Epithelial Cell surface specializations

Question 1

Types of apical surface cell specializations

Answer 1

1) cilia
2) microvilli
3) stereocilia

lumen

Question 2

Types of plasma membrane cell specializations (later and basal surface)

Answer 2

1) tight junction
2) adheren junction
3) desmosome
4) gap junctions

5) hemidesmosomes

blood

Question 3

Cilia key features

Answer 3

motile–> propel fluid
projects into lumen

LENTH OF CILIA = LENGTH OF NUCLEUS

Question 4

microvilli key features

Answer 4

increase SA for absorption (ie. gut)

center made of actine

MICROVILLI ARE SMALLER (nuclear are longer)

Question 5

stereocilia

Answer 5

LONG projections

longer stereocilia than nuclei

increase SA absorption

Question 6

Tight junction features

Answer 6

form seal

how thick it is, alters how permeable it is

maintains the different compositions between apical and basolateral membranes

kissing space: tighter tight junction = more lines

Question 7

gap junctions

Answer 7

communicating between cells

permit flux of SMALL molecules like ions, sugars (NOT proteins)

pores that have two sides connecting in middle (open, twist, close like a camera)

Question 8

adherens junctions

Answer 8

cell shape and motility

attach to actin cytoskeleton

create adhesion belt with cadherins

Question 9

Desmosomes

Answer 9

bring together TWO plasma membranes

intermediate filaments

have a core and plaque

increased in cells with increased mechanical stress

Question 10

Hemidesmosomes

Answer 10

bind intermediate filaments to basal membrane

Integrins: heterodimers

PULL whole segment of the cell