesFibrous joints: bones joined together by dense
CT; joint cavity absent3 typessutures- present only in the skullIn
children: sutures are amphiarthrotic joints In adults: sutures are
synarthrotic jointsgomphoses- short periodontic ligaments that
connect the teeth into the alveolar sockets of the mandible and the
maxillaehence, gomphoses are referred to as PEG-IN-SOCKETS
jointssynarthrotic jointssyndesmoses- ligaments or bands connect
the bones fibrous materialligamentmembrane called interosseous
membranecomposed of ligaments synarthrotic jointscomposed of
interosseous membrane amphiarthrotic jointsinterosseous membrane
between the radius and the ulna allows for pronation of the forearm
Cartilaginous jointssynchondroses: joint formed by hyaline
cartilageThe epiphyseal plate connecting the epiphyses and the
diaphyses of a long bone are synchondrotic joints which are
synarthrotic joints symphyses: formed by fibrocartilageall
symphyses are amphiarthrotic joints intervertebral discs between
adjacent vertebrae pubic symphyses connect the os coxae (hip
bones)the pubic symphyses is an amphiarthrotic joint that moves
slightly to increase the pelvis inlet during labor Synovial joints:
class of joints with a joint cavity present; hence, all synovial
joints are DIARTHROTIC joints=movable Unique special features1. The
ends of the epiphyses of the long bones at the synovial joints are
capped by the ARTICULAR CARTILAGE covers the ends of all bones
forming synovial joints function: articular cartilage protects the
surfaces of the bones as the synovial joints move to minimize wear
and tear 2. Joint cavity: space that contains synovial fluid which
acts like a lubricant to reduce friction 3. ARTICULAR CAPSULE:
encloses the joint cavitydouble layered outer fibrous layer:
composed of dense irregular CTinner synovial membrane: composed of
areolar CT over dense irregular CTblood in the capillaries in the
fibrous capsule is filtered and secreted by cells in the synovial
membrane this filtrate is called the SYNOVIAL FLUID: located in the
joint cavity and inside the articular cartilagefunction: synovial
fluid acts as lubricant to reduce friction as the synovial joints
move; synovial fluid provides nutrients to the chondrocytes in the
articular cartilage; removes metabolic wastes from chondrocytes
back into the blood of capillaries; synovial fluid contains
phagocytes that engulf and digest cellular debris and any microbes
in the joint cavity 4. Ligaments composed of dense regular CT that
reinforce and stabilize synovial joints 3 types1. Intracapsular
ligaments: located deep to the articular capsuleex: cruciate
ligaments of the knee joint2. Capsular or intrinsic ligament: part
of the fibrous capsule of the articular capsule that blends into
the periosteum of the articulating bonesex: tibial collateral
ligaments3. Extracapsular ligaments: external to the articular
capsuleex: popliteal ligaments Additional structures that may be
present at certain synovial joints to add protection1. Menisci
certain types of synovial joints to improve the fit of the bones
forming the synovial joint minimize wear and tear of the
articulating surfaces ex: knee joint2. Bursae= bags of synovial
fluid that act as ball-bearings to decrease friction at sites of
active synovial joints ex: shoulder joint, knee joint 3. Tendon
sheaths elongated bursae wrapped around tendons subjected to
friction; decrease friction; found around tendons rubbing against
muscle, ligaments and bones 6 types of Synovial joints: based on
the structure of the articulating surfaces of the bones forming the
synovial joints the structure and shape articulating surfaces
dictates the types of movements allowedTypes of movements:1.
Gliding movements gliding or slipping of the articulating
surfaces2. Flexion movement which results in the decrease of the
angle of a synovial joint the articulating surfaces get closer to
each other 3. Extension movement that increases the angle of the
synovial joint articulating surfaces separate pull away from each
otherbring a flexed knee to the anatomical position is an extension
4. Abduction movement of limbs away from the midline of the body 5.
Adduction movement of limbs towards the midline of the body 6.
