Epithelia

Question 1

What is epithelia

Answer 1

Comprise cohesive sheet of cells, with one or more layers, resting on a basement membrane

Think -lining

Question 2

Define simple epithelia

Answer 2

Single layer of cells on a basement membrane

Question 3

Define stratified (compound) epithelia

Answer 3

Two or more layers of cells on a basement membrane

Question 4

Define simple squamous epithelium

Answer 4

Single layer of flattened plate-like cells on a basement membrane

Often the nucleus will look like it stands proud

Parallel oval nuclei (1 per cell)

Question 5

What does simple squamous epithelium line

Answer 5

Blood vessels (endothelium)
Outside the lungs (mesothelium)
Abdominal organs (peritoneum)
Lung alveoli

Question 6

Define simple cuboidal epithelium

Answer 6

Single layer of cells with similar height and width on a basement membrane

Central spherical nuclei (1 per cell)

Question 7

What do simple cuboidal epithelium line

Answer 7

Kidney tubules
Small ducts e.g. salivary glands

Question 8

Define simple columnar epithelium

Answer 8

Single layer of cells taller than they are wide, on a basement membrane

Question 9

What do simple columnar epithelium line

Answer 9

Stomach
Intestines
Uterus

May or may not have cilia or microvilli

Question 10

Define microvilli

Answer 10

Microscopic projections on luminal surface of absorptive cells

Increase surface area
Intestinal brush border

Question 11

Where would you find microvilli and cilia

Answer 11

Columnar epithelium

Question 12

Give examples of where you would find cilia

Answer 12

Respiratory tract
Reproductive tract

Trachea
Fallopian tubes

Question 13

Define cilia

Answer 13

Microscopic projections on luminal surface of cells

Question 14

Define stratified epithelia

Answer 14

More than one layer of cells resting on the basement membrane

Protective function

Question 15

Where would you find stratified epithelia

Answer 15

Areas which are being continually worn down, worn away cells replaced from below

Found at sites subject to abrasive forces
e.g. skin, mouth (action of speaking, eating), oesophagus, vagina, cervix

Question 16

In stratified epithelia where do cells start

Answer 16

Resting on basement membrane - quite immature

As develop pushed up by new cells forming underneath them

Question 17

Define stratified squamous epithelium

Answer 17

Multiple layers of cells on basement membrane

Mature surface layers are plate like-squames

Question 18

Where would you find stratified squamous epithelium

Answer 18

Mouth
Oropharynx
Oesophagus
Vagina

Question 19

What are the two types of stratified squamous epithelium

Answer 19

Keratinised - skin
Non-keratinised

Question 20

What is the role of keratin

Answer 20

Waterproof epithelium

Wet sites of the body will not find keratin production

Question 21

Define pseudostratified epithelium

Answer 21

Single layer of cells of variable height

Mimicking multiple layers on basement membrane

All cells in contact with basement membrane

Question 22

Where would you find pseudostratified epithelium

Answer 22

Lines the conducting airways

Question 23

What is another name for pseudostratified ciliated epithelium

Answer 23

Respiratory epithelium

Question 24

Define urothelium

Answer 24

Specialised stratified epithelium

Breaks the rules -

Surface layer of umbrella cells

Cells between umbrella cells appear 3-7 layers thick and this layer is pseudostratified

Question 25

What is another name for urothelium

Answer 25

Transitional epithelium

Question 26

Where is urothelium found

Answer 26

Lines collecting part of the urinary tract - Bladder - Ureter - Renal pelvis

Question 27

What is the significance of the basement membrane

Answer 27

Always present Infer presence between difference in epithelium and underling tissue

Question 28

What stain would you use if you wanted to see the basement membrane

Answer 28

PAS - stains basement membrane magenta

Question 29

What is the basement membrane

Answer 29

Composed of several extra-cellular proteins including collagen IV and fibronectin Essential for the proper functioning and survival of the epithelium

Question 30

What is important for the proper functioning of the epithelium

Answer 30

Basement membrane and epithelial junctions

Question 31

What are epithelial junctions

Answer 31

Occluding (tight) junctions Band-like fusions between cells that are impervious to most molecules Prevent diffusion between cells

Question 32

What is the role of desmosomes in epithelial junctions

Answer 32

Anchoring/Adherent junctions Plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells Spread forces across several cells Prominent in the skin - places where abrasive

Question 33

What is the role of gap junctions

Answer 33

e.g. communicating junctions Electrical junctions that permit the transfer of small molecules Electrically couple adjacent cells

Question 34

Where are microvilli found

Answer 34

Absorptive epithelial cells e.g. gut and kidney tubules

Question 35

How many cilia are there per epithelial cell

Answer 35

300

Question 36

What do all epithelial have

Answer 36

Basement membrane