Epithelia

Question 0

Explain the position of the basement membrane

Answer 0

Between epithelia cells and connective tissue

Question 1

Define epithelia

Answer 1

Sheets of contiguous cells, of varied embryonic origin that cover the external surfaces of the body and line internal surfaces

Question 2

Explain structure of the basement membrane

Answer 2

Basal lamina laid down by epithelial cells closest, thickness varied by changing layer of reticular fibres

Question 3

Explain the function of the basement membrane

Answer 3

Strong flexible layer for epithelial cells to adhere to

Cellular and molecular filter

Question 4

Describe simple epithelia

Answer 4

One cell layer thick

Question 5

Describe stratified/compound epithelia

Answer 5

More than one cell layer thick

Question 6

Describe pseudostratified epithelia

Answer 6

Single layer but appears layered
E.g. URT - secretion and conduit
Epididymis - absorption

Question 7

Describe squamous epithelia

Answer 7

Flat, scale like can be keratinised for extra protection
Pericardium,peritoneum - lubrication
Alveoli - gas exchange
Bowmans capsule - barrier
Endothelium - at via pinocytes

Question 8

Describe cuboidal epithelia

Answer 8

Cube shaped
Exocrine glands - absorption and conduit
Kidney tubules - absorption and secretion
Ovary - barrier
Thyroid - hormone synthesis and storage

Question 9

Describe columnar epithelium

Answer 9

Rectangle
Small intestine and colon - absorption 
Stomach lining, colon - secretion
Small intestine , colon - lubrication
Oviduct - transport

Question 10

Describe transitional epithelium

Answer 10

Can stretch and distend e.g.bladder ureter urethra

Question 11

Why does epidermal epithelia have a longer renewal rate than epithelia of the small intestine?

Answer 11

Depends on function, 28 days in dermis as migration, keratinisation, death and sloughing take a while, only 4-6 in small intestine as constantly processing food

Question 12

What is metaplasia?

Answer 12

Change of one type of epithelium to another, in heavy smokers pseudostratified Collumnar goes to stratified squamous for more protection

Question 13

What is neoplasia

Answer 13

Change in epithelia results in tumour growth

Question 14

Why are only basal layer of cells in contact with the basement membrane?

Answer 14

Basement membrane separates epithelium from underlying connective tissue, layers of epithelium rest upon it

Question 15

Describe cillia

Answer 15

Projections of plasma membrane
Core of micro tubules in 9+2 arrangement
Can beat in synchronicity to move material across cell surface

Question 16

Describe micro villi

Answer 16

Brush borders
Sites to increase cell surface area (for absorption?)
Shape maintained by internal actin filaments

Question 17

Describe stereo cillia

Answer 17

Elongated micro villi
Immobile
Found lining tubules of epidiymus