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Flashcards in Hypothalamus and pituitary Deck (63):
1

Where is the pituitary gland located?

At the base of the brain in a bony pocket called sella turcica.

2

How is the pituitary gland connected to the brain?

Stalk of tissue called the infundibulum containing nerves and special veins (long portal veins)

3

What are the parts of the pituitary gland?

Anterior lobe- pars distalis+ pars tuberalis
Posterior lobe- pars nervosa + pars intermedia

4

What are the 2 parts of the hypothalamus? What do they do?

1. Nuclei: clusters of nerve cells bodies that synthesize hypothalamic RH that regulats secretion of hormone from the anterior pit. gland and 2 posterior pit gland hormones (ADH/ OT)
2. Bottom portion: median eminence. Axon terminals containing hypothalamic RH. These RHs are secreted FIRST into capillaries of a portal system.

5

What hormones are produced by the posterior pituitary gland?

OT and ADH

6

Nerve axons at the posterior pituitary mainly come from? Where do they terminate?

2 nuclei in the hypothalamus- supraoptic nucleus and paraventricular nucleus
Near capillaries in the posterior pituitary. Stores and release hormones here.

7

Describe the structure of the pars nervosa of the posterior lobe

Neurosecretory nerve fibers from PV and SON
- Hypothalamohypopsheal T

8

What cell is associated with the pars nervosa of the posterior lobe of the pituitary

pituicytes

9

Function of pars nervosa of posterior lobe of pituitary

release of oxytoxin and ADH

10

What does oxytoxin do?

stimulates contraction of smooth muscle in pregnant uterus and myoepitherlial cells in mammary gland.

11

What does ADH do?

regulates body retention of water. Increases contracility of arterial smooth muscle to increase BP. Increase water reabsorption

12

Describe the structure of ADH and OT

nonapeptides with S-S, similar structures and overlapping activities

13

Describe the synthesis of ADH and OT

synthesized as much larger molecules (pro-), stored in granules with neurophysins I and II

14

Describe the secretion of ADH and OT

Secreted-when action potentials reach nerve terminals; analgous to neurotransmitter release secreted together with their respective neurophysins

15

What 2 things cause secretion of oxytocin?

dilation of cervix, suckling

16

What is the main stimuli of ADH?

decrease ECF volume (also increase osmolarity)

17

Where are osmoreceptors located?

hypothalamus: OVLT (SON and PVN?)

18

What does the intermediate lobe of the pituitary gland do?

It MAY secrete MSH.

19

What major hormones are secreted by the anterior pituitary?

GH, PRL, ACTH, FSH, LH, TSH

20

Chemical nature of ACTH

peptide that is split from POMC (pro-opiomelancortin). 39 aa straight chain. C terminus has most antigenic activity.
Only 20 aa @ N-terminus needed for biological activity

21

What is ACTH1-24?

ACTH structure that has full activity

22

What is MSH do?

stimulates synthesis of melanin in melanocytes- darkens skin

23

Where is the structure of MSH? What does this cause?

lies within ACTH- excess ACTH causes hyperpigmentation

24

What hormones secreted by anterior pituitary are glycoproteins?

TSH, FSH, LH

25

What cells make up 15-20% of pituitary volume?

basophils

26

What is the structure of the anterior pituitary glycoproteins?

dimers of a and b subunits. A is very similar among all 3 hormones. B is fairly similar.

27

What cells are stained to measure GH and PRL?

acidophils

28

___ causes release of granules from posterior pituitary?

Action potentials

29

How do hormones get from hypothalamus to posterior pituitary?

Axon flow

30

How do hormones get from hypothalamus to anterior pituitary?

the hypothalamo-pituitary portal system- 2 capillary beds!

31

What kind of tissue makes up the pituitary?

Anterior: glandular
Posterior: neural secretory

32

Neural extensions to the posterior pituitary from the hypothalamus come from _____.

2 nuclei--> SON and PVN

33

Oxytocin increases the contracility of _____

uterine smooth muscle and mypoepithelial cells of mammary glands--> milk let down

34

2 main oxytocin stimuli

suckling and dilation of cervix

35

What are the 2 main stimuli for ADH?

decrease in plasma volume by 5-10%
Increase osmolarity by 1-2%

36

In what 2 ways is ADH an example of negative feedback?

1. Water rebsorption negatively acts on osmolality so it doesnt act on SON and PVN
2. Increase plasma volume negatively acts on volume receptors so they dont signal to CNS

37

What are the effects of stalk section on nerve tracts to posterior pituitary?

(transient diabetes insipidus)
1. Polyuria
2. Polydipsia
3. Nerve terminals develop and capillaries regrow (reversible)

38

In order to have an affect hormones have to diffuse in the _____.

hypopophyseal veins

39

What are the 6 cells in anterior pituitary? Which are basophils and which are acidophils?

Baso: FSH, LH, TSH, ACTH
Acid: GH, PRL

40

What subunit of glycoprotein do you measure?

beta!

41

Acidophils make up ____ of the ant. pituitary. What makes up this?

75%; 50% somatotrophs; 15-25 Lactotrophs

42

Target tissue of ACTH

adrenal cortex

43

Major actions of ACTH

increase adrenal growth, cortisol synthesis, cortisol secretion, plasma concentration of cortisol (--> vascular reactivity and gluconeogenesis)

44

Variables that increase release of ACTH

increase CRH, Stress, morning time, decrease of cortisol, removal of adrenal/s

45

Variable that decrease release of ACTH

decrease CRH, decrease stress, later in the day, increase cortisol, Rx ith glucocorticoids

46

Target tissue of TSH

thyroid gland cells lining follicles

47

Some major actions of TSH

increase thyroid growth, TH syn and secretion, TH concentration, iodide trapping, thy blood flow, and everything that T3 and 4 do--> increase metabolic rate

48

Variables that increase TSH

increase TRH, decrease T4 and 3, low iodide diets, removal of thyroid gland

49

Things that decrease release of TSH

decrease TRH, increase T4/3, increase SS, Rx with THs

50

Increase GnRH increases the secretion of what?

FSH, LH in males and females

51

What are all the RH and what do they increase?

CRH--> ACTH
TRH--> TSH
GnRH--> LH and FSH
GHRH--> GH
SS--> decrease GH
Dopamine--> decrease PRL

52

What is the long loop of feedback?

Target organ hormone negatively acts on Anterior pituitary and can -/+ affect hypothalamus

53

What is the short loop of feedback?

ALWAYS -
hormone released from anterior pituitary - on hypothalamus

54

Target tissue of PRL

Females: mammary glands
Males: testes, 2nd sex tissues

55

Some major actions of PRL

Female: glandular tissue growth, milk synthesis
Male: potentiate LH and testost. actions

56

Variables that increase PRL

Decrease PIH, Increase TRH, suckling

57

Variables that decrease PRL

increase PIH, stop nursing

58

Target tissue of GH

msot cells of body esp muscle liver, cartilage in growth plates

59

Variables that increase GH

increase GHRH AND decrease SS
Deep sleep, hypoglycemia, acute stress

60

Variables that decrease GH

decrease GHRH and/or increase SS

61

To increase ADH secretion, there must be a _____% decrease in plasma volume and a ______% increase in osmolarity.

5-10%, 1-2%

62

Which is more sensitive to changes in circulating volume, RAS or ADH?#

RAS. ADH responds only to large decreases.

63

Low levels of ____ support increased secretion of ADH. #

ANP