Exam

Question 1

Explain the feedback regulation of the secretion of ATCH

Answer 1

Stress stimulates the hypothalamus, which releases Corticotropin-releasing hormone (CRH), which in turn stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary.

Then ACTH stimulates the adrenal cortex to release cortisol. Cortisol then initiates a series of metabolic effects that relieves the stressful state.

A direct negative feedback mechanism of cortisol inhibits both the hypothalamus and anterior pituitary gland, decreasing the release and concentration of cortisol.

Question 2

What are features of chemically gated ion channels?

Answer 2

Chemically gated ion channels open and close in response to binding of a specific ligand (e.g. a neurotransmitter) to the protein’s surface

Question 3

What are the features of a voltage gated ion channel?

Answer 3

A voltage gated ion channel opens and closes in response to changes in the membrane potential

Question 4

Where would you find a chemically gated ion channel?

Answer 4

In the postsynaptic neurone

Question 5

Where would you find a voltage gated ion channel?

Answer 5

In the axon

Question 6

Give an example of a voltage gated ion channel

Answer 6

Voltage gated K+ channels

Question 7

Give an example of a chemically gated ion channel?

Answer 7

Nicotinic acetylcholine receptor

Question 8

Outline the role of the nicotinic acetylcholine receptor

Answer 8

Nicotinic acetylcholine (ACh) receptors are responsible for transmission of nerve impulses from motor nerves to muscle fibres (muscle types) and for synaptic transmission in autonomic ganglia (neuronal types).

Question 9

Outline the role of a voltage gated potassium channel

Answer 9

During an action potential, the K+ channels open, allowing potassium to exit the cell, returning the neuronal membrane to it’s resting potential.