Cells & Tissues. Introduction to Cells and Tissues Slide 3.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carry out all.

Cells & Tissues

Introduction to Cells and TissuesIntroduction to Cells and Tissues

Slide 3.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Carry out all chemical activities needed to sustain life

Cells are the building blocks of all living things

Tissues are groups of cells that are similar in structure and function

Disorders can happen due to a problem with a cell organelle and its function

Anatomy of the CellAnatomy of the Cell


Cells are not all the same

All cells share general structures

Cells are organized into three main regions Nucleus

Cytoplasm

Plasma membrane

Figure 3.1a

Cell DiversityCell Diversity

Slide 3.19aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 1, 2


Slide 3.19bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 3


Slide 3.19cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 4, 5


Slide 3.19dCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 6, 7

Plasma Membrane – Begin notesPlasma Membrane – Begin notes


Maintains the boundaries of the cell - Barrier for cell contents

Phospholipid bilayer interspersed with proteins Impermeable to water soluble substances

Permeable to lipid soluble substances

Plasma MembraneHydrophilic vs. HydrophobicPolar head and non polar tails make phospholipids self orienting in body fluids

Very important for membrane construction and repair to happen correctly

Plasma MembraneCholesterol

Stabilizes bilayer by immobilizing phospholipids

Plasma MembraneEnzymes that act as catalysts for reactionsPeripheral proteins

Stuck on membrane surface or on other proteins and act as binding sites for hormones or chemical messengers (these act as enzymes mentioned earlier)ADD: Can also have mechanical functions

Changing cell shapeMuscle contraction

Integral ProteinsProteins that extend through the width of the membrane (transmembrane)Known as INTEGRAL proteins have transport functions

Can cluster to form pores/channels through which water, small water soluble molecules & ions can passAct as carriers that bind to a molecule & help it move through

GlycoproteinsGlycoproteins (sugar-proteins)

Branching sugar groups attached to a proteinExamples:

Determine blood typeAct in cell recognition (MHC)Receptors for toxins, viruses, bacteria

GlycocalyxCoating of cell surface by glycoproteins and sugar groups – gives fuzzy look

Plasma MembranePlasma Membrane


Figure 3.2

Membrane Specializations

Plasma Membrane SpecializationsPlasma Membrane Specializations


Microvilli Finger-like projections

that increase surface area for absorption

Imp: nutrient absorption/waste exchange

Found on surface of absorptive cells such as small intestine & kidney tubules

Figure 3.3



Tight Junctions

Form impermeable junctions to prevent passage of molecules

Imp: prevent free passage of molecules

Example: lining of digestive tract

Imp: digestive enzymes & bacteria kept away from cells

Figure 3.3



Desmosomes

Form mechanical junction or adhesion layers to prevent separation of tissues due to mechanical stress

Examples: skin, heart muscle, neck of uterus

Figure 3.3



Gap junctions

Provide for direct passage of chemical substances between adjacent cells

Figure 3.3



Gap junctions

Cells are connected by Connexons: hollow cylinders (transmembrane)

Important

Allowing direct passage of molecules,etc.

Figure 3.3



Gap junctions

Found in electrically excitable tissues (heart, smooth muscle, embryonic)

Importance: allowing smooth synchronization due to ion passage

Figure 3.3

FluidsFluids


Cytosol

Fluid portion that suspends stuff inside cell

Part of cytoplasm

Interstitial fluid

AKA: EC (extracellular matrix)

Fluid that surrounds a cell

Cytoplasmic OrganellesCytoplasmic Organelles


Figure 3.4

Cytoplasmic OrganellesCytoplasmic Organelles


Figure 3.5

Cell Transports

INTRODUCTIONINTRODUCTION


Membrane Transport – movement of substance into and out of the cell

Transport is by two basic methods Passive transport

No energy is required

Active transport

The cell must provide metabolic energy

Passive TransportMovement of substances across the cell membrane WITHOUT using energy

No ATP required by the cellMoves from HIGH to LOW concentrationsCONCENTRATION GRADIENT is the difference between the high and low concentration

Passive TransportOnly a limited number of substances can go through the membrane

Which?N2, O2, water, carbon dioxide, glucose, fat soluble substances

Passive Transport ProcessesPassive Transport Processes


Diffusion – No ATP required

Figure 3.8

INTRODUCTION TO DIFFUSIONINTRODUCTION TO DIFFUSION


Simple diffusionMovement is from high concentration to low concentration, (down a concentration gradient)

Solutes are lipid-soluble materials or small enough to pass through membrane pores (such as water)

