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Physio 2 > Endocrine > Flashcards

Endocrine Flashcards

1
Q

anterior pituitary

A

Glandular-develops as an ectodermal evagination of oropharynx FLAT PG
linked to hypothalamus by the HYPOTