Epithelium

Question 1

What are the 4 basic tissue types

Answer 1

Epithelial
Connective
Muscle
Nerve

Question 2

General epithelial functions

Answer 2

Protection
Secretion
Absorption
Dialysis
Sensation

Question 3

What are the 2 ways to classify epithelium

Answer 3

1. Number of layers
2. Shape of top layer
   - squamous
   - cuboidal
   - columnar

Question 4

Single layer of epithelium is called

Answer 4

Simple

Question 5

Multiple layers of epithelium are called

Answer 5

Stratified

Question 6

Define squamous

Answer 6

Cell that is wider than height

Question 7

Define cuboidal

Answer 7

Cuboid shaped

Height and width similar

Question 8

Define columnar

Answer 8

Height larger than width

Question 9

What are the 2 varieties of stratified squamous epithelium

Answer 9

1. Keratinised

2. Non keratinised

Question 10

Describe keratinised stratified squamous epithelium

Answer 10

As cells get towards top they fill up with protein molecules containing keratin and ‘waxy stuff’= cant survive so break down e.g. skin
New cells made by stem cells to replace the dead keratinised ones

Question 11

Described non keratinised stratified squamous epithelial cells

Answer 11

Don’t have keratinised layer e.g.most internal surfaces
Cells still have nuclei
Kept moist by glandular secretions

Question 12

Epithelial that dont fit into classification system

Answer 12

Pseudo stratified
- no clear defined layers
- different shapes of cells within the same layer
May be because their life expectancy is short yet they need a complete layer so replacement grow through whilst those cells are still present

Question 13

Transitional epithelium

Answer 13

The cells changing shape e.g. bladder shifts between stretched and collapsed cells as it empties and fills

Question 14

Features common to all epithelia

Answer 14

1. Cellular it’s
   - separate internal and external enviro and cellular monitoring of transfer
2. Specialised intercellular junctions
   -desmosomes and adherens junctions
   -Tight junctions press cells together so there’s no gaps
   = coordinated behaviour
3. Polarity
   - top contacts external
   - bottom contacts basement membrane and body
   - laterally attached to other cells

Question 15

Describe basement membrane structure

Answer 15

-basal lamina = made from epithelium
- reticular fibres (collagen) = made from connective tissue
They fit together to attach epithelia to organs

Question 16

Stratified epithelial cell functions

Answer 16

• protect tissues from damage
• tough type = stratified squamous keratinised
• waterproof covering

Question 17

Simple epithelial cell functions (columnar and cuboidal)

Answer 17

Occur when substances must be transported
Is thin and flat so acts as a filter (lets water and ions through but holds back large mols)

Columnar and cuboidal
- role in active transport and modification of materials
Plenty of mitochondria, lysosomes and golgi

Question 18

Epithelia

Answer 18

Lining all body surfaces
A vascular = no blood vessels
Controls material entry and exit
Can create structures e.g. glands