BBC Education - AS Guru - Biology - Cells - Pathways - Simple Diffusion (Passive)

Diffusion through membrane

Example of DiffusionOxygen must diffuse from the higher pressure in your lungs to the lower pressure in your blood so it can then get to your cellsCarbon dioxide must diffuse from the higher pressure in your blood to the lower pressure in your lungs so you can then exhale it

Passive Transport ProcessesPassive Transport Processes


Osmosis – simple diffusion of water

Highly polar water (a small molecule) easily crosses the plasma membrane

Osmotic Pressure

Tendency of a solution to move water into and out of itself or The force exerted by the water motion against the membrane

TonicityTonicity compares the concentrations of the water molecules on the inside and outside of the cellThe terms can also be used to describe the concentrations of what is dissolved in the waterIMPORTANT INFO: Just remember: All Substances ALWAYSmove from high to low concentration in passive processes (No ATP)

ISOTONICConcentration of water molecules is EQUAL on both sides of membranePressure on membrane is equal from both sides so no net water motion

HYPERTONIC( have a higher solute and lower water concentration than the cells do) in other words, water concentration will be more concentrated inside of the cell than outside the cell SO:Pressure on the inside of the membrane causes water to move OUT of the cellProblem: the cell will CRENATE aka. shrivel up

CrenationCrenate: bloodcells are shrivelingbecause wateris leaving

They are dehydrating

HYPOTONIC( have a lower solute and higher water concentration than the cells do) in other words, water concentration will be less concentrated inside of the cell than outside the cell SO:Pressure on the outside of the membrane causes water to move INTO the cellProblem: the cell will LYSE aka. rupture

HYPOTONICConcentration of water molecules is greater on the outside of the cellPressure on the outside of the membrane causes water to enter the cellProblem:

Swell & lyse: animal cell may rupture

HypotonicNotice RBC isvery plumpNo dent incenter

osmosis#Osmosis#Osmosis#Osmosis

Facilitated DiffusionSome molecules need a little help to get through the membrane so they use a CARRIER PROTEINThe cell still does NOT need to use energy (ATP)BBC Education - AS Guru - Biology - Cells - Pathways - Facilitated Diffusion

Carrier ProteinsVery molecule specific

Structure determines function so the types of carrier proteins on a cell gives the cell job specificity

Speed up diffusionAffected by ion charges, concentration gradients, chemical substances in your blood (such as alcohol, medications, etc)

Carrier ProteinsHelp in glucose absorption

FYI (don’t memorize): In type II diabetes – the carrier proteins don’t listen to your insulin so your cells don’t let the glucose in – thus your blood sugar levels goes up which causes LOTS of problemsInjecting insulin into your body won’t help because your cells won’t listen to itPrevent type II diabetes by restricting the amount of sugary foods you eat

Diffusion through the Plasma Diffusion through the Plasma MembraneMembrane


Figure 3.9

Plasma Membrane proteins

RecognitionReceptorsEnzymesTransport Channels

FEATURES OF ACTIVE TRANSPORT

Energy required to move substances AGAINST the concentration gradient

BBC Education - AS Guru - Biology - Cells - Pathways - Active TransportIn other words, from a low into a high concentrationOR some other reason that a molecule might not be able to cross the membrane on its own power

Needed in order to maintain homeostasis in certain conditions

FEATURES OF ACTIVE TRANSPORT

Maintaining homeostasis examples:Nutrients that are scarce in the cell’s environment

Cell needs to take in ALL the nutrients (not leaving half outside which is what happens at equilibrium!)

Kidney cells sorting waste material from needed material

Don’t want half the waste left in your blood!

MOLECULAR (ION) PUMPThis is also known as solute pumping & there are several types. We will focus on the general infoCarrier protein binds to the particleAnother location on the carrier protein binds to an ATP for energyEnergy in ATP is transferred to protein so it can move particle in desired direction

Ion pumpSome pumps are coupled – move one ion in while moving another ion out

Active Transport ProcessesActive Transport Processes


Figure 3.10

EXOCYTOSISBulk transport of substances OUT of the cell

Examples:Producing proteins to secrete to surroundings:

Digestive enzymes in stomach, saliva, insulin, sweat

Excreting waste from cell to blood

Golgi apparatus aids in secretion & storage then exocytosis excretes them from cell to where ever they are neededhttp://www.bbc.co.uk/education/asguru/biology/01cellbiology/05pathways/09endoexo/index.shtml