Circumduction abduct the limbs and move the digits to describe a
cone in space7. Rotation movement around an axis 6 types1. Plane
joint : articulating surfaces are flat Movement allowed: gliding or
slipping intercarpals and intertarsals2. Hinge joint: one articular
surface of one bone is cylindrical and the articular surface of the
second bone is a trough; Hinge joints allow for flexion and
extensionElbow joint 3. Pivot joint: the articulating surface of
one bone is round and the articulating surface of the second bone
is a sleeve or ring .Movement allowed: Rotationatlantoaxial joint
allows for movement of the head to motion NO4. Condyloid
(Ellipsoid) joint: the articulating surface of one bone is an oval
protrusion and the articulating of the second bone is an oval
depression. Movements allowed: flexion, extension, abduction,
circumduction, adduction atlanto-occipital joint allows us to
motion YES5. Saddle joint: the articulating surface of one bone has
convex and concave surfaces articulating surface of the second has
both concave and convex surfaces Only one location in the human
body carpometacarpal joint of the thumb 6. Ball-and-socket joint:
the articulating surface of one bone is spherical and the
articulating surface of the second bone is s a cuplike socketThe
ultimate diathrotic joint freely moveableEXAM 2: BONES AND
JOINTS10/24/13 6:47 PMcoxal joints and glenohumeral joints
The Muscular System3 types of muscle tissue that organize with
CT, blood vessels, lymphatic vessels and nerves to form the 3 types
of organs (skeletal, cardiac, and smooth MUSCLE)Skeletal Muscle
Tissuestriations, long cylindrical cells called muscle fibers;
multinucleateattachment can be direct or indirectCardiac Muscle
TissueStriations; branching cells with intercalated discs;
uninucleateSmooth Muscle TissueNo striations; spindle-shaped cells;
uninucleateSKELETAL MUSCLE (organ)Skeletal muscle tissue is
composed of the skeletal muscle FIBERSEach skeletal muscle fiber is
surrounded by the EDNOMYSIUMA bundle of endomysium covered skeletal
muscle fibers FASICLEEach fascicle is surrounded by the PERIMYSIUMA
bundle of perimysium covered fascicles SKELETAL MUSCLE Skeletal
muscle is wrapped in EPIMYSIUMSkeletal muscle, the organ, attaches
to skeletal structuresBone and cartilage, hence the name skeletal
muscleAttach in 2 ways: direct attachment and indirect
attachmentDirect attachment of skeletal muscles: muscles attach
directly to the surface of bones these bones tend to be flat bones
such as the cranial bonesIndirect attachment: the epimysium blends
into a tendon the tendon attaches the skeletal muscle to the
skeletal structures (bone or cartilage)ADVANTAGES:1. Space saver
attachment via tendons occupies less space on the surface of the
skeletal structures2. Indirect attachment makes it possible for
skeletal structures to be moved when the skeletal muscle contracts2
attachment sites: the ORIGIN and INSERTIONThe bone that moves (the
movable bone) when the skeletal muscle contracts is known as the
INSERTION; and the bone that does not move ( the immovable bone) is
the ORIGIN. Hence, when the skeletal muscle contracts, the
insertion moves toward the origin.Each skeletal muscle fiber80% of
its volume will be occupied by the myofibrils (rod-like)run the
entire length of the skeletal muscle fibers skeletal muscle fibers
run the entire length of the skeletal muscle organeach myofibril
contains 2 types of myofilaments1. Thick filamentscomposed of
protein MYOSINconsists of a tail and 2 globular heads 16 nm300
myosin form a dark band called A bandMyosin globular heads have
binding sites for actin. Binding sites for ATP and contains the
enzyme ATPase2. Thin filaments composed of protein ACTINanchored by
the Z discs (lines)the distance between 2 successive Z
discsSARCOMERESarcomere run the entire length of the myofibril and
myofibrils run the entire length of the skeletal muscle fibers,
which run the entire length of the skeletal muscle organ Sarcomeres
are the smallest contractile units in the skeletal muscle, hence
sarcomeres are referred to as the structural unit of skeletal
muscleThe alternating arrangement/ pattern of the thick and thin
filaments gives skeletal muscle a STRIATING appearance Contain 3
different proteinsActin: contains the binding sites for myosin
globular heads; forms the structural framework of the thin filament
Tropomyosin: rod-shaped regulatory protein that spirals around the
actin and blocks myosin binding sites on actin in a relaxed
skeletal muscle, hence actin sites are NOT accessible by the actin
binding sites on the myosin headsTroponin- 3 polypeptide complex
namelyTnC- binds calcium ionsTnT- binds to tropomyosinTnI-
inhibitory subunit that binds to actinMyoglobin (same function of
hemoglobin) unique RED pigment in skeletal muscle
fibersBinds/releases oxygen (O2)Inclusions in the cytoplasm of
skeletal muscle fibersCytoplasm of skeletal muscle fibers
SARCOPLASMGlycosomes contain glycogen: storage form of glucose in
animal cellsMitochondria aerobic respiration is used by skeletal
muscle fibers to produce energy (ATP) required to sustain skeletal
muscle contractionAerobic catabolism of 1 g of glucose yields 38
ATPAnaerobic catabolism of 1 molecule of glucose yields 2
ATPSarcoplasmic Reticulum (SR) specialized smooth ERSR
stores/releases Ca2+ into the sarcoplasm to cause skeletal muscle
contraction Expanded ends of the SR are called TERMINAL
CISTERNAESarcolemma-plasma membrane of the skeletal muscle
fiberTransverse tubules (T-tubules)- invaginations (infoldings) of
the sarcolemma into the sarcoplasm called 3 structures in a
skeletal muscle fiber= TRIAD1. Terminal Cisterna2. T-tubule3.
