Hypothalamic-Pituitary Relationships and Biofeedback Part 1 (Creamer)

Question 1

What is the physical connection between the hypothalamus and the pituitary gland?

Answer 1

Hypophysial stalk

Question 2

If there are tumors in the pituitary area, what symptoms can it cause?

Answer 2

Due to its proximity, the pituitary gland can put pressure to the optic nerves and can cause visual problems and dizziness.

Question 3

What are the nucleus in the hypothalamus that send axons to the posterior pituitary

Answer 3

Supraoptic nucleus (SON)

Paraventricular nucleus (PVN)

Question 4

What do the paraventricular nucleus and supraoptic nucleus produce and secrete to the hypothalamus?

Answer 4

Oxytocin & ADH (Vasopressin)

Question 5

What does the anterior pituitary secrete (6 tropic hormones)?

Answer 5

ACTH

TSH

FSH

LH

GH

Prolactin

Question 6

How is the anterior pituitary connected to the hypothalamus

Answer 6

Hypothalamic-hypohysial portal blood vessels

Question 7

The connections between the hypothalamus and posterior lobe are ____?

Answer 7

neural

Question 8

The connections between the hypothalamus and anterior lobe are ____?

Answer 8

neural and hormonal

Question 9

What hormone is a negative inhibitor of growth hormone?

Answer 9

Somatostatin (GHIH)

IGF-1

Question 10

What is a primary endocrine disorder?

Answer 10

Defect in peripheral endocrine gland that can cause low or high levels of hormones

Question 11

What is a secondary endocrine disorder?

Answer 11

Defect in pituitary gland that can cause low or high levels of hormones

Question 12

What is a tertiary endocrine disorder?

Answer 12

Defect in hypothalamus that can cause low or high levels of hormones

Question 13

In the HPG axis, what is the major hypothalamic hormone

Answer 13

GnRH

Question 14

In the HPG axis, what is major pituitary hormone?

Answer 14

FSH and LH

Question 15

In the HPG axis, what is the peripheral target organ for males?

Answer 15

Testes

LH targets Leydig cells

FSH targets Sertoli cells

Question 16

How is the HPG axis in males controlled?

Answer 16

Testosterone from Leydig cells inhibits GnRH and LH

Inhibin from the Sertoli cells inhibits FSH

Question 17

In the HPG axis, what is the peripheral target organ for females?

Answer 17

Ovaries

LH targets Theca cells

FSH targets Granulosa cells

Question 18

How is the HPG axis in females controlled?

Answer 18

Progestins and estrogen from granulosa cells inhibit GnRH, LH & FSH.

Also, inhibin from granulosa cells inhibits FSH & LH during ovulation.

Question 19

What happens if GnRH release is inhibited?

Answer 19

Reduce production of gametes and affect fertility

Question 20

What causes acromegaly?

Answer 20

Prolonged and excessive secretion of growth hormone in adult life

Question 21

What are symptoms of acromegaly?

Answer 21

Large hands, feet, and head

Prominent lower jaw

Cardiomegaly

Organomegaly

Hypertension

Question 22

What regulates the release of growth hormone

Answer 22

Growth hormone release hormone (GHRH) & Growth hormone inhibiting hormone (GHIH) = somatostain. Both released from hypothalmus

Question 23

What is another name for GH

Answer 23

Somatotropin

Question 24

Explain the direct and indirect targets of GH

Answer 24

Direct: Targets bone and muscle

Indirect: Targets liver which then secrets IGF-1 which can target almost every cell type in body (PRIMARY METHOD)

Question 25

What can stimulate release of growth hormone?

Answer 25

Fasting/hunger/starvation Hypoglycemia Puberty Exercise Sleep Stress

Question 26

What does growth hormone induce?

Answer 26

Growth Cell Reproduction Metabolism

Question 27

How does the liver induce a negative feedback on the hypothalamus and pituitary gland?

Answer 27

Insulin-like growth factor 1 (IGF-1) inhibits GHRH (hypothalamus) & GH (AP) but stimulates GHIH

Question 28

If there is an excess of growth hormone noticed before the closure of the bone epiphyses due to IGF-1, what do you expect to see?

Answer 28

Gigantism

Question 29

If there is an excess of growth hormone noticed after the closure of the bone epiphyses, what do you expect to see?

Answer 29

Acromegaly

Question 30

What happens when an individual has adequate carbohydrate and protein intake?

Answer 30

IGF-1 is produced leading to mitogenesis, lipolysis, and differentiation

Question 31

What happens when an individual has adequate carbohydrate intake but not enough protein intake?

Answer 31

GH production is inhibited due to inadequate amino acid availability so liver will not produce IGF-1 leading to lipogenesis and carbohydrate storage (weight gain)

Question 32

What happens when an individual has adequate protein intake but not enough carbohydrate intake?

Answer 32

Increased GH levels so liver will produce IGF-1 leading to lipolysis, ketogenic metabolism and diabetogenic effects *Shift in metabolism, by usig lipids as an energy source*

Question 33

How does GH promote insulin insensitivity

Answer 33

A shift in using lipids as an energy source leads to a decrease in glucose uptake by cells.

Question 34

What are the metabolic functions of growth hormone?

Answer 34

* Diabetogenic effect: increase of blood glucose and insulin levels * Increase in protein synthesis and organ growth * Increase in linear growth: stimulates DNA, RNA, and protein synthesis

Question 35

During which parts of the day does GH secretion peak?

Answer 35

Exercise Beginning of sleep

Question 36

Why do we give an oral glucose tolerance test to someone suspected to have acromegaly?

Answer 36

Glucose typically shuts down secretion of GH. We can give glucose to patients suspected of acromegaly to see if blood GH levels will decrease. If they don't decrease, patient might have acromegaly.

Question 37

Why do we look at IGF-I levels when suspecting a diagnosis of acromegaly?

Answer 37

IGF-1 levels remain constant during the day while GH levels fluctuate.

Question 38

How does the regulation of prolactin secretion differ from the other AP hormones

Answer 38

Prolactin is regulated through negative inhibition by dopamine. *Dopamine suppresses it's release*

Question 39

What is the negative feedback activity of prolactin

Answer 39

Inhibits GnRH (LH and FSH) release which decrease reproductive function and suppresses sexual drive (This is a good thing right after a pregnancy)

Question 40

What is the main inhibitor of prolactin secretion?

Answer 40

Dopamine

Question 41

Describe the production and release of oxytocin from the posterior pituitary

Answer 41

1. Produced in the hypothalamus as prepro-oxyphysin 2. Cleaved and transported to posterior pituitary in vesicles where it is stored in it's active form 3. Released as oxytocin

Question 42

What are the actions of oxytocin?

Answer 42

Milk ejection Uterine contractions (postitive feedback)