Surface Epithelium

Question 1

define contiguous cells

Answer 1

cells that form linings that cover most body surfaces, cavities or tubes

Question 2

what are functions of epithelial tissue

Answer 2

protection (skin), transcellular transport (with selective permeability), secretion (mucus precursor, hormones), absorption (intestine), sensations (taste buds, retina), immune defense (house cells of immune system, and physical barrier)

Question 3

describe the structure of epithelial tissue

Answer 3

apical + basal surfaces, tight junctions between cells, resting on basement membrane- attaches epi cells to connective tissue

Question 4

is there a lot/little extracellular space and matrix in epithelial tissue

Answer 4

little ECM or space

Question 5

define brush border

Answer 5

fuzzy appearance that villi give epi cells i.e intestine or kidney

Question 6

define motile cilia

Answer 6

allow movement by pushing substances i.e in trachea mucus

Question 7

what are the two sections of the basement membrane

Answer 7

basal lamina, lamina reticularis

Question 8

function of basal lamina?

Answer 8

molecular filter- prevent substances entering epithelium

Question 9

function of lamina reticularis

Answer 9

fixes lamina densa to underlying connective tissue

Question 10

which part of the basement membrane is avascular

Answer 10

lamina reticularis

Question 11

what are the two subsections of the basal lamina

Answer 11

lamina lucinda and lamina densa

Question 12

how thick are the lamina lucinda and densa

Answer 12

50nm

Question 13

what are the lamina lucinda and densa made of

Answer 13

lucinda- glycoproteins- laminin and intactin

densa- type 4 collagen

Question 14

how are epithelial tissue/cells classified?

Answer 14

according to cell layers, morphology and polarity + surface specialisation

Question 15

two classification categories for number of cell layers

Answer 15

simple or stratified

Question 16

classification categories for cell morphology

Answer 16

squamous, cuboidal, columnar

Question 17

classification categories for polarity and surface specialisation

Answer 17

polarised cells- have apical domain and basolateral domain where the apical domain faces a lumen and the basolateral domain is in contact with the basal lamina

Question 18

write a note on simple squamous epithelium (structure, function, location)

Answer 18

thin single layer of flat cells, rapid diffusion (O2, CO2, fluids, ions), air sacs of lungs, kidney tubules, blood vessel linings

Question 19

write a note on simple cuboidal epithelium (structure, function, location)

Answer 19

single layer of cube shaped cells- large nucleus. rapid substance diffusion. renal tubules, resp passages, ducts of glands, thyroid glands, covering of ovary

Question 20

write a note on simple columnar epithelium (structure, function, location)

Answer 20

single layer rectanglular shaped cells- nuclei in basal portion of cell. can have microvilli or cilia on apical plasma membrane. microvilli = small intestine, cilia = uterine tubules/parts of resp tract

Question 21

what are the three categories of stratified squamous epithelium

Answer 21

kertatinized, non keratinized and parakeratinised

Question 22

describe keratinized stratified squamous epithelium

Answer 22

these cells are dead and lack nuclei- filled with keratin . resist friction and impermeable to water, i.e outer layers of skin

Question 23

describe non keratinized stratified squamous epi cells

Answer 23

retain nuclei and are still alive. found in areas where surface must be moist or wet like the mouth or throat, vagina

Question 24

describe parakeratinised stratified squamous epithelium

Answer 24

surfacemost cells retain their nuclei but are pyknotic meaning the nuclei are undergoing necrosis or apoptosis

Question 25

stratified cuboidal epi structure and function

Answer 25

two cell layers- lining ducts of sweat glands

Question 26

stratified columnar epi structure and function

Answer 26

only a few layers and the apical layer is columnar + basal layer is cuboidal. male urethra, cornea, salivary ducts

Question 27

write a note on transitional epithelium

Answer 27

only in urinary system in linings of kidney, ureter,bladder and urethra .
basal cell layers are cuboidal where apical cell layers are dome shaped when relaxed. apical cells flatten- allow tissue to stretch