Levels of Organization The structures of the human body are organized into levels of increasing complexity. Chemical Cellular Tissue Organ System Organism
Dec 17, 2015
Levels of Organization
The structures of the human body are organized into levels of increasing complexity.
Chemical Cellular Tissue Organ System Organism
Feedback Systems
Aka feedback loop A cycle of events in which the status of a body
condition is continually monitored, evaluated, changed, re-monitored, re-evaluated, changed, re-monitored, re-evaluated…
Stimulus
Any disruption that causes a change in the controlled condition
Can be internal or external
Controlled Condition
Each monitored condition in the body Ex – heart rate, BP, BGL,
temperature…
Receptor
A body structure that sends information (input) to the control center in the form of nerve impulses or chemical signals
Control Center
Sets the range of values within which a controlled condition should be maintained, evaluated input from the receptors and send output to the effector
Effector
A body structure that receives output from the control center and produces a response or effect that changes the controlled condition
Negative Response Systems
Reverses a change in the controlled condition
Ex – If blood pressure is too high, your body works to lower it
Baroreceptors
Brain
Heart
Decrease Heart rate
Blood Pressure
Positive Feedback System
Operates to reinforce the initial change in the controlled condition Ex – Contractions of the uterus increase during
childbirth
Abdominopelvic Regions
9 smaller divisions of the abdominopelvic cavity to help describe the precise location of organs
Trace Elements
• The remaining 0.2% of the body’s mass is made of these 14 elements:– Al, B, Cr, Co, Cu, F, I, Mn, Mo, Se, Si,
Sn, V and Zn– Even though they are present in
REALLY small amounts, they are still essential to maintain homeostasis!
• Cation – a positive ion
• Anion – a negative ion
Free Radicals• An electrically charged ion or
molecule that has an unpaired electron in its outermost shell
• A free radical is unstable and destructive to nearby molecules
• They break apart other molecules in the body by either giving up their unpaired electron or by taking an electron from another molecule.
Antioxidants• Substances that inactivate oxygen
associated free radicals.• Consumption of antioxidants is though
to slow the pace of damage caused by free radicals.
• Dietary sources of antioxidants include selenium, beta-carotene and vitamins C and E. “The antioxidants will protect me…”
Electrolytes
• An ionic compound that breaks apart into cations and anions when dissolved is called an electrolyte because the resulting solution can conduct an electric current– Critical in controlling water
movement, maintaining acid/base balance and producing nerve impulses
Hydrogen Bonds• A VERY VERY strong interaction
between some polar molecules containing hydrogen
• A hydrogen atom in one molecule with a partial positive charge attracts a partial negative atom (F, O or N) from another molecule.
• About 5% as strong as an actual covalent bond
Inorganic Compounds
• Usually small• Lack carbon and/or hydrogen• Many contain ionic bonds• Examples:
– Water, oxygen, carbon dioxide, many acids, bases and salts
• Acids dissociate into H+ ions
• Bases dissociate into OH- ions
• Salts form ions that are not H+ or OH-
Buffer Systems
• Consist of a weak acid and a weak base that function to prevent drastic changes in the pH of body fluid by rapidly changing strong acids and bases into weak acids and bases
Body’s pH
• The pH range of blood is 7.35-7.45 (you need to know these exact numbers!)
• The body maintains pH through the use of buffer systems
Dehydration Synthesis
• 2 smaller molecules join together to form a larger molecule by removing a molecule of water
Hydrolysis
• Large molecules are broken down into smaller molecules by the addition of water
Review of Organic Compounds
• Carbohydrates– Building blocks = monosaccharides
• Lipids (Triglycerides)– Building Blocks = glycerol and fatty
acids• Proteins
– Building Blocks = amino acids
Carbohydrates
• Include sugars, glycogen, starches and cellulose
• Made from Carbon, Hydrogen and Oxygen
• Usually 1:2:1 ratio (CH2O)• Divided into groups based on size
Lipids (Fats)
• Made of Carbon, Hydrogen and Oxygen
• Proportion of Oxygen is usually lower than in carbohydrates
• Not as many polar bonds so they are not soluble in water
• Include triglycerides, phospholipids, steroids, fatty acids and fat soluble vitamins (A, D, E and K)
Protein
• Large molecules containing Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulfur
• Building Blocks are Amino Acids
Amino Acids
• Protein Structures– Primary– Secondary– Tertiary– Quaternary
Denaturation• If temperature, pH or ion
concentration is altered, a protein may unravel and lose it shape
• If a protein changes shape (is denatured) it is no longer functional because…– SHAPE DETERMINES FUNCTION!
