Endocrine - Hypothalamus & Pituitary Flashcards Preview

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Flashcards in Endocrine - Hypothalamus & Pituitary Deck (28)
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1

What 2 hormones are released by the posterior pituitary?

1. vasopressin (ADH, antidiuretic hormone)
2. oxytocin

2

Why is vasopressin released?

to conserve body water and regulate osmotic pressure of body fluids

3

How does the body know to release vasopressin?

dehydration leads to an increase in osmolarity which activates osmoreceptors in the brain and vasopressin secretion

4

What is the target organ of vasopressin?

kidney cells, specifically distal convoluted tubule and collecting ducts via cell surface receptors and cAMP formation; enhances water permeability and reabsorption

5

what happens when you are deficient in ADH?

central diabetes insipidus - inability to retain water, excess thirst, frequent urination

6

What drug can you use to treat deficient ADH?

1. clofibrate - increase ADH secretion
2. chlorpropamide - increase kidney response to ADH
3. diuretics

7

what happens when there is an excess of ADH?

- water retention
- headache
- drowsiness
- nausea

8

what drugs can you use to treat Excess ADH?

1. Butorphanol - decrease ADH secretion
2. demechlocycline - reduce kidney response to ADH

9

What does oxytocin do?

- stimulates the contraction of smooth muscle cells: mammary glands and uterus.
- suckling reflex when nursing stimulates oxytocin release
- released during labour to stimulate rhythmic uterine contractions

10

The release of growth hormone is stimulated by

- GHRH
- hypoglycemia
- exercise
- certain amino acids
- sleep

11

the release of growth hormone is inhibited by

- somatostatin
- IGF-1 (-ve feedback)
- hyperglycemia

12

What are the effects of growth hormone?

- stimulates release of IGF-1 from the liver and increases lipolysis, protein sun these and epiphyseal (bone) growth
- also decreases insulin sensitivity and decreases glucose uptake

13

what conditions could occur when there is a somatotrope tumor that causes an excess of GH?

1. gigantism (early in life)
2. acromegaly (GH excess after body has stopped growing)

14

what are ways to treat conditions caused by increased/excess GH?

1. tumor removal
2. SS analogs
3. GH receptor antagonist

15

laron dwarfism

abnormal Gh receptors that are unresponsive to hormone. Symptoms resemble those of severe GH deficiency even though GH levels in the blood are high

16

what can cause deficiency in GH?

- GHRH deficiency
- pituitary lesions (tumor, infection, defects)

17

what does release of prolactin do?

- promotes growth & function of mammary gland-milk production
- increased maternal behaviour
- inhibits gonadotropin secretion

18

how is prolactin controlled?

inhibited by hypothalamic dopamine

19

what stimulates prolactin release?

- oxytocin
- TRH
- VIP
- estrogen

20

the suckling reflex stimulates what?

- release of oxytocin from the posterior pituitary
- decrease of dopamine in hypothalamus resulting in prolactin release from anterior pituitary

21

galactorhhea

inappropriate milk production due to excess prolactin release

22

what can cause excess prolactin release ?

1. stress
2. dopamine receptor blockers (from psychiatric medications)
3. hyperprolactinemia- caused by adenomas and lactotropes

23

what happens in males when there is an excess of prolactin?

- impotence
- decreased sperm count
- infertility

24

how can excess prolactin release be treated?

dopamine agonists which suppress prolactin secretion and shrink prolactinomas

25

what is the action of LH?

stimulates estrogen, progesterone and testosterone

26

What is the action of FSH?

stimulates ovarian follicles and sperms

27

what hormones stimulate FSH and LH release?

- GnRH
- estrogen (high level)

28

what hormones inhibit FSH and LH release?

- inhibin (from gonads)
- estrogen (low level)
- progesterone
- testosterone