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