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Flashcards in Epithelia Deck (18)
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Define epithelia

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

1

Explain the position of the basement membrane

Between epithelia cells and connective tissue

2

Explain structure of the basement membrane

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

3

Explain the function of the basement membrane

Strong flexible layer for epithelial cells to adhere to
Cellular and molecular filter

4

Describe simple epithelia

One cell layer thick

5

Describe stratified/compound epithelia

More than one cell layer thick

6

Describe pseudostratified epithelia

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

7

Describe squamous epithelia

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

8

Describe cuboidal epithelia

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

9

Describe columnar epithelium

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

10

Describe transitional epithelium

Can stretch and distend e.g.bladder ureter urethra

11

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

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

12

What is metaplasia?

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

13

What is neoplasia

Change in epithelia results in tumour growth

14

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

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

15

Describe cillia

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

16

Describe micro villi

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

17

Describe stereo cillia

Elongated micro villi
Immobile
Found lining tubules of epidiymus