A&P Unit 2 (Epithelial)

what are the 4 major tissue types?

1. epithelial

2. connective

3. muscle

4. nervous

what are the functions of epithelial tissue?

• protects, covers, and lines

• filters biochemical substances

• absorbs nutrients

• provides sensory input

• manufacture secretions/excretions

secretion

substance that remains in the body

excretion

substance that leaves the body

what are 4 defining characteristics of epithelial cells?

1. they are polar

2. have lateral surfaces connected to neighboring cells by junctional complexes

3. they are avascular

4. most are innervated

how is an epithelial cell polar?

the cell has 2 different sides; apical and basal

what is an example of a junctional complex?

BBB- blood brain barrier

how is an epithelial cell avascular?

they lack blood vessels and capillaries, and rely on on underlying tissues for nutrients

what are the 3 major cellular junctions in epithelial cells?

1. tight junction

2. desmosome

3. gap junction

what does a tight junction do?

fusion of outermost layers of plasma, connecting adjoining cells; allows an organ no leakage

ex. of tight junctions

urinary bladder or digestive tract

what does a desmosome do?

strong, welded plaque, connecting adjacent cells; allows expansion

ex. of desmosomes

skin, heart, or uterus

what does a gap junction do?

linked by connexons, extend from cytoplasm of one cell to another; quick transport of ions & nutrients

what type of junction is this?

tight junction

what type of junction is this?

gap junction

what type of junction is this?

desmosome

ex. of gap junctions

GI tract, heart, or smooth muscle tissue

what is the basement membrane?

nonliving of fibers making up the foundation of the epithelial cell

what does the basement membrane do?

helps prevent the cell from being torn off by pressures like stretching or erosion

where can microvilli be found?

on epithelial tissue of the intestine; usually cells that secrete/excrete

where can cilia be found?

on epithelial tissue of the upper respiratory; move something along

what is keratin?

a protective, waterproof substance that fills epithelial cells of the skin

how do we classify epithelial cells?

1. number of layers of cells

2. shape of the cells

3. presence of surface specializations

number of layers of cells

simple= single layer

stratified= more than one layer

shape of the cells

squamous= flat and smooth

cuboidal= cube shaped

columnar= column shaped

presence of specializations

cilia, microvilli, keratin, etc

where would you find simple squamous?

lining surfaces involved in the passage of either gas or liquid

where would you find simple cuboidal?

sheltered regions of the body where secretion and absorption take place, like ovaries or glands

where would you find simple columnar?

GI tract from the stomach to the rectum

what 2 cells make up the lining of the gut?

absorptive and goblet cells

where would you find stratified squamous?

regions of the body subject to mechanical and chemical stress, like the mouth, esophagus, vagina, and rectum

where would you find stratified cuboidal?

excretory ducts, such as sweat, mammary, or salivary glands

where would you find stratified columnar?

rare, only in parts of the respiratory, digestive, and reproductive systems

what is psuedostratified columnar?

epithelial that is not truly stratified

which cell shape is this?

squamous

which cell shape is this?

cuboidal

which cell shapes is this?

columnar

what type of layering is this?

simple squamous

what type of layering is this?

simple cuboidal

what type of layering is this?

simple columnar

what type of layering is this?

stratified squamous

what type of layering is this?

pseudostratified

what is a gland?

a cell or group of cells with the ability to manufacture and discharge a secretion

how can we classify glands?

1. presence or absence of ducts

2. number of cells that compose them

3. complexity of the structure

4. type of secretion produced

5. how the secretion is stored or discharged

endocrine glands

do NOT have ducts

exocrine glands

DO have ducts

what is the ONLY unicellular exocrine gland that is ductless?

the goblet cell

what do goblet cells secrete?

mucin, found in the upper respiratory, GI tract, and conjunctiva

multiceullular exocrine glands

made of a secretory unit and duct

simple exocrine glands are __________, while compound exocrine glands are __________

unbranched, branched

merocrine glands

remain intact through secretion

apocrine glands

lose the apex of the cell through secretion

holocrine glands

are completely destroyed through secretion

serous secretions

are watery and contain a high concentration of enzymes

mucous secretions

are thick and composed of glycoproteins (mucus)

what are numbers 1-7?

1. simple alveolar

2. simple branched alveolar

3. compound alveolar

4. simple straight tubular

5. simple coiled tubular

6. simple branched tubularcompound tub