3. Hypothalmic-Pituitary Relationships

Question 1

What 2 things are secreted by the majority of the cell bodies in the supraoptic nuclei?

Answer 1

Antidiuretic hormone (ADH).

Neurophysin II.

Question 2

What is the elementary precursor for oxytocin?

What is the elementary precursor for ADH?

Answer 2

Preprooxyphysin.

Prepropressophysin.

Question 3

Recall the pathway for GH regulation and check it against the pathway on the reverse.

Answer 3

Question 4

What is more important for the regulation of ADH, blood volume or osmolarity?

Answer 4

Osmolarity. Only a 1% change is required to cause an effect, whereas a 10% change in blood volume is necessary.

Question 5

What is released by a lactotroph?

What hypothalamic hormone triggers its release?

Answer 5

Prolactin.

TRH.

Question 6

How does growth hormone promote growth?

What specific cell type is responsible for growth hormone’s effect on bones?

Answer 6

Increases protein synthesis (organ growth).

Increases uptake of amino acids.

Stimulates synthesis of DNA, RNA, and new proteins.

Increases metabolism in and proliferation of chondrocytes.

Chondrocytes are responsible for growth hormone’s effect on bones.

Question 7

What cell population does corticotropin-releasing hormone act upon?

What hormone is ultimately released as a result?

Answer 7

Corticotrophs.

ACTH

Question 8

How might damage to the pituitary gland cause diabetes insipidus?

Answer 8

Damage to the cells which release antidiuretic hormone.

Question 9

What are the diabetogenic effects of growth hormone?

Answer 9

Causes insulin resistance.

Decreases tissue glucose uptake and utilization.

Increases lipolysis and adipose tissue.

Results in increased blood insulin levels (which causes the insulin resistance).

Question 10

What are the three families of anterior pituitary hormones?

Answer 10

The ACTH family.

The FSH, LH, and TSH (FLaT) family.

Prolactin and GH family.

Question 11

What molecule mediates growth hormone’s growth effects?

Answer 11

Somatomedins.

Question 12

What cells of the hypothalamus produce the most oxytocin?

Answer 12

Cells of the paraventricular nucleus.

Question 13

What is affected in a primary / secondary / tertiary endocrine disorder respectively?

Answer 13

Primary disorder: peripheral endocrine gland defect.

Secondary disorder: pituitary gland defect.

Tertiary disorder: hypothalamus defect

Question 14

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

Answer 14

Because growth hormone leads to the secretion of IGF-I, which should then inhibit growth hormone secretion. If both growth hormone secretion and IGF-I secretion are high, something else is stimulating growth hormone secretion.

Also, growth hormone levels can fluctuate throughout the day, whereas IGF-I levels remain constant.

Question 15

Which of the anterior pituitary hormones have an α/β subunit?

Answer 15

The FLaT family:

follicle stimulating hormone, luteinizing hormone, and thyroid stimulating hormone.

Question 16

What would we expect to see (increase or decrease) in the levels of growth hormone, somatomedin, and insulin during periods of fasting?

Answer 16

Growth hormone increases.

Somatomedin decreases (to decrease the growth effects of growth hormone).

Insulin decreases.

Question 17

What pathologies can cause a growth hormone deficiency?

Answer 17

Decreased secretion of growth hormone releasing hormone (hypothalmic dysfunction).

Decreased growth hormone secretion.

Failure to generate somatomedins.

Growth hormone or somatomedin resistance (deficiency of receptors).

Question 18

How might damage to the anterior pituitary cause loss of pigmentation?

Answer 18

Damage to ACTH secreting cells (corticotropic cells) can cause lack of pigmentation due to a loss of melanocyte stimulating hormone (MSH)

Question 19

What cell type is the most significant in the anterior lobe of the pituitary?

Answer 19

The somatotroph population.

Question 20

What does somatostatin do to the pituitary gland?

Answer 20

Inhibits somatotrophs from producing growth hormone.

Question 21

What is the effect of damage to growth hormone secreting cells of the anterior pituitary in adults?

Answer 21

No effect.

Question 22

How do hypothalmic hormones not appear in the systemic circulation in high concentration?

Answer 22

Because they pass via the hypothalmic-hypophyseal portal vessels into the pituitary gland and are mostly absorbed there before they return to circulation.

Question 23

Prolactin inhibitory factor from the hypothalamus (also called what?) affects what cell population?

What is inhibited as a result?

Answer 23

Prolactin inhibitory factor (dopamine) inhibits lactotrophs from releasing prolactin.

Question 24

Why might most pituitary adenomas (which are associated with FSH and or LH) be nonfunctional?

Answer 24

Because they secrete either the α subunit or the β subunit but not both.

Question 25

What cells of the hypothalamus secrete the most ADH?

Answer 25

Cells of the supraoptic nucleus.

Question 26

What is Sheehan syndrome?

What are the primary symptoms?

Answer 26

Postpartum hypopituitarism due to necrosis of the pituitary gland.

Agalactorrhea/difficulties in lactation, amenorrhea, hypothyroidism, other endocrine dysfunction might also be present.

Question 27

The release of what hormones are primarily stimulated by ACTH?

Answer 27

Cortisol.

Sex hormones (androgens).

Question 28

What 2 things are secreted by the majority of the cell bodies of the paraventricular nuclei of the posterior pituitary?

Answer 28

Oxytocin.

Neurophysin I.

Question 29

What stimulatory hormone from the hypothalamus increases secretion of prolactin?

Answer 29

Thyrotropin releasing hormone.