Active Transport - exocytosisActive Transport - exocytosis


Figure 3.11

ENDOCYTOSISBulk transport of material INTO cellMaterial is engulfed to form a vacuole – it does not ever go through the membraneVacuole can then join with a lysosome so it can digest the food

ENDOCYTOSISPHAGOCYTOSIS

Engulfing of LARGE particlesEx: a white blood cell engulfing a bacteria or virus

PINOCYTOSISEngulfing of SMALL particles of food or liquid

Active Transport -endocytosisActive Transport -endocytosis


Figure 3.12

Types of Tissues

Body TissuesBody Tissues


Cells are specialized for particular functions

Tissues Groups of cells with similar structure and

function

Extracellular Matrix

Aka: intercellular matrix, interstitial fluid

“cell glue” between cells

Histology = study of tissue

Body TissuesBody Tissues


Four primary types (functional categories) Epithelium =

protection/secretion/absorption/filtration Connective tissue = support & structure Nervous tissue = communication & control Muscle = movement (internal & external

EPITHELIAL TISSUES

Epithelium CharacteristicsEpithelium Characteristics


High cellularity = cells fit closely together – very little EC matrix

Contains specialized contacts = tight junctions & desmosomes

Tissue layer always has one free surface (apical) that may have modification such as microvilli

Epithelium CharacteristicsEpithelium Characteristics


Avascular = no blood vessels within it – diffusion provides nutrients & carries waste away – lots of nerve fibers

Basement Membrane

Reinforcement & connection

Defines boundaries – cancer causes a breach in these boundaries

Regenerate easily if well nourished

Found in areas of high friction

Classification of EpitheliumClassification of Epithelium


Shape of cells

Squamous – flattened

Cuboidal – cube-shaped

Columnar – column-like

Figure 3.16b

Classification of EpitheliumClassification of Epithelium


Number of cell layers

Simple – one layer

Found in areas of transport

Stratified – more than one layer

High abrasion areas for protection

Secretory membranes

Named according to cell shape on apical surface Figure 3.16a

Covering & Lining Epithelium

Endothelium = friction reducing – lines all circulatory system organsReduces friction due to blood flow

Epithelial MembranesMucous membranes

Line body cavities OPEN to the exteriorExample: digestive, respiratory, urogenitalMucus protects by trapping microorganisms, substances in mucus will destroy them

Epithelial MembranesCutaneous Membranes

SkinHelps waterproof & protect body First line of defense in immune system

Epithelial MembranesSerous Membranes

Lines all CLOSED body cavitiesSerous fluid located between layers to reduce friction due to organ motion

Remember naming:Visceral vs. parietalPleura, pericardium, peritoneum

Glandular EpitheliumGlandular Epithelium


Gland – one or more cells that secretes a particular product

Two major gland types Endocrine gland

Ductless – secretes product directly into blood or tissue

Produces hormones

Exocrine gland

Empty through ducts to the epithelial surface

Include sweat and oil glands

Google Image Result for http://www.willamette.edu/~stas/physiology/labs/lab1/epithelial2a.jpg

Identification of Epithelial tissue

See handoutGo to website:

Essentials of Human Anatomy & Physiology

Make flashcards & studyStudy microscope slides in class

Simple EpitheliumSimple Epithelium


Simple squamous Single layer of flat

cells

Usually forms membranes

Lines body cavities

Lines lungs and capillaries

Figure 3.17a



Simple cuboidal Single layer of

cube-like cells

Common in glands and their ducts

Forms walls of kidney tubules

Covers the ovaries Figure 3.17b



Simple columnar

Single layer of tall cells

Often includes goblet cells, which produce mucus

Lines digestive tract

Figure 3.17c



Pseudostratified Single layer, but

some cells are shorter than others

Often looks like a double cell layer

Sometimes ciliated, such as in the respiratory tract

May function in absorption or secretion

Figure 3.17d

Stratified EpitheliumStratified Epithelium


Stratified squamous Cells at the free edge

are flattened

Found as a protective covering where friction is common

Locations Skin Mouth Esophagus Figure 3.17e



Stratified cuboidal Two layers of cuboidal cells

Stratified columnar Surface cells are columnar, cells

underneath vary in size and shape

Stratified cuboidal and columnar Rare in human body

Found mainly in ducts of large glands



Transitional epithelium

Shape of cells depends upon the amount of stretching

Lines organs of the urinary system

Figure 3.17f

Connective tissues

Support & strengthen & provide structure

Connective TissueConnective Tissue


Found everywhere in the body

Includes the most abundant and widely distributed tissues

Functions Binds body tissues together

Supports the body

Provides protection

Insulates to maintain body temperature

Transportation of other molecules

Origin of Connective Tissue

Mesenchyme: embryonic tissue that differentiates into all forms of CT

Connective Tissue CharacteristicsConnective Tissue Characteristics


Variations in blood supply

Some tissue types are well vascularized

Some have poor blood supply or are avascular

Blood supply is necessary for healing (it brings oxygen & “spare parts”)

