Histology and Pathology of Epithelia

Question 1

What are the 5 types of cell junction superficial to deep?

Answer 1

Tight (occluding) junctions - form band, maintain polarity
Adherins junctions - actin–>cadherin
Desmosomes - intermediate–>cadherin
Gap junctions - 6 connexins, one connexon
Hemidesmosomes - intermediate–>integrins–>laminin

Question 2

What is the visible difference between euchromatic and heterochromatic nuclei? What does this indicate?

Answer 2

Euchromatic = no stainable, active DNA
Heterochromatic = stainable, inactive DNA
Indicates how much protein that cell is making

Question 3

What are the 6 types of epithelia?

Where are they found?

Answer 3

Simple columnar - small intestine
Simple cuboidal - collecting tubes
Simple squamous - lining of vessels
Stratified - epidermis/oesphagus
Pseudostratified - respiratory epithelium 
Transitional - bladder

Question 4

What structure does respiratory epithelium have and why?

Answer 4

Pseudostratified to accomodate goblet cells

Question 5

What is the specialised function of transitional epithelia

Answer 5

Folded, umbrella cells

Allows distention

Question 6

Why is polarity in simple cuboidal and columnar epithelia important?

Answer 6

Only want certain proteins on particular surfaces e.g. cilia and microvilli on apical surface