Question

Verify the series of steps that lead to an increase in plasma cortisol levels, beginning with the release of CRH:

a) Exocytosis of vesicles that contain CRH --> Binding of CRH to cortisol receptors --> Release of cortisol into bloodstream --> Inhibition of CRH production

b) Release of CRH into bloodstream --> Binding of CRH to cortisol receptors --> Exocytosis of vesicles containing cortisol --> Inhibition of CRH production

c) Exocytosis of vesicles containing cortisol --> Binding of cortisol to CRH receptors --> Release of CRH into bloodstream --> Inhibition of CRH production

d) Release of cortisol into bloodstream --> Binding of cortisol to CRH receptors --> Exocytosis of vesicles containing CRH --> Inhibition of CRH production

Answer 1

The accurate sequence of hormonal release begins with CRH from the hypothalamus, leading to ACTH release from the anterior pituitary, which triggers cortisol release from the adrenal cortex, and subsequently negative feedback inhibits CRH and ACTH production.

Step-by-step explanation:

The correct sequence of steps leading to an increase in plasma cortisol levels starting with the release of CRH is none of the options provided in the question, as they contain inaccuracies in describing the hormone cascade.

The accurate sequence is as follows:

1. Release of CRH into the bloodstream from the hypothalamus.
2. CRH binds to receptors on the anterior pituitary, leading to the release of ACTH.
3. ACTH then stimulates the adrenal cortex to perform exocytosis of vesicles containing cortisol.
4. Cortisol is released into the bloodstream.
5. Elevated cortisol levels then provide negative feedback to inhibit further CRH and ACTH production.

This process is part of the hypothalamic-pituitary-adrenal (HPA) axis and its response to stress. Cortisol is a glucocorticoid that affects various bodily processes and is involved in the body's stress response.