Terminal Cisterna Sarcomeres: structural units of skeletal muscle=
each skeletal muscle is composed of repeated units arranged end to
end called sarcomeresComponents:A band= thick filamentsM line= line
that bisects and anchors the A bandsThin filaments: alternating
with A bands; this alternating pattern of thick and thin filaments
results in STRIATED appearanceZ lines (z discs)= anchor the thin
filamentsH zone= middle region of the A band not overlapping with
the thin filamentsI bands= regions of the thin filaments not
overlapping with the A bandSliding Filament Mechanism of Muscle
ContractionExplains how sarcomeres shorten which leads to the
shortening of skeletal muscle termed CONTRACTIONStates that the
shortening of a skeletal muscle occurs when the thin filaments in
the sarcomeres slide inward into the H zone (toward the M line)
pulling the Z discs inward hence, sliding of the thin filaments
results in shortening of the sarcomeresSarcomeres (distance between
2 successive Z discs) is shortenedSarcomeres shorten myofibrils
shorten skeletal muscle fibers shorten skeletal muscles
shortenAccording to the sliding filament mechanismWhen the thin
filament slides into the H zone, then there is complete overlap
between the thin filaments and the A band (Z discs are abutting the
A bands) the H zone disappears and the I bands disappearWhat causes
the thin filaments to slide into the H zone, resulting in the
shortening of sarcomeres?Excitation- Contraction CouplingEach
skeletal muscle (the organ) is innervated by a motor neuron via
axons (conducts impulses from the central nervous system to
skeletal muscles)As the motor neuron approaches the skeletal
muscle, its end branches called AXON TERMINALS enter into the
skeletal muscle and make contact with skeletal muscle fibers1-1
ratioEach axon terminal makes contact with 1 skeletal muscle fiber;
each skeletal muscle fiber can make contact with only one axon
terminalThe motor neuron and all the skeletal muscle fibers it
makes contact via its axon terminals MOTOR UNIT (come in different
sizes)Small motor unit 10 skeletal muscle fibers
contractedAcrtivated first Medium sized 50-100Larger sized 1000
Generate the most force; activated lastExplains how action
potential developed/transmitted by the axon of the motor neuron is
coupled to the shortening of the sarcomeres sliding of the thin
filaments into the H zoneThe junction of the axon terminal with the
motor end plate separated by a thin gap is called the neuromuscular
junction (N-M junction)N-M junction involves the motor end plate
highly folded region of the sarcolemmaIncrease surface area hence,
the motor end plate has the highest number of the acetylcholine
receptorsAcetylcholine. Is the neurotransmitter released into the
neuromuscular cleft (gap between the axon terminal and the motor
end plate)Acetylcholine diffuses from the cleft to bind to its
receptors on the surface of the motor end plate When acetylcholine
binds to its receptors, the motor end plate depolarizes (reversal
of the resting membrane potential)Interior of sarcolemma becomes
slightly less negative. Depolarization of the muscle end plate
develops into action potential which spread across the entire
sarcolemma, including the t-tubules (invaginations of the
sarcolemma)When the action potential enters the t-tubule of the
TRIAD, the terminal cisternae depolarize and Ca2+ is released from
the sarcoplasmic reticular into the sarcoplasm Increase in
intracellular Ca2+ levels in the skeletal muscle fiber increase in
Ca2+ in the sarcoplasm of the skeletal muscle fiberCa2+ in the
sarcoplasm binds to the TnC (subunit of =troponin) leads to a
conformational change in the troponin which affects TnT bound to
tropomyosin- results in the tropomyosin being moved from blocking
the myosin-binding sitesThe sites on actin are accessible to the
myosin globular headsOnly activated myosin globular heads can bind
to sites on actin Activated myosin globular headsWhen the ATPase
splits the ATP into ADP and Pi, these 2 are still attached to the
myosin globular headsactivated myosin globular headThe activated
myosin globular head binds to its accessible site on actin at a
right angleThe attached myosin globular head to its site on actin
