Epithelia Flashcards
Outline the functions of epithelia
Secretory, absorption, mechanical (protection)
What are the different types of shaped cells of epithelia?
Squamous (flat)
Cuboidal (square-like)
Columnar
What are the different types of stratification of epithelia?
Simple epithelium (simple, single layer)
Stratified epithelium (several layers)
Pseudostratified (appeance of layers, appear stratified but all reach BM)
Transitional (several layers, change shape)
What does basement membrane do for epithelia?
Anchor epithelium to connective tissue
What is BM in contact with?
Basolateral membrane
What synthesises BM (basal lamina)?
Epithelial cell
What does basement membrane contain?
GAGs and collagen proteins (laminins)
What are the functions of basement membrane (4)?
1) epithelial anchorage (structural integrity to epithelial layer - anchored by hemidesmosomes)
2) gives polarity to epithelial cells
3) regulation of cell growth, org and diff through cell surface receptor and ECM
4) Diffusion barrier
What anchors the BM to cells?
Hemidesmosomes (integrins in hemidesmosome, to laminins in BM )
What can and what can’t penetrate basement membrane, what’s the consequence?
Nerves can
Blood vessels can’t -nutrients reach epithelial cells by diffusion
What are 2 specialisations of epithelia?
Cilia and microvilli
Where are simple squamous epithelium found?
Bronchioles
Loop of Henle
Inside blood vessels
Serous membranes
Describe appearance of simple squamous epithelium, why?
Single layers of flat cells, nuclei appear as bumps as cells are flat
What are functions of simple squamous?
Diffusion, secretion, absorption and filtration
Where is simple columnar epithelium found?
Bronchioles
Intestine
Uterine tubes
Glands
Describe functions of simple columnar epithelium?
Bronchioles: move particles out of bronchioles
Uterine tube: move oocyte by ciliated cell
Intestine: absorption.
Describe structure of simple columnar cells?
May have cilia or microvilli
Where are simple cuboidal epithelium found?
Kidney tubules, terminal bronchioles, thyroid follicles
Describe structure of simple cuboidal epithelium?
Microvilli and cilia
What is the function of simple cuboidal epithelium?
Active transport, secretion, absorption