Epithelial cells

Question 1

Epithelia

Answer 1

present throughout the body
important components in many organ systems
form boundaries
functions in met, transport, secretion, absorption, protection

Question 2

thickness of tissue sample

Answer 2

5um - 2d

Question 3

effect of plane running obliquely to villus

Answer 3

creates appearance of an isolated island of tissue

Question 4

shape of nucleus

Answer 4

reflect shape of cell

Question 5

what is visible at higher magnification

Answer 5

the nucleus but not the cell boundaries

Question 6

SI

Answer 6

in centre - lumen contains partly digested food
epi stain pink with purple nuclei
pale staining region with bv and lymph ducts
further out - muscular laye r (pink) for peristalsis

Question 7

villus at x40

Answer 7

cells in single layer - nuclei alongside each other - simple epi
base of cell attached to thin fibrous layer - basal lamina/basement membrane
columnar cells
between epi - bulbous cells with pale cytoplasm - goblet

Question 8

function of villus epi

Answer 8

absorption of products of digestion

Question 9

apical surface of enterocytes

Answer 9

facing lumen of intestine
brush border - zone w/o organelles, see striations
close packed extensions to increase SA - microvilli 1000x smaller than villi

Question 10

enterocyte junctions

Answer 10

no gaps

otherwise there would be diffusion of undesirable contents of lumen into body

Question 11

description of epi lining intestine

Answer 11

simple columnar absorptive epi with goblet cells

Question 12

glands

Answer 12

when lumen is small - epi is forming glands/ducts
tubular structure into which cells secrete things which diffuse along tubes to tehir destination
crypts - simple tubes and closed ends
near end - secretory cells - Paneth cells recognised by secretory granules - positioned asymettrically in cell so they release their contents at apical surface onto crypts

Question 13

type of glands

Answer 13

crypts - simple tubular glands because single closed tube
if branched - gland would be a compound
if secretory cells restricted to regions with round shape at ends - acinar ot alveolar gland (acinus or alveolar are secretory regions and rest of system is ducts)

Question 14

mesentery

Answer 14

thin layer
attaches intestines to rest of body
allow intestine in abdominal cavity to have blood and nervous supply - allow intestine to be mobile in peristalsis

Question 15

low power of mesentery

Answer 15

some places thin
others have bv surrounded by fat
simple epithelium around tissue
squamous - reflected in nuclei

Question 16

function of epithelium around mesentery

Answer 16

forms a boundary

Question 17

oesophagus

Answer 17

epi lining central lumen 
stratified 
basal cells purple 
higher up pink 
near lumen - v pale 
through layers cells diff shape - basal = round, closer to the lumen - squamous

Question 18

purpose of epi of oesophagus

Answer 18

prevent damage - human swallow dangerous things
partly chewed food - abrasive bones or veg fragments
stratified means if surface cells damaged - layers beneath can function and divide to replace those lost

Question 19

skin

Answer 19

stratified squamous epithelium
waterproof to prevent cells beneath drying out
surface cells cornified (died) - keratin left containing intermediate filaments - absorbs oily secretions = waterproof
epidermis
cells are keratinocytes
most basal - stratum basale - cuboidal, on basal lamina
stem cells in this layer produce cells for the upper layers - differentiate and replace cells from surface. melanocytes in this layer

Question 20

stratum spinosum

Answer 20

apical to stratum basale in skin

few layers - spikey appearance

Question 21

stratum granulosum

Answer 21

apical to stratum spinosum

contain numerous granules

Question 22

stratum corneum

Answer 22

dead - cornified during differentiation

no nuclei

Question 23

features in thin skin

Answer 23

hairs and follicules

Question 24

thick skin

Answer 24

in palms and soles
hair not present
stratum corneum thicker than in thin

Question 25

trachea

Answer 25

epi separate lumen from surrounding tissue including cartilage rings - red/purple
columnar cells
apical section - cilia - longer than brush border of intestine
goblet cells
pseudostratified - all attached to basal layer

Question 26

overall description of epithelium of trachea

Answer 26

pseudo-stratified columnar ciliated epithelium

Question 27

stratified columnar/cuboidal

Answer 27

not functionally important

Question 28

urinary epithelium

Answer 28

features of stratified and pseudostratified
transitional epi
highly impermeable to urine and stretch bladder as fills

Question 29

cell renewal

Answer 29

stem cells - in crypts in intestine
in stratified the stem cells are in basal layer adjacent to basal lamina
in simple epi - all cells capable of division