CROSS BRIDGEthe ADP and Pi dissociate from the cross bridge results
in the change of orientation of the cross bridge termed the POWER
STROKEthe attached cross bridge changes its orientation form a
right angle to an oblique angle results in the thin filaments being
pulled alongThe power stroke causes the thin filament to be moved
inward in the sarcomere toward the M line termed SLIDING OF THE
THIN FILAMENTS INTO THE H ZONE shortening of the sarcomere
shortening of the skeletal muscle How a contracted skeletal muscle
relaxes1. Turn off the activation of the motor neuronAction
potential are NOT being producedAcetylcholine is NOT being released
into the neuromuscular cleft2. Destroy any acetylcholine in the
neuromuscular cleft using the enzyme
acetylcholinesterase3.Sequester (take back) the Ca2+ from the
sarcoplasm into the SR4. New ATP binds to the ATP site in the cross
bridge to cause cross bridge detachment from actin LACK OF ATP
(complete absence of ATP) result in a contraction of the body
termed RIGOR MORTISObserved in dead individual Dying cells unable
to exclude calcium, calcium influx into muscle cells promotes
formation of myosin cross bridgesCross bridge detachment is
impossible (ATP synthesis stops after breathing stops)Deficit
(shortage) of ATP is in living individual MUSCLE FATIGUE Sources of
ATP to support skeletal muscle contractionStored ATP-used
firstCreatine Phosphate (CP)- ATP produced from direct
phosporylation of ADP by CP using the enzyme Creatine
Phosphatease:CP + ADP ATP + creatineAerobic catabolism of glucose-
produces most ATPAnaerobic catabolism of glucose- pyruvic acid is
converted into LACTIC ACID which reduces blood pH and contributes
to muscle fatigueHow is ATP generated used in skeletal muscle
contraction1. ATP is hydrolyzed by ATPase to produce ADP and Pi to
activate the myosin heads2. ATP is required for cross bridge
detachment3. ATP is required for the sequestration of calcium ions
back into the SR for storage (active transport)Factors that affect
the strength/ force of skeletal muscle contraction Size of motor
units activated larger motor units generate more force than smaller
motor unitsNumber of motor units activated force increases as the
number of motor units activated increasesRecruitment = smaller
motor units are activated first followed by larger motor
unitsFrequency of skeletal muscle activation force increases as the
rate of stimulation by motor neurons increasesThe length of the
sarcomeres prior to contraction sarcomeres at the optimum length
(2.2-2.6) maximum force generated by the skeletal muscleslight
overlap between the A band and the thin filaments with H zone
stretched sarcomeres prior to contraction there is no overlap
between the A band and thin filaments hence, the activated myosin
globular heads cannot bind to their sites on actin NO SLIDING OF
THIN FILAMENTSwide H zone zero tension/ force generatedif the
sarcomere length is shortened prior to contraction complete overlap
between the A bands and thin filaments but there is NO H zone cross
bridge can form, but the thin filaments cannot slideNO H zone to
slide intoZero force generated2 main categories of skeletal muscle
contractionisometric contractionforce(tension) generated by the
muscle is increasing at a constant muscle length ( isometric = same
length); occurs when the weight exceeds the force generated by the
muscle isotonic contraction muscle shortens at a relatively
constant force ( isotonic = same force); force generated by
skeletal muscle exceeds the weight so the skeletal muscle contracts
and work is done, such as lifting the weight.3 Skeletal Muscle
Fiber Typesbased on Speed of Contraction: 2 typesslow and fast
fibers due to the speed at which myosin ATPase hydrolyzes ATPbased
on Major Pathway for ATP Production: 2 waysaerobic respiration:
oxidative fibers typesanaerobic respiration using more glycogen:
glycolytic fiber types1. Slow Oxidative Fibershave the highest
content of myoglobin binds and releases oxygenrequired for aerobic
catabolism of glucose to yield ATPmyoglobin RED PIGMENTalso known
as RED FIBERSpredominant in skeletal muscles involved in
endurance-type of activities postural muscles suited for
endurance-type events such as running a marathon successfully 2.
