Human Bio Chapter 4

unicellular organism

simple, fragile organisms made up of only one cell;

dependent on immediate external environment for survival

multicellular organism

complex organisms made up of two or more cells;

able to seek out/maintain external environment conducive to survival

Tissues

groups of specialized cells with similar structure and common functions;

group together to form organs

Epithelial Tissues

Primary tissue that covers the body’s surface, lines internal cavities, and forms glands

Glands

epithelial tissues specialised to synthesize and secrete a product

Exocrine glands

secrete product into a hollow organ(duct);

Ex. saliva, sweat, stomach acid

Endocrine glands

secrete hormones into blood stream;

Ex. Thyroid gland

Simple Epithelium

single layer of cells, thin layer, molecules pass through it easily

Stratified Epithelium

multiple layers (strata) of cells, thicker layer, provides protection

Squamous Epithelium

1 or more layers of flattened cells

Ex. skin, lining of blood vessels, lungs, mouth, throat, and vagina

Cuboidal Epithelium

cube shaped cells;

Ex. kidney tubule and covering of ovaries

Columnar Epithelium

tall/rectangular cells that secrete mucus to lubricate and trap bacteria, viruses,etc.;

Ex. digestive tract, some reproductive organs and larynx

Basement membrane

Non-living extracellular material that anchors epithelial tissues to underlying connective tissue

Cell junctions

connect epithelial cells to each other;

protein

Tight Junctions

seals plasma membranes so nothing can pass between them

Adhesion Junctions

allow some movement of materials between cells and provide structural support, anchoring cells together;

can stretch and bend

Gap Junctions

permit movement of ions or water between two adjacent cells

Connective Tissue

supports soft organs and holds body together;

stores fat and produces blood cells

Fibrous Connective Tissue

connects body parts with strength, support and flexibility

Collagen Fibers

a protein that confers strength and is slightly flexible

Elastic Fibers

can stretch without breaking:

aka protein elastin

Reticular Fibers

thin interconnecting fibers of collagen;

internal structural framework

Fibroblasts

responsible for producing and secreting proteins that compose collagen, elastic and, reticular fibers.

Cartilage

transitional tissue from which bone develops

Bone

specialized connective tissue that contains only a few living cells

Adipose Tissue

loose connective tissues highly specialized for fat storage;

most volume occupied by adipocytes (fat cells)

Muscle Tissue

cells specialized to shorten/contract, resulting in movement;

composed of muscle fibers

Skeletal Muscle Tissue

connects to tendons, attached to bones';

when it contracts, body parts move

Cardiac Muscle Tissue

found only in the heart

Smooth Muscle Tissue

surrounds hollow organs and tubes

Nervous Tissue

generates and transmits electrical impulses;

includes brain and spinal cord

Neuron

brain cell;

made up of the body, nucleus, dendrites and axon

Organ

composed of two or more tissue types that perform specific functions

Organ System

group of organs;

serve broad functions

Tissue Membranes

layer of connective tissue and layer of epithelial cells that line body cavities and form skin

Integumentary System

Skin, hair, nails, and glands

Epidermis

outer layer of skin’s epithelial tissue

Dermis

inner layer of connective tissue

Keratinocytes

produce tough waterproof protein called keratin

melanocytes

produces a dark brown pigment called melanin

Interstitial Fluid

fluid between body cells

negative feedback

control mechanism;

a change in the controlled variable triggers a series of opposing events that negates initial change returning to normal value

Positive Feedback

change in controlled variable creates events that amplify original change;

relatively uncommon in living organisms;

Ex. birth contractions

Controlled Variable

physical or chemical property may vary and must be controlled to maintain homeostasis;

Ex. blood pressure, body temperature, glucose

Sensor

monitors current values of controlled variable and sends info to control center

Control Center

receives input from sensor and compares to correct value (aka set point) sends signals to an effector

Effector

takes necessary action to correct imbalance in accordance with signals from control center