Lecture #1 -- Hypothalamus and Pituitary Flashcards Preview

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Flashcards in Lecture #1 -- Hypothalamus and Pituitary Deck (67):
1

Dominant portion of the endocrine system?

Hypothalamus-pituitary

2

What glands are regulated by hypoth.-pit

Thyroid
Adrenal
Reproductive Glands
Somatic Growth, Lactation, Water Metabolism

3

Which Pit is neural?

Pos. Pit

4

What is the median eminence?

Upper portion of the neural stalk extending into the hypothalamus

5

Which Pit is not neural

A Pit

6

What connects the hypothalamus to the A Pit

Superior Hypophyseal Artery

7

What six peptides come from A Pit?

Prolactin, GH, TSH, ACTH, FSH, LH

8

Difference between a Long Feedback Loop, Fast feedback loop, and a short feedback loop

Short -- A Pit-->Hypo
Fast -- Ultimate Hormone --> A Pit, Hypo
Long -- Ultim. Hor --> A Pit, Hypo, CNS

9

What type of Hor travels btw Hypo and A Pot

Releasing or Inhibiting Factors

10

Name the Hypothalamic releasing hormones that stimulate secretion.

CRH, TRH, GHRH, GnRH, PRH

11

Name the Hypothalamic releasing hormones that inhibit secretion.

Somatostatin
Prolactin Inhibiting Hormone (Dopamine)

12

Describe hypothalamic releasing hormone release

Secretion in Pulses

13

Effects of stimulatory releasing hormones?

Act on mem receptors to stimulate the release of stored pituitary hormones
Stim synthesis of pit hormones
Stim hyperplasia/hypertrophy of target cells

14

Unique regulatory activity of releasing hormones?

They regulate their own receptors

15

Who generates ACTH? What is the hormone target?

Corticotrophs
Adrenal gland, Adipocytes, Melanocytes

16

Who generates TSH? What is the hormone target?

Thyrotrophs
Thyroid Gland

17

Who generates LH, FSH? What is the hormone target?

Gonadotroph
Gonads

18

Who generates GH? What is the hormone target?

Somatotrophs
All Tissues, Liver

19

Who generates PRL? What is the hormone target?

Lactotrophs
Breasts, Gonads

20

Cell type with the first, second and third highest presence in the A Pit

1. Somatotroph (40-50%)
2. Corticotroph (15-20%)
3. Gonadotroph/Lactotroph (10-15% each)

21

High levels of thyroid hormone can inhibit...

Anterior Pituitary secretions of TSH

22

Why have feedback?

Restoration of homeostasis

23

What converts GH to somatomedins?
What do somatomedins do?

Liver
They promote somatostatin release from the hypo, thus decreasing A Pit GH release

24

Two factors that primarily control GH secretion

GHRH secretion
Somatostatin Inhibition

25

What neurotransmitter systems stimulate GHRH and/or inhibit somatostatin. (receptor)

Catecholamines (alpha2 adrenergics)
Dopamine (D1 or D2 Receptors)
Excitstory AAs (NMDA and non-NMDA receptors)

26

The effects of catecholamines on GH would be seen in...

Chronic Stress

27

In the GH ultrashort feedback loop....

GHRH and Somatostatin both regulate their own secretion

28

Relationship of GH and insulin in carbohydrate intake

During carbohydrate intake, GH antagonizes insulin
Blocks Glu uptake to prevent hypoglycemia.

29

Relationship of GH and insulin during absorptive phase?

GH secretion is inhibited to allow glucose uptake

30

Relationship of GH and insulin when fasting?

Antagonizes insulin, helps mediate glucose sparing

31

Why can't normal serum samples to be used to assess GH?

Pulsatile pattern of release

32

What do you do to test blood for GH then?

Measure after exercise, immediately after sleep
Measure after Insulin-induced hypoglycemia
Measurement of IGF-1 (a somatomedin) to assess GH excess

33

Cause of Acromegaly and Gigantism?

Eosinophilic Adenomas of Somatotrophs

34

Difference between a person developing acromegaly or gigantism?

