Lecture 29 - Chapter 16 - Endocrinology

Question 1

Anterior pituitary has six hormones that are peptide hormones. 5/6 hormones activate target cells via cAMP second-messenger system. What is that one hormone that doesn’t use cAMP?

Answer 1

Growth hormone is the one hormone that doesn’t activate the cAMP second-messenger system.

Question 2

4/6 hormones secreted by the anterior pituitary are tropic hormones (they regulate secretion of other hormones). What are the two hormones that ARE NOT tropic.

Answer 2

Growth hormone & Prolactin

Question 3

What is the function of growth hormone?

Answer 3

• Has direct actions on metabolism and indirect actions on growth-promoting actions.
• Produced by somatotropic cells

Question 4

How does growth hormone have direct actions on metabolism?

Answer 4

• Triggers liver to break down glycogen into glucose
• Increases blood levels of fatty acids for use as fuel, and encourages cellular protein synthesis

Question 5

How does growth hormone have indirect actions on metabolism?

Answer 5

• It stimulates most cells to enlarge and divide, but major targets are bone and skeletal muscle.

Question 6

What regulates the secretion of growth hormone?

Answer 6

Growth hormone-releasing hormone (GHRH) stimulates growth hormone release

Triggered by low blood growth hormone, low glucose, or high amino acid levels.

Question 7

What is the function of prolactin and what regulates its secretion?

Answer 7

• Prolactin stimulates milk production in females
• Its regulated by prolactin-inhibiting hormone, which is dopamine
• Increased estrogen levels stimulate Prolactin
• Sucking on breast stimulates Prolactin release

Question 8

What is the relationship between Thyroid-releasing Hormone (TRH) and Thyroid-stimulating hormone (TSH)?

Answer 8

• TRH is released by the hypothalamus and triggers the anterior pituitary to release TSH.
• TSH will cause the thyroid to release T3, T4, and calcitonin

Question 9

What regulates TSH?

Answer 9

• TSH is inhibited by rising blood levels of thyroid hormones that act on both pituitary and hypothalamus. Also inhibited by GHIH

Question 10

What is the function of Adrenocorticotropic hormone (ACTH)?

Also called corticotropin as it is secreted by corticotropic cells.

Answer 10

• ACTH stimulates the adrenal cortex to release corticosteroids
• ACTH is only released if corticotropin-releasing hormone (CRH) triggers the anterior pituitary to release it.

Question 11

How is ACTH regulated?

Answer 11

• CRH controls the amount of ACTH that gets released
• Fevers, hypoglycemia, and stressors determine how much CRH is released.

Hyopglycemia = low glucose in blood

Question 12

What are gonadotropins?

Answer 12

• FSH and LH
  1. FSH stimulates production of gametes (egg or sperm)
  2. LH promotes production of gonadal hormones (In males, stimulates production of testosterone. In females it triggers ovulation and release of estrogen)

Question 13

What regulates gonadotropins?

Answer 13

GnRH from the hypothalamus triggers the anterior pituitary to release gonadotropins.