Enzymes
• Protein Catalyst• A substance that can speed up a
chemical reaction without themselves being altered
• Names of enzymes generally end in -ase– Ex. Kinase, dehydrogenase, amylase
Nucleic Acids
• Named because they were first found in the nucleus of cells
• VERY VERY BIG• Contain C, H, O, N and P
• DNA and RNA
The Plasma Membrane
Flexible yet sturdy barrier composed mainly of phospholipids and proteins.
Called the “Fluid Mosaic Model”
Selective Permeability
The plasma membrane allows some substances to move into and out of the cell but restricts the passage of other substances
– Permeable to: lipid soluble molecules such as fatty acids, vitamins, steroids. Also small molecules such as water, oxygen and carbon dioxide
– NOT permeable to ions and charged or polar molecules such as glucose and amino acids
Communication Structures
Receptors– Integral proteins that recognize and bind to specific
molecules governing some cellular function Enzymes
– Membrane proteins that speed up chemical reactions in the cell
Cell Identity Markers– Molecules that allow the cell to recognize cells of its
own kind or to recognize and respond to potentially dangerous foreign cells.
Passive Processes
Transport of materials without the addition of extra cellular energy (ATP)
Tonicity of Body Fluids
Sodium Chloride concentration [NaCl] in body
cells is 0.9%
Active Processes
Cellular energy is used to transport substances up a concentration gradient
Sodium Potassium Pumps
Remove Na+ from the cell and transport K+ into the cell
Maintain concentration gradients necessary for osmotic balance and to generate electrical signals
Organelles
Specialized structures inside the cell with characteristic shapes and functions
Nucleus
Most cells have 1 nucleus– Mature Red Blood Cells have no nucleus– Skeletal Muscles are multinucleated
Gene Action: Protein Synthesis
2 basic steps:– Transcription – the genetic information in DNA base
triplets is copied into a complementary sequence of codons in a strand of mRNA
– Translation – mRNA codons associated with ribosomes direct the order of amino acids in a polypeptide
Nuclear Division
The duplicated chromosomes become exactly segregated (one set into each new nucleus).
Divided into 4 continuous stages:– Prophase, Metaphase, Anaphase, Telophase
http://www.cellsalive.com/mitosis.htm
Types of Tissues Epithelial Tissue
Covers body surfaces; lines body cavities, hollow organs and ducts; forms glands
Connective Tissue protect and supports the body and its organs,
binds organs together, stores energy reserves as fat, provides immunity
Muscular Tissue Generates the force needed to make body
structures move Nervous Tissue
Detects changes inside and outside the body and initiates and transmits nerve impulses that coordinate body activities to help maintain homeostasis
Epithelial Tissue
AKA Epithelium 2 types:
Covering and Lining Epithelium Forms the outer covering of the skin and
some internal organs. It also lines body cavities, blood vessels, ducts, and the interiors of many of the body systems.
Glandular Epithelium Makes the secreting portion of glands
Covering and Lining Epithelium – Cell Shapes
Squamous – flat cells that attach to each other like tiles Allows for rapid passage of substances through
them Cuboidal – cells are as tall as they are
wide, sometimes contain microvilli Function in Secretion and Absorption
Columnar – Taller than they are wide, sometimes contain microvilli or cilia Function in Secretion, Absorption and
Protection
Simple Epithelium
A single layer of cells found in areas where diffusion, osmosis, filtration, secretions and absorption occur
Non-cilliated Simple Columnar Epithelium
Contains absorptive cells and goblet cells Absorptive Cells – have microvilli to
increase surface area Goblet Cells – modified Columnar cells
that secrete mucus at the apical surface Lines most of the GI tract, ducts of
glands and gallbladder
Stratified Epithelium
Contains 2 or more layers of cells used for protection of underlying tissue in area where there is a lot of wear and tear
The name of the tissue depends on the shape of the cell on the apical layer
Transitional Epithelium
Varies in appearance depending on whether the organ it lines is distended or relaxed. Looks similar to stratified cuboidal
except the top layer is large and rounded
Transitional Cells have the ability to change shape from Cuboidal to Squamous and back as organs stretch
Glandular Epithelium Functions in Secretion A gland consists of one cell or a
group of cells
Endocrine Glands – secretions enter the interstitial fluid Hormones
Exocrine Glands – secrete their products into ducts (tubes) that empty at the surface of the covering/lining epithelium Mucus, oil, earwax, digestive enzymes
General Features of Connective Tissue
2 basic parts: Cells and Matrix
Matrix – material between widely spaced cells Consists of protein fibers and ground
substance Ground substance – material between cells
and fibers secreted by the cells and determine the tissue qualities
Connective Tissue Cells
Fibroblasts – large flat cells with branching processes. Migrate throughout connective tissue secreting the fibers and ground substance
Macrophages – develop from white blood cells. Surround and engulf material by phagocytosis
Mast Cells – alongside blood vessels that supply connective tissue. Produce histamine – a chemical that dilates blood vessels.
