2. Epithelia

Question 1

what is epithelia

Answer 1

comprise sheets of cells, with one or more layers, resting on a basement membrane. They form barriers for protection, absorption and secretion

Question 2

simple epithelia

Answer 2

single layer on a basement membrane

Question 3

stratified (compound) epithelia

Answer 3

two or more layers of cells on a basement membrane

Question 4

simple squamous epithelium

Answer 4

single layer of flattened plate-like cells on a basement membrane
parallel oval nuclei
lines inside of blood vessels and outside of lungs and abdominal organs

Question 5

simple cuboidal epithelia

Answer 5

single layer of cells with similar height and width on a basement membrane
central spherical nuclei
line kidney tubules, small ducts

Question 6

simple columnar epithelium

Answer 6

single layer of cells
taller than they are wide, on a basement membrane
line the stomach, intestines, and uterus
may or may not have cilia or microvilli

Question 7

microvilli

Answer 7

microscopic projections on luminal surface of absorptive cells, increase surface area, intestinal brush border

Question 8

cilia

Answer 8

microscopic motile projections on luminal surface of cells, respiratory tract, reproductive tract

Question 9

stratified epithelia

Answer 9

protective function
many layers of cells
continually being worn down, worn-away cells replaced from below
found at sites subject to abrasive forces

Question 10

stratified squamous non-keratinising epithelium

Answer 10

multiple layers of cells on a basement membrane
mature surface layers are plate-like squames
waterproof layer of keratin, present in skin

Question 11

Pseudostratified epithelium

Answer 11

single layer of cells of variable height, mimicking multiple layers on a basement membrane
all cells in contact with basement membrane
lines the conducting airways

Question 12

Urothelium is specialised stratified epithelium

Answer 12

surface layer of umbrella cells
cells between umbrella cells appear 3-7 layers thick and this layer is pseudostratified
sometimes called transitional epithelium
lines the collecting part of the urinary tract

Question 13

basement membrane

Answer 13

always present - usually cannot see it
infer presence - difference between epithelium and underlying connective tissue
composed of several extra-cellular proteins including collagen IV and Fibronectin
essential for the proper functioning and survival of the epithelium
can be seen if stained with PAS

Question 14

occluding /tight junctions

Answer 14

band-like fusions between cells that are impervious to most molecules, prevent diffusion between cells

Question 15

desmosomes (anchoring/adherent) junctions

Answer 15

plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells, spread forces across several cells

Question 16

Gap (communicating) junctions

Answer 16

electrical junctions that permit the transfer of small molecules, electrically couple adjacent cells

Question 17

which two proteins are principally involved in the generation of ciliary movement

Answer 17

tubulin and dynein

Question 18

a gland secretes by shedding individual cells. what type of secretion is this?

Answer 18

holocrine

Question 19

what is the main purpose of tight junctions in the epidermal lining of the gut

Answer 19

to hold the cells together to prevent large molecules from passing between them and gaining access to the interior of the body
acts as a barrier and can establish a gradient for the absorption of secretion of molecules from or into the gut
only water and some selected small molecules are able to breach this barrier