tissues, organs, and homeostasis

what are the four levels of organization?

1. cells

2. tissues

3. organs

4. organ systems

how many different cell types do humans have?

humans have 210 different cell types (bodies of vertebrates have different cell types)

cell

the smallest division of life

all life is cellular

all cells come from preexisting cells

tissue

groups of cells that are similar in structure and function

organ

combinations of different tissues that form a structural and functional unit

organ system

groups of organs that cooperate to perform the major activities of the body

how many principal organ systems does the vertebrate body contain?

11

what is the body plan of all vertebrates?

a tube within a tube

inner tube

digestive tract

outer tube

main vertebrate body

supported by a skeleton

outermost layer = skin and its accessories

four primary tissues

epithelial, connective, muscle, nervous

epithelial tissue

covers exposed surfaces

all germ layers

protective

epithelial cells

tightly bound together

replaced

attach to underlying connective tissues by a fibrous membrane

epithelium has polarity

basal surface

secured side

apical surface

free side (exposed)

epithelial type one layer

one layer allows for diffusion, absorption, and secretion

epithelial type several layers

several layers create a dense barrier to abrasion and chemicals

epithelial types cell size/shape:

flat, cubed, thick

flat

materials diffuse through

cubed

absorb and secrete moderately

thick

absorb, secrete, and process chemicals at the greatest rate

how do glands form?

form from invaginated epithelia

exocrine gland

connected to epithelium by a duct

endocrine gland

ductless secretions (hormones) enter blood

connective tissues

derive from embryonic mesoderm

abundant extracellular material

connective tissue proper

loose, dense, adipose

special connective tissue

cartilage, bone, and blood

what do connective tissues consist of?

matrix = extracellular material

fibroblasts

cells that produce and secrete protein fibers in extracellular matrix

loose connective tissue

gel-like substance

protein fibers

dense connective tissue

less gel

more collagen

fibers parallel (tendons, ligaments)

fibers in different directions (dermis, whites of eyes)

adipose cells

fat cells

occur in loose connective tissue

cartilage

chondrocytes = cartilage cells

matrix = chondroitin, collagen/elastin fibers

bone

osteocytes = bone cells

hardened

calcium slats around collagen fibers

blood

extracellular material is fluid plasma

smooth muscles

walls of blood vessels

visceral organs

mono-nucleated

involuntary

skeletal muscles

attached to bone by tendons

long cells

multi-nucleated

striated

voluntary

cardic muscles

smaller, interconnected cells in heart only

mono-nucleated

intercalated disks

muscle cells form a single functioning unit

walls of heart

what are the three parts of the neuron?

1. cell body

2. dendrites

3. axon

cell body of neuron

contains the nucleus

dendrites of neuron

highly branched extensions

conduct electrical impulses toward cell body

axon of neuron

single cytoplasmic extension

conducts impulses away from cell body

neuroglia

do not conduct electrical impulses

support and insulate neurons

eliminate foreign materials

insulating cover

homeostasis

dynamic constancy of the internal environment

negative feedback

loops often oppose each other to produce finer degree of control

antagonistic effectors

increasing activity of one effector is accompanied by decrease in the other

positive feedback

do not maintain homeostasis

response is cumulative

generally part of some larger mechanism that does

what are the two major aspects of size?

surface area: area covering an object

volume: space the object takes up

how do the rates of surface area and volume compare?

if you double surface area you triple volume

how does size have an impact?

mechanical demands on support structures

nutrient absorption rate

heat gain and loss

gas exchange

communication and integration body stystems

nervous

sensory

endocrine

support and movement body systems

musculoskeletal system

skeletal system

muscular system

regulation and maintenance body systems

digestive

circulatory

respiratory

urinary

defense body systems

integumentary system

lymphatic/immune system

reproduction and development body systems

reproductive system