Cartilage vs bone

Connective Tissue Characteristics

Composed largely of EC matrixImportant to remember: More matrix = less flexibility

Extracellular MatrixExtracellular Matrix


Two main elements Ground substance - proteins and

polysaccharide molecules that function as a molecular sieve to diffuse nutrients & other substances

Fibers – know function Produced by the cells Three types

Collagen fibers – tensile strength Elastic fibers – stretch with recoil Reticular fibers - supportive

CellsPrefixes

FibroOsteoChondroHemo(cyto)

SuffixesBlast – build the tissueCyte – maintain the tissueClast – breakdown the cells

Websitehttp://www.udel.edu/Biology/Wags/histopage/colorpage/cct/cctm.GIF

Connective Tissue TypesConnective Tissue Types


Bone (osseous tissue) Composed of:

Bone cells in lacunae (cavities)

Hard matrix of calcium salts

Large numbers of collagen fibers

Used to protect and support the body Figure 3.18a



Hyaline cartilage Most common

cartilage

Composed of:

Abundant collagen fibers

Rubbery matrix

Entire fetal skeleton is hyaline cartilage Figure 3.18b



Elastic cartilage

Provides elasticity

Example: supports the external ear



Fibrocartilage

Highly compressible

Example: forms cushion-like discs between vertebrae

Figure 3.18c



Dense connective tissue Main matrix element

is collagen fibers

Cells are fibroblasts

Examples Tendon – attach

muscle to bone

Ligaments – attach bone to bone Figure 3.18d



Areolar connective tissue Most widely

distributed connective tissue

Soft, pliable tissue

Contains all fiber types

Can soak up excess fluid Figure 3.18e



Adipose tissue Matrix is an areolar tissue in which fat

globules predominate

Many cells contain large lipid deposits

Functions Insulates the body

Protects some organs

Serves as a site of fuel storage

Figure 3.18f



Reticular connective tissue Delicate network of

interwoven fibers

Forms stroma (internal supporting network) of lymphoid organs Lymph nodes Spleen Bone marrow

Figure 3.18g



Blood

Blood cells surrounded by fluid matrix

Fibers are visible during clotting

Functions as the transport vehicle for materials

Figure 3.18h

Muscle TissueMuscle Tissue


Function is to produce movement

Three types Skeletal muscle

Cardiac muscle

Smooth muscle

Muscle Tissue TypesMuscle Tissue Types


Skeletal muscle Can be controlled

voluntarily

Cells attach to connective tissue

Cells are striated

Cells have more than one nucleus

Figure 3.19b



Cardiac muscle Found only in the

heart

Function is to pump blood (involuntary)

Cells attached to other cardiac muscle cells at intercalated disks

Cells are striated

One nucleus per cell Figure 3.19c



Smooth muscle Involuntary muscle

Surrounds hollow organs

Attached to other smooth muscle cells

No visible striations

One nucleus per cell Figure 3.19a

Nervous TissueNervous Tissue


Neurons and nerve support cells

Function is to send impulses to other areas of the body

Irritability

Conductivity Figure 3.20

Tissue RepairTissue Repair


Regeneration Replacement of destroyed tissue by the

same kind of cells

Fibrosis Repair by dense fibrous connective tissue

(scar tissue)

Determination of method Type of tissue damaged

Severity of the injury

Events in Tissue RepairEvents in Tissue Repair


Capillaries become very permeable Introduce clotting proteins

Wall off injured area

Formation of granulation tissue

Regeneration of surface epithelium

Regeneration of TissuesRegeneration of Tissues


Tissues that regenerate easily Epithelial tissue

Fibrous connective tissue and bone

Tissues that regenerate poorly Skeletal muscle

Tissues that are replaced largely with scar tissue Cardiac muscle

Nervous tissue within the brain and spinal cord

Developmental Aspects of TissueDevelopmental Aspects of Tissue


Epithelial tissue arises from all three primary germ layers

Muscle and connective tissue arise from the mesoderm

Nervous tissue arises from the ectoderm

With old age there is a decrease in mass and viabililty in most tissues

Cells & Tissues. Introduction to Cells and Tissues Slide 3.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carry out all.

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