Adipocytes – “fat cells” store triglycerides.
TYPES OF BONES
There are 6 main types of bones:LongShortFlat IrregularSuturalSesamoid
Parts of a Long Bone
A typical long bone consists of:DiaphysisEpiphysesMetaphyesArticular CartilagePeriosteumMedullary CavityEndosteum
Cells
There are 4 major types of cells found in osseous tissueOsteoprogenitorOsteoblastOsteocyteOsteoclast
Compact Bone Tissue
Contains very few spaces
Forms the external layer of all bones and the diaphyses of long bones
Provides protection and support
Resists stress produced by weight and movement
Osteon
Organizational Unit of Compact Bone
Spongy Bone
Does not contain osteons
Made of trabeculae – an irregular network of thin columns of bone with many spaces in between
Trabeculae contain osteocytes within lacunae connected by canaliculi
Spongy tissue makes up most of flat, short and irregular bones
Forms most of the epiphyses of long bones
Found in a narrow rim around the medullary cavity
Intramembranous Ossification
Simpler of 2 methods of bone formation
Bones formed in this way includeFlat bones of the skullMandibleReplaces “soft spots”
Endochondral Ossification
Replacement of cartilage by boneMost bones in the body are formed in this
way
Surface Markings
Structural features adapted to specific functions on the surfaces of bones
Depressions and openings
Processes that form joints
Processes that tendons, ligaments, and other connective tissues attach
The Axial Skeleton
Includes:– Skull
• Cranium• Face
– Hyoid bone– Auditory ossicles– Vertebral column– Thorax
• Sternum• Ribs
The Skull
Contains 22 bones
8 Cranial Bones that enclose and protect the brain
14 Facial Bones that form the face
Sutures
An immovable joint
Found only between skull bones
Hold skull bones together
Fontanels 6 Membrane-filled spaces found between
cranial bones in infants Replaced with bone by intramembranous
ossification and become sutures “Soft Spot” on baby’s head FONTANELS
Anterior
Posterior
Anterolateral (2)
Posterolateral (2)
Regions of the Vertebrae
7 cervical vertebrae in the neck
12 thoracic vertebrae 5 lumbar vertebrae
supporting the lower back
1 sacrum (consists of 5 fused sacral vertebrae)
1 coccyx (consists of 4 fused coccygeal vertebrae)
Characteristics of Vertebrae
Cervical – transverse foraminaC1 – atlasC2 – axis (dens)C7 - vertebra prominens
Thoracic – facets for ribs; downward pointing spinous process (giraffe)
Lumbar – large; wide processes; (moose)
Sternum
Flat, narrow bone located in the center of the anterior thoracic wall
Also known as the breastbone
Consists of three parts
Ribs
Twelve pairs make up the sides of the thoracic cavity
Each rib articulates posteriorly with its corresponding thoracic vertebra
Appendicular Skeleton
Division of the skeleton consisting of the pectoral girdle, upper limbs, pelvic girdle and lower limbs.
Pectoral (Shoulder) Girdle
Upper Limb
Consists of 30 bones (all paired up)
Humerus in the arm Ulna and radius in the
forearm 8 carpals (each with its own
name), 5 metacarpals, and 14 phalanges in the hand
The carpals in the proximal (closest to the
radius/ulna) row are the: Scaphoid, Lunate,
Triquetrum, and Pisiform
The carpals in the distal row are the: Trapezium,
Trapezoid, Capitate, and Hamate
Pelvic (hip) Girdle
Functions: Support for vertebral column Protect pelvic organs Attach lower limbs
Coxal Bones: Hip bones 3 parts: Pubis, Ilium and Ischium
Coxal Bones
Pubis – anterior portion Joined by pubic symphysis
Ilium – superior portion Iliac Crest – ridge at the top of
the ilium Ischium – inferior portion
Acetabulum – socket for the head of the femur
Obturator Foramen – hole formed by the ischium and pubis
LOWER LIMB
Includes the thigh, leg, ankle, foot and toes
30 bones in each Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges
Tarsals
7 Ankle Bones Posterior: Talus
and Calcaneus
Anterior: cuboid, navicular and 3 cuneiform
Movements at Synovial Joints
Gliding Flexion/Extension Abduction/Adduction Circumduction Rotation
Protraction/Retraction Inversion/Eversion Supination/Pronation Dorsiflextion/Plantar Flexion Elevation/Depression