Epithelial Flashcards
(41 cards)
What are epithelia?
Cells that line/cover all the body surfaces, tubes and cavities
What connects epithelial cells together?
Tight junctions
What separates the epithelium from the underlying tissues?
Basement membrane
What 2 layers form the basement membrane?
Basil lamena, connective tissue (collagen and other protein fibres)
Why do epithelia have to undergo rapid division?
Cells are continually lost from the surface so new cells are needed to replace them
What are tumours that develop from epithelia called?
Carcinomas
Name the 3 types of epithelia
- Columnar
- Cuboidal
- Squamous
2 types of classification by no. Of layers of cells-
- Simple
2. Stratified
What type of epithelia is found where diffusion, absorption or secretion takes place (simple or stratified)
Simple
Where is stratified epithelia found?
Where there is a need for protection
Eg skin, lining urethra, respiratory tract
Where do u find transitional epithelia?
Bladder
Where do u find stratified cuboidal?
Reproductive system eg lining urethra
What type of epithelia found in blood vessels and why?
Simple squamous- short diffusion pathway for exchange of chemicals
What are the basal cells in stratified epithelia?
Cells in contact with basal lamena
Cells in contact with lumen in stratified epithelia
Apical
What type of epithelia is found in skin
Stratified squamous
Why simple squamous good for exchange?
Pores between cells allow easy passage of molecules
Why cuboidal/ columnar good for transport through?
Tight junctions limit movement between cells so not good for exchange. But these cells have more organelles eg ribosomes and rer to produce transport proteins and mitochondria for atp for at.
Cilia vs microvilli
Cilia have wave like movements which allow them to move substances along whereas microvilli don’t move, they just increase SA of cell membrane
5 functions of epithelia
Protective, secretory, ciliated, transport, exchange
What does the mesothelium line?
Pleura, pericardium and peritoneum. Has a secretory role- secretes a watery fluid that lubricates and prevents walls stickjnv
Role of epithelia in small intestine and what type
Simple columnar
Increase SA for absorption (microvilli on apical surface and basal invaginations)
Mucus secretion to lubricate gut contents- goblet cells
How to increase SA of small intestine
Large folds of wall, villi, microvilli
What type of cells secrete mucus into linen of small intestine ?
Goblet
