FoM:L1 - Epithelia

Question 1

What is epithelial tissue?

Answer 1

thin continuous sheet of cells

Question 2

What is glandular epithelium?

Answer 2

• formed by downgrowth of epithelium into underlying tissues
• can form secretory glands and ducts

Question 3

What are the 3 functions of epithelial tissues?

Answer 3

• protection
• barrier between internal and external environment
• allows transport of materials (diffusion, absorption and secretion)

Question 4

What are 5 characteristics of surface epithelium?

Answer 4

• basal surface of cells rests on basement membrane
• polarity (apical, basal and lateral surfaces)
• Contiguous adhesive (cells joined by intercellular junctions)
• No direct blood supply (diffusion important!)
• High mitotic activity

Question 5

What is the basement membrane?

Answer 5

thin protein later that lies deep in epithelium, made up of 3 parts

Question 6

What is the function of the BM? (3 points)

Answer 6

• support and anchor epithelium to tissue
• physical and selective diffusion barrier
• essential for epithelial cell proliferation ansd polarisation

Question 7

Where are junctions of epithelial cells located?

Answer 7

basal - BM
lateral - other cells
gap junctions allow communication

Question 8

What are the 3 types of apical specialisations?

Answer 8

Microvilli - increase SA for absorption; made of actin and immobile
Cilia - waft and move things; made of microtubules (9,2) so are mobile
Stereocilia - increase SA for absorption; made of actin and immobile, slightly longer than MV

Question 9

Where are each of the apical specialisations found? (examples of each)

Answer 9

Microvilli - intestinal epithelium
Cilia - respiratory and uterine tube epithelia
Stereocilia - epididymis and vas deferens

Question 10

What 2 structural features are used to classify surface epithelium?

Answer 10

• Thickness: simple vs stratified
• Shape: squamous vs cuboidal vs columnar

Question 11

Give an overview of simple squamous cells

Answer 11

function: barrier, trans-epithelial transport
Location: endothelium (vessels), respiratory air spaces; mesothelium (covers organs)

Question 12

Give an overview of simple cuboidal cells

Answer 12

Function: barrier; absorption and secretion
Location: kidney tubules, bronchioles, secretary cells of some glands

Question 13

Give an overview of simple columnar cells

Answer 13

Function: barrier; absorption and secretion
Location: lines GI tract, uterus

Question 14

Give an overview of stratified squamous cells

Answer 14

Function: protective barrier against wear + tear
Location: skin, lining of oral cavity, oesophagus, vagina

Question 15

Give an overview of stratified cuboidal/columnar cells

Answer 15

Function: barrier; some secretory/absorptive function
Location: ducts of sweat glands, walls of large ducts

Question 16

What are pseudo-stratified columnar epithelial cells?

Answer 16

• SIMPLE COLUMNAR epithelium
• appears stratified
• all cells rest on BM
• eg respiratory epithelium

Question 17

What are transitional epithelium?

Answer 17

• stratified
• only lines lumens of UT
• Change appearance depending on stretch
• relaxed: surface umbrella cells, look rounded
• stretched - thin, squamous like cells

Question 18

What are the types of gland?

Answer 18

exocrine: link with surface, usually by a duct
endocrine: no connection with surface (no duct) secretions released into tissues

Question 19

How do exo and endocrine glands secrete?

Answer 19

Exo:
- merocrine; from apical cell surface
- Apocrine; partial loss of apical parts of cells
- Holocrine: entire cell
Endo:
from base of cell

Question 20

How can glands be classified by secretion?

Answer 20

mucous: glycoproteins and water
Serous: protein and water
Mixed: Both

Question 21

What is the only unicellular secretory portion?

Answer 21

goblet cells - not grown deeper into tissue
- use stain for secretions to identofy