Lecture 6

Question 1

location of epithelial cell specializations

Answer 1

intercellular surfaces, luminal surfaces, basal surfaces

Question 2

types of specializations at intercellular surfaces

Answer 2

occluding, adhering, and communicating junctions

Question 3

types of specializations at luminal surfaces

Answer 3

cilia, microvilli, stereocilia

Question 4

types of specializations at basal surfaces

Answer 4

basement membrane and hemidesmosomes

Question 5

function of tight junctions

Answer 5

seals neighboring cells together in epithelial sheet to prevent leakage of molecules between them

Question 6

function of adhering junctions

Answer 6

joins an actin bundle in one cell to a similar bundle in a neighboring cell - anchor cystoskeleton and bind epithelial cells together

Question 7

function of desmosome

Answer 7

joins the intermediate filaments in one cell to those in a neighbor

Question 8

function of gap junction

Answer 8

forms channels that allow small water soluble molecules (Ca2+, cAMP, pH) between cells

Question 9

function of hemidesmosome

Answer 9

anchors intermediate filaments in a call to the basal lamina

Question 10

where are tight junctions located

Answer 10

directly below luminal/apical surface

Question 11

types of adhering junctions

Answer 11

zonula adherens (also just called adhering junctions)
desmosomes (macular adherens)

Question 12

location of adhering junctions (zonula adherens)

Answer 12

deep to zonula occludens (tight junction)

Question 13

location of desmosomes (macula adherens)

Answer 13

deeper than zonula adherens

Question 14

where are desmosomes often found

Answer 14

stratified squamous cells

Question 15

function of desmosomes

Answer 15

structural integrity (REMEMBER THESE ARE A TYPE OF ADHERING JUNCTION)

Question 16

composition of desmosomes in three locations

Answer 16

intercellular - desmocollins
transmembrane - desmogleins
plaque - desmoplakin, keratin

Question 17

gap junction location

Answer 17

below junctional complex

Question 18

cell specializations at basal surface

Answer 18

hemidesmosomes and basement membrane

Question 19

hemidesmosome function

Answer 19

anchorage of cytoskeleton at base of cell to basement membrane

Question 20

hemidemosomes contain what kind of filaments

Answer 20

intermediate filaments (tonofilaments or cytokeratins)

Question 21

function of basement membrane (6)

Answer 21

1. physical support
2. cell attachment
3. selective barrier
4. growth, differentiation
5. regeneration
6. special functions ex ultrafiltration in kidney, blood air barrier (lung), tumor metastasis

Question 22

composition of basement membrane (6)

Answer 22

1. type 4 collagen (ONLY IN BM!!!!)
2. laminin (binds collagen to BM)
3. proteoglycans
4. entactin (binds laminin to type 4 collagen)
5. fibronectin (binds integrins of plasma membrane, produced by fibroblasts of the connective tissue)
6. type 7 collagen (binds basal lamina to subjacent collagen)

Question 23

how many microvilli per cell

Answer 23

3000 to increase SA for absorption

Question 24

structure of cilia

Answer 24

central microtubule pair surrounded by 9 doublets inserted into basal body composed of 9 microtubule triplets

Question 25

function of cilia

Answer 25

clean airways, transport ovum

Question 26

how is movement achieved with cilia

Answer 26

longitudinal -- movement of doublets relative to one another, ATPase, active

Question 27

sperm moved by

Answer 27

microtubules, cilia

Question 28

microvilli composition

Answer 28

20-30 actin filaments

Question 29

how is movement achieved with microvilli

Answer 29

contract and elongate, no ATPase

Question 30

stereocilia

Answer 30

misnamed, actually made of actin so really villi

Question 31

where are stereocilia found

Answer 31

male reproductive tract, epididymus

Question 32

movement of stereocilia

Answer 32

not active, no ATPase