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Flashcards in 5.2 HPT Axis Deck (45):
0

Hypophysis is connected to the hypothalamus via

Hypophysial stalk

1

Physiologically pituitary gland is divided into

Ant. Pituitary
Pars intermedia
Post. pituitary

2

Differentiate anterior and posterior pituitary glands regarding their secretion

Anterior - release of RELEASING HORMONES from hypothalamus brings about secretion
Posterior - reception of NERVE SIGNALS from hypothalamus brings about secretion of stored ADH and Oxytocin

3

Anterior pituitary is the site where the anterior pituitary hormones are SYNTHESIZED, STORED, and RELEASED. However, in the posterior pituitary, hormones are NOT synthesized, ONLY STORED and RELEASED. What synthesized ADH and Oxytocin?

ADH - supraoptic nuclei
Oxytocin - paraventricular nuclei

4

The negative feedback is only applicable to the ANTERIOR pituitary because

The ANTERIOR Pituitary is responsive to hypothalamic RELEASING HORMONES (not nerve signals --> POSTERIOR)

5

Type of negative feedback where X-stimulating hormone inhibits the hypothalamus

Short loop

6

Type of negative feedback where X-releasing hormone inhibits the hypothalamus

Ultra short loop

7

Type of negative feedback where X-hormone inhibits hypothalamus or ant. Pituitary gland

Long loop

8

For most anterior pituitary hormones, the hypothalamic releasing hormones are MOST important as well EXCEPT _______, an inhibitory hormone exerts more control

Prolactin

9

Hormone that stimulates ACTH secretion

CRH - corticotropin releasing hormone

10

TRH or thyrotropin releasing hormone stimulates which hormone secretion

stimulated TSH secretion and PRL - Prolactin secretion

11

Precursor of ADH

Prepropressophysin

12

It is a carrier protein during axonal transport

Neurophysin

13

ADH and Oxytocin are both SECRETORY PEPTIDES, synthesized as larger precursor and cleaved into: 1. _________, 2. _________, and 3. __________.

1. Active hormone
2. Neurophysin
3. Glycopeptide

14

It is the PRIMARY trigger of ADH secretion

Plasma osmolarity changes.
High plasma osm: increase ADH secretion
Low plasma osm: decrease ADH secretion

"Only a change of 1-2% plasma Osmolarity is needed to trigger ADH release."

15

It is secreted in response to plasma osm changes and DECREASE in blood volume

ADH

16

TRUE or FALSE
Increased level of plasma osmolarity (>280 mosm/kg) increases the release of ADH

TRUE.
Why?
^ plasma osm -> ^osmoreceptors (w/c draws out water and causes shrinkage) -> signals sent to posterior pituitary -> ADH secretion occurs -> ^cAMP -> recruitment of aquaporins -> ^ permeability of H2O -> ^H2O absorption -> v plasma osm back to normal

17

True or False. In the presence of ADH, collecting tubules are impermeable to water, meaning no reabsorption occurs.

False.

In the ABSENCE of ADH, collecting tubules are IMpermeable to water, meaning NO reabsorption occurs.

In the PRESENCE of ADH, aquaporins are able to reabsorb water, increased PERMEABILITY.

18

Three factors that influence decrease in ADH secretion

Low plasma osm
High ECF volume
Alcohol

19

Characterized by excess ADH
Effects are increase water retention, low plasma osm, hyponatremia, inappropriately concentrated urine

SIADH Syndrome of inappropriate ADH secretion

20

Secretion of growth hormone is described as

Pulsatile - secretion is in pulses with MAXIMAL burst during SLEEP
Lifetime pattern - increasing with progression from birth, HIGHEST during PUBERTY, after which GH decreases

21

Growth effects of GH. Is also mediated by

IGF-1

22

True or false. GH inhibiting the hypothalamus is a long loop regulation.

FALSE.
GH inhibiting the hypothalamus is a SHORT loop regulation.
IGF-1 inhibiting the hypothalamus is a LONG loop regulation.

23

Test used to determine excess of hormones

Suppression test

24

Test used to determine deficit of hormones

Stimulation test

25

excess GH
Gigantism: open epiphyseal plate; __________: closure of epiphyseal plate

Gigantism: open epiphyseal plate; ACROMEGALY: closure of epiphyseal plate

26

GH: cytokine receptor; ACTH: ___________

GH: cytokine receptor; ACTH: G-protein coupled receptor

27

GH: lifetime pattern; ACTH : _______ pattern

GH: lifetime pattern; ACTH : DIURNAL pattern

ACTH can be altered by changing wake-sleep cycle
NOTE: both GH and ACTH. Are pulsatile

28

________ secretion follows ACTH secretion

Cortisol

29

Request for cortisol administration is during
(explain why)

6-8AM because this is the peak of the diurnal pattern of ACTH secretion

30

How can diurnal pattern of ACTH secretion be altered

Changing sleep wake cycle

31

What does hypothalamus secrete to stimulate synthesis of ACTH

Corticotrophin Releasing Hormone (CRH)

32

CRH increases the transcription of

POMC gene

33

Effects of a lack in CRH

1. Impair the ACTH diurnal rhythm
2. Affects the response to stress

34

Function of BNP

Inhibits ACTH secretion and causes the expulsion of sodium and water in the urine

35

Stimulates ACTH secretion

Stress
Transition from sleep to wake
Norepinephrine
Ach
Serotonin

36

Inhibit secretion of ACTH

GABA
Endorphins

37

LH: estrogen and progesterone; FSH:

LH: estrogen and progesterone; FSH: estradiol and inhibin

38

When there is an excess of one hormone, it can "sit" on the other hormones. Explain what "sit" on means

An excess in one hormone may sit on the receptor of another hormone causing the effects of that other hormone to be manifested
Ex. Excess HCG can sit on the TSH receptor and cause some of the effects of TSH such as stimulation of the thyroid gland

39

The way by which releasing hormones of the hypothalamus reach the anterior pituitary

Hypophyseal portal system via the median eminence

40

ADH is synthesized by

Supraoptic nuclei of hypothalamus

41

Oxytocin is synthesized by

Paraventricular nuclei of hypothalamus

42

Oxytocin and ADH have the same amino acid residues except for two aa residues:

ADH: arginine and phenylalanine
Oxytocin: leucine and isoleucine

43

Direct metabolic effects of growth hormone

Protein synthesis
Fat lipolysis
Inhibited uptake of blood glucose
Gluconeogenesis
Insulin resistance

44

Indirect effects of growth hormone

Postnatal linear growth and somatic development
Proliferation of chondrocytes
Bone forming and soft tissue growth