Fast Oxidative Fibers
3. Fast Glycolytic fibers lowest myoglobin hence, they appear
whitish and referred to as the WHITE FIBERSactivities that are
short-lived but intense a lot in chest muscles and muscles of the
backPectoralis major/minor, deltoid, latissmus dorsi
A skeletal muscle fiber can only undergo hypertrophyHence,
muscle grows by hypertrophy and NOT by hyperplasia (cell
number)Effect of Exercise on Skeletal MusclesAerobic or endurance
exercise (jogging, biking, swimming) changes in skeletal
muscle:Increase in capillariesIncrease in mitochondriaIncrease in
myoglobin contentOverall, endurance improved= increase in
staminaResistance exercise (weight lifting, isometric exercises
where muscle are pitted against immovable objects) changes I
skeletal muscle:Increase in the size of skeletal muscles=
hypertrophy of skeletal muscles occur due to increase in the number
of myofibril within each muscle fiberIncrease in glycogen
contentOverall, bulky muscles generate more force=increase in
muscle strength Smooth Muscle: the organNot striatedSarcomeres are
absentThick filaments and thin filaments are present but not
arranged in alternating pattern. Rather they are arranged
diagonally Z discs are absent (dense bodies)Transverse tubuals are
absent- therefore triads are absent.There are shallow concavities
of the sarcolemma of the smooth muscle called caveolaeCaveolae
contain extra cellular fluid rich in calciumDense bodies are
present in smooth muscle cellsDense bodies- anchor the thin
filamentsSR is present but poorly developed. Terminal cisternae are
absentPresent is the calcium modulating protein called.
CalmodulinCamodulin binds Ca++ThroponinC and the entire troponin
absent in the thin filaments of the smooth muscle cells. Hence the
thin filaments consist of 2 proteins- actin and tropomyosinTroponin
does not block myosin binding sites on actin when smooth muscle is
relaxed.Intermediate filaments are present in smooth muscle cells.
Hence smooth muscle can withstand stresses placed on it.
Differences between the E-C coupling in the skeletal muscle and the
smooth muscle1)Skeletal muscle can only be stimulated to contract
by activation of the motor neuron. Innervated the skeletal muscle.
Skeletal muscle relaxation occurs when the motor neuron is not
being activated. In smooth muscle can be activated to contract by2)
a pacemaker activity intrinsic to the smooth muscle- pacemaker
activity stimulates smooth muscle contraction, external
innervationsIf present, regulates the intrinsic pace set by the
pacemaker activityb) Chemicals such as hormones stimulates smooth
muscle contraction . Unlike skeletal muscle, chemicals can cause
smooth muscle relaxation Ex. Epinephrine- stimulates the
contraction of smooth muscle in the wall of blood vessels-leading
to basel constriction- the hormone atrial natricetic- causes
contracted smooth muscle to relax leading to vasodilatation.3)
Smooth muscle is innervated by autonomic nerve fibers and forms the
DIFFUSE junctions with smooth muscle cells. Diffuse junctions are
irregular with wide clefts that form between the bulbous end of the
autonomic nerve fiber called a varicosity and a smooth muscle
cellUnlike skeletal muscle- a smooth muscle cell can form diffuse
junctions with several varicosities. No longer a 1: 1 ratio.When
the autonomic nervous system is activated- the autonomic nerve
fibers innervating the smooth muscle- you may cause smooth muscle
contraction of relaxation aka Autonomic nervous system
SympatheticParasympatheticIf the sympathetic nervous system of the
autonomic nervous system is activated, the smooth muscle in the
walls of the bronchial (tube like structures leading into the
lungs)- the activation will cause smooth muscle relaxation . IF the
Para sympathetic nervous system is activated- contraction will be
the cause of the smooth muscle of the walls of the
bronchialDifferences between skeletal muscle contraction (sliding
o