Signalling between cells I

Question 1

What are the three types of signalling?

Answer 1

Autocrine
Paracrine
Endocrine

Question 2

What type of signalling is glucagon involved in?

Answer 2

Endocrine – it acts on liver cells promoting gluconeogenesis and glycogenolysis

Question 3

What type of signalling is insulin involved in?

Answer 3

Endocrine – inhibits gluconeogenesis and glycogenolysis in the liver
Paracrine – inhibits glucagon synthesis by nearby alpha cells

Question 4

Give an example of signalling between membrane attached proteins.

Answer 4

GP120 and CD4 between HIV and T lymphocyte

Question 5

Give an example of autocrine signalling.

Answer 5

Activated T lymphocytes have IL-2 receptors and secrete IL-2

Question 6

Describe the signalling that takes place at neuromuscular junctions.

Answer 6

The action potential propagates along the axon and the depolarisation causes the opening of VGCCs
Ca2+ influx
Vesicle exocytosis
Acetylcholine diffuses across the synaptic cleft and binds to sarcolemmal nicotinic receptors that lead to depolarisation of the postsynaptic membrane
Acetylcholine is broken down by cholinesterase and recycled

Question 7

What are the four types of Signal Receivers?

Answer 7

Ionotropic Receptors
G-protein linked receptors
Enzyme-linked receptors
Intracellular Receptors