Epithelial Tissues

Question 1

Describe the differences between squamous, cuboidal and columnar cells.

Answer 1

Squamous are wider than they are tall (plate shaped)
Cuboidal are as wide as they are long
Columnar are taller than they are wide

Question 2

What are the two types of layering you find in epithelia?

Answer 2

Simple – one layer

Stratified – several layers

Question 3

What is the difference between keratinising and non-keratinising squamous epithelia?

Answer 3

Keratinising – nuclei are not visible in the surface cells

Non-keratinising – nuclei are visible in the surface cells

Question 4

Give one example of where you would find: simple squamous, simple cuboidal, simple columnar, stratified squamous (keratinising and non-keratinising) and pseudostratified columnar epithelia.

Answer 4

Simple Squamous – endothelial cells, lung alveolar
Simple cuboidal – kidney collecting duct
Simple columnar – enterocytes
Keratinising Stratified Squamous – skin
Non-Keratinising Stratified Squamous – oesophagus
Pseudostratified columnar – upper airways

Question 5

What is the key player in establishing epithelial polarity?

Answer 5

Tight Junctions

Question 6

How do they establish epithelial polarity?

Answer 6

They block the paracellular pathways so molecules that want to pass across the epithelia must pass through the cells

Question 7

Why is it necessary for epithelial cells to have polarity?

Answer 7

Many processes (e.g. secretion, absorption) are unidirectional

Question 8

Describe cell division in the villus

Answer 8

There are intestinal stem cells in the crypt. New cells are shunted up the villus as other new cells form. Cells are lost from the tip.

Question 9

What type of epithelia usually constitutes protective epithelia?

Answer 9

Keratinising and Non-keratinising stratified squamous

Question 10

What is Epidermolysis bullosa an example of?

Answer 10

Disorder of cytokeratin and desmosomes