anatomy exam 2

tissues

groups of cells similar in structure that perform common or related function

histology

study of tissues

microscopy

tissue is fixed (preserved), cut (sliced thin enough to transmit light or electrons), and stained (enhances contrast)

4 types of primary tissues

epithelial, connective, muscle and nerve tissues

epithelial tissue

a sheet of cells that covers body surfaces or cavities, 2 types are covering and lining epithelia and glandular epithelia

covering and lining epithelia

on external and internal surfaces (ex. skin)

glandular epithelia

secretory tissue in glands (ex. salivary glands)

epithelial tissue functions

protection, absorption, filtration, excretion, secretion, sensory reception

five characteristics of epithelial tissue

polarity, specialized contacts, supported by connective tissues, avascular but innervated, regeneration

apical surface

upper free side, is exposed to surface or cavity. most are smooth but some contain microvilli

basal surface

lower attached side, faces inwards towards the body. attaches to basal lamina

basal lamina

an adhesive sheet that holds basal surface of epithelial cells to underlying cells

special contacts

epithelial tissues need to fit closely together, many form continuous sheets. binds adjacent epithelial cells together

lateral contacts include

tight junctions, desmosomes and gap junctions

connective tissue support

all epithelial sheets are supported by connective tissue

reticular lamina

deep to basal lamina, consists of network of collagen fibers

basement membrane

made up of basal and reticular lamina, reinforces epithelial sheet, resists stretching and tearing, defines epithelial boundary

how do cancerous epithelial cells differ

they penetrate the epithelial boundary and invade underlying tissues

avascular but innervated

no blood vessels in epithelial tissue, must be nourished by diffusion from underlying connective tissues

regeneration

some cells are exposed to friction, some to hostile substances resulting in damage. must be replaced requiring adequate nutrients and cell division. original function restored

all epithelial cells have

2 names

simple epithelia

absorption, secretion, filtration, very thin

stratified epithelia

two or more layers of cells

shapes of epithelial cells

squamous, cuboidal, columnar

squamous cells

flattened and scale like, nucleus flattened

cuboidal cells

boxlike, nucleus round

columnar cells

tall and column shaped, nucleus elongated

simple squamous epithelium

cells flattened laterally, cytoplasm sparse, function where rapid diffusion is priority (e.g., kidney and lungs) also in endothelium and mesothelium

endothelium

the lining of lymphatic vessels. blood vessels, and heart

mesothelium

the epithelium of serous membranes in the ventral body cavity

simple cuboidal epithelium

single layer of cells, secretion, absorption, forms walls of smallest ducts of glands and many kidney tubules

simple columnar epithelium

single layer of tall, closely packed cells, absorption, secretion

pseudostratified columnar epithelium

cells vary in height, cell nuclei at different levels, appears stratified but it is not, secretion and absorption

stratified epithelial tissues

two or more cell layers, regenerate from below, more durable than simple epithelia, protection is major role

stratified squamous epithelium

most widespread of stratified epithelia, free surface squamous, deeper layers cuboidal or columnar. located for wear and tear, those furthest from basal layer (less viable)

stratified cuboidal epithelium

quite rare, found in some sweat and mammary glands, typically two cell layers thick

stratified columnar epithelium

limited distribution in body, small amounts in pharynx, male urethra, and lining some glandular ducts. also occurs at transition areas between two other types of epithelia. only apical layer columnar

transitional epithelium

forms lining in hollow organs, basal layer cells are cuboidal or columnar, ability to change shape with stretch

gland

one or more cells that makes and secretes an aqueous fluid called a secretion

endocrine glands

ductless glands, internally secreting (ex. hormones), secretes hormones that travel through lymph or blood to their specific target organs

exocrine glands

secrete products into ducts, externally secreting (ex. sweat, mucous, saliva), more numerous than endocrine glands

unicellular exocrine glands

goblet cells and mucous cells, found in epithelial linings of intestinal and respiratory tracts. all produce mucin

multicellular exocrine glands

composed of a duct and a secretory unit, usually surrounded by supportive connective tissue. supplies blood and nerve fibers

connective tissue

most abundant and widely distributed of primary tissues

4 main classes of connective tissue

connective tissue proper, cartilage, bone, blood

major functions of connective tissue

binding and support, protecting, insulating, storing reserve fuel, transporting substances (blood)

characteristics of connective tissue

have common origin: mesenchyme (embryonic tissue)

have extracellular matrix

structural elements of connective tissue

ground substance, fibers, cells

ground substance of connective tissue

unstructured material that fills space between cells , components include interstitial fluid, cell adhesion proteins, proteoglycans

proteoglycans

sugar proteins, trap water in varying amounts, affecting viscosity of ground substance

connective tissue fibers

collagen, elastic fibers, reticular

collagen fibers

strongest and most abundant type. tough; provides high tensile strength

elastic fibers

networks of long, thin, elastin fibers that allow for stretch and recoil

reticular fibers

short, fine, highly branched collagenous fibers. branch, forming networks that offer more give

adipocytes

fat cells that store nutrients

mast cells

release histamine (play role in inflammatory response)

leukocytes

white blood cells, tissue response to injury, initiate local inflammatory response against foreign microorganisms they detect

types of white blood cells

neutrophils, eosinophils, lymphocytes

macrophages

phagocytic cells that "eat" dead cells, microorganisms; function in immune system

connective tissue proper

all connective tissues except bone, cartilage and blood. divided into two subclasses: loose CT and dense CT

loose connective tissues

areolar, adipose, reticular

dense connective tissue

dense regular, dense irregular, elastic

areolar connective tissue

most widely distributed, support and bind other tissues, provide reservoir of water and salts, defend against infection, story nutrients as fat, fibroblasts, loose arrangement of fibers, when enflamed soaks up fluid

universal packing material between other tissues

areolar connective tissues

edema

when inflamed soaks up fluid

adipose tissue

white fat and brown fat

white fat

similar to areolar but greater nutrient storage, cell is adipocyte, scanty matrix, richly vascularized, shock absorption, insulation and energy storage

adipocyte

white fat cell that stores nutrients

brown fat

use lipid fuels to heat bloodstream not to produce atp

reticular connective tissue

resembles areolar but fibers are reticular fibers, fibroblasts called reticular cells, supports free blood cells in lymph nodes, the spleen and bone marrow

dense regular connective tissue

closely packed bundles of collagen fibers running parallel to direction of pull, fibroblasts manufacture fibers and ground substance, few cells, poorly vascularized

dense irregular connective tissue

same elements but bundles of collagen thicker and irregularly arranged, resists tension from many directions

examples of dense irregular connective tissue

dermis, fibrous joint capsules, fibrous coverings of some organs

elastic connective tissue

dense regular tissue with a lot of elastic fibers, some ligaments very elastic, many of larger arteries have in walls

cartilage

chondroblasts and chondrocytes, tough yet flexible, lacks nerve fibers, up to 80% water, avascular

three types of cartilage

hyaline, elastic and fibrocartilage

where is hyaline cartilage found

costal cartilage of ribs

where is elastic cartilage found

external ear

where is fibrocartilage found

intervertebral discs

osseous tissue

bone, supports and protects body structures, stores fat and synthesizes blood cells in cavities, more collagen than cartilage, osteoblasts osteoclasts osteocytes and osteons. richly vascularized

osteoblasts purpose

produce matrix (blasts build)

osteoclasts purpose

break down matrix (clasts collapse)

osteons

structural units

blood

most atypical connective tissue, red blood cells most common type, also contains WBC and platelets, fibers are soluble proteins that precipitate during blood clotting, function is transport

function of blood

transport

muscle tissue

highly vascularized, responsible for most types of movement

3 types of muscle tissue

skeletal muscle tissue, cardiac muscle tissue and smooth muscle tissue

skeletal muscle tissue

found in skeletal muscle, voluntary

cardiac muscle tissue

found in walls of the heart, involuntary

smooth muscle tissue

mainly in walls of hollow organs other than heart, involuntary

nervous tissue

main component of nervous system, brain, spinal cord, and nerves. regulates and controls body functions

neurons

specialized nerve cells that generate and conduct nerve impulses

neuroglia

supporting cells that support, insulate and protect neurons

covering and lining membranes

composed of at least two primary tissue types, an epithelium bound to underlying connective tissue proper

3 types of covering and lining membranes

cutaneous, mucous, serous

cutaneous membranes

skin, keratinized stratified squamous epithelium attached to a thick layer of connective tissue (dermis and epidermis). dry membrane

mucous membranes

moist membranes that secrete mucous, mucosa indicates location not cell composition, all called mucosae, epithelial sheet lies over layer of connective tissue called lamina propria

serous membranes

serosae found in closed ventral body cavity, simple squamous epithelium resting on thin areolar connective tissue

parietal serosae

line internal body cavity walls