Cell Interactions In tissues

Question 0

Which cells secrete the majority of extracellular matrix?

Answer 0

Fibroblasts.

Question 1

What is the extracellular matrix?

Answer 1

It is composed of proteins and polysaccharides that are secreted by cells and assembled into an organised meshwork external to the cells.

Question 2

What is the most abundant extracellular protein in animal tissues?

Answer 2

Collagen.

Question 3

Give an example of circumstances where close contact between adjacent cells is important.

Answer 3

In epithelial tissues lining the gut wall, or in the skin.

Question 4

List the four main type of cell to cell junctions.

Answer 4

1) gap junctions
2) tight junctions
3) adherens junctions
4) anchoring junctions

Question 5

Briefly describe gap junctions (between cells).

Answer 5

A specialised type of cell junction which allows intercellular communications.

In smooth muscle of the intestine which must contract in a coordinated manner for peristalsis to occur gap junctions allow the transmission of molecules and electrical signals.

Question 6

Briefly describe tight junctions (between cells).

Answer 6

They link cells very closely forming a barrier which prevents the movement of molecules or ions between cells. They also prevent the movement of integral membrane proteins. This is useful for maintaining cell polarity, for example in epithelial cells in the gut.

Question 7

Briefly describe adherens junction.

Answer 7

Link the actin cytoskeleton of adjacent cells together (microfilaments)

Question 8

Briefly describe anchoring junctions.

Answer 8

Desmosomes: link adjacent cells together.
Hemidesmosomes: link cells to the extracellular matrix.

Use intermediate filaments.