Cells & Tissue - Epithelia

Question 1

what are the functions of epithelial tissue?

Answer 1

• cells that cover body surfaces
• lines hollow organs, cavities, and ducts
• forms the glands of the body

Question 2

the cells of an epithelium are?

Answer 2

1. Arranged in continuous sheets as single or multiple layers of cells
2. Held together by a variety of cell junctions

Question 3

what are the different cell junctions?

Answer 3

tight junctions

adherens junctions

gap junctions

desmosomes

hemidesmosomes

Question 4

what are the key functions of epithelial tissues?

Answer 4

selective barriers (limit or alter/aid transfer) of molecules in parts of the body

secretory (releases materials) onto a free surface

protective - especially from abrasions

Question 5

what are the three different surfaces of epithelial cells?

Answer 5

apical

lateral

basal

Question 6

what are the tight, adherens, and desmosome junctions?

Answer 6

structural components that aid in keeping cells adjacent to each other

Question 7

what are the 2 major cytoskeleton structures?

Answer 7

microfilaments

intermediate filaments

Question 8

what protein is the microfilament composed of?

Answer 8

actin

Question 9

what is the intermediate filaments composed of?

Answer 9

keratin

Question 10

what is the structure and function of microfilaments?

Answer 10

structure -
bundles beneath cell membrane and cytoplasm

function - 
strength 

alters cell shape

links cytoplasm to membrane

tie cells together

muscle contraction

Question 10

what is the structure and function of microfilaments?

Answer 10

structure -
bundles beneath cell membrane and cytoplasm

function - 
strength 

alters cell shape

links cytoplasm to membrane

tie cells together

muscle contraction

Question 11

what is the function of the intermediate filament?

Answer 11

strength

moves materials through cell cytoplasm

Question 12

where can you find tight junctions in the body?

Answer 12

stomach

intestines

bladder

Question 13

what two key proteins are involved with tight junctions and what do they do?

Answer 13

claudins

occludins

weld cells together

Question 14

what are the 2 primary functions of the tight junctions

Answer 14

1. joins the cytoskeletons of adjacent cells e.g. via ZO-1 to actin
2. keeps cell polarity by preventing migration of proteins between apical and basal surfaces (controls materials such as ions from traversing down into other spaces)

Question 15

describe adherens junctions? (structure)

Answer 15

• have a plaque layer of proteins on the inside of the cell to join actin to cadherins
• cadherins span the gap
• catenins link to the cadherins to actin (links cytoplasm in 2 cells)

Question 16

what is the pf of adherens junctions?

Answer 16

adherens junctions prevent cell separation from tension forces like in contractions