Acromegaly - hypersecretion after end of body growth
Gigantism -- hypersecretion before the end of body growth

35

Appearance of a patient with acromegaly

Growth of cancellous bones --> protruding jaw, hickenin phalanges, growth over visceral organs

36

ACTH is produced by proteolytic processing of...

Prepro-opiomelanocortin (POMC)

37

POMC products include...

ACTH
beta/gamma lipotropin
beta-endorphin
alpha-melanocyte stimulaitng hormone

38

ACTH is a key regulator of....

Stress Response

39

What does ACTH do?

Reulates the adrenal cortex and synthesis of adrenocorticosteroids

40

What does alpha-melanocyte stimulating hormone do?

Overproduction --> Increased pigmentation
Antipyretic and Antiinflammatory
May inhibit feeding

41

What is Addison's Disease?

Dysfunctional Adrenal Cortex
No cortisol from zona fasiculata --> Overproduction of ACTH
Skin Color Darkens

42

What do beta-endorphins do?

They bind to opiate receptors, generating a runner's high

43

Four factors that stimulate ACTH release?

Corticotropin releasing Hormone
ADH
Stress
Hypoglycemia

44

ADH =

Vasopressin

45

ADH deficiency will lead to what effect on ACTH?
Why?

Decreased ACTH release
ADH potentiates CRH at multiple levels and many vasopressinergic neurons also contain CRH, normally causing co-release

46

Pattern with which ACTH is released?

Circadian
-- Highest in early morning

47

ACTH's release pattern is opposite of what hormone?

GH

48

Two ways in which ACTH is regulated?

1. Cortisol inhibits hypothalamus and pituitary
2. ACTH inhibits hypothalamus

49

Effects of ACTH on adrenal cortex

Stimulates growth of cortex
Stimulated steroid hormone synthesis

50

What happens in Adrenogenital syndrome

Block of steroidogenesis, substrates shunted to testosterone
Masculinization of Female Fetus

51

Glycoprotein Hormones Include...

LH, FSH, TSH, and hCG

52

Structural similarities and differences of glycoprotein hormones

All have identical alpha subunit
beta subunits are unique

53

Synthesis and secretion of LH and FSH is stimulated by...

GnRH

54

FSH secretion is controlled by...

Inhibin

55

Describe the secretion pattens of LH/FSH

LH -- biphasic (every minute, then large at the hour)
FSH -- Uniphasic

56

Differences in the cyclic nature of LH/FSH in males and females

Cyclic in females with LH surge at time of ovulation
Males have constant pulses to maintain testosterone

57

Negative feedback mechanisms for LH/FSH

- Inhibin from testes/ovaries decreases FSH
- Testosterone inhibits GnRH production from hypo and
down regulates GnTH receptors
- Progesterone suppresses ovulation
- Dopamine, Endorphin, and Prolactin inhibit GnRH release

58

Overproduction of prolactin via a pituitary tumor can cause...
What do you do?

Amenorrhea
Shuts off GnRH
Treat w/ Dopamine or tumor removal

59

LH/FSH uses what positive feedback mechanism?

Estradiol at high plasma concentration in late follicular phase stims GnRH and LH Surge --> Ovulation

60

How is prolactin typically controlled?

It is tonically inhibited by dopamine

61

Prolactin releasing hormone is...

thyrotropin releasing hormone

62

Roles of Prolactin

Stims Breast Dev and Lactogenesis
May help Leydigs develop
Stimulates T cell function

63

How is Prolactin excess assessed?

Single basal serum PRL

64

Elevated PRL in a non-pregnant woman indicates...

Lesion that interferes with portal blood flow

65

Role of oxytocin

Stimulates myoepithelial contraction in uterus+mammary

66

Describe an example of prolactin becoming uninhibited

Suckling
Sensory Fibers --> Spine --> PVN -> Cholinergic synapses fire on oxytocin neurons and stimulate release

67

Describe the role of oxytocin in uterine contractions.

Reflexes originate in the cervical, vaginal, and uterus stimulate oxytocin synthesis and release.
Estrogen increases synthesis and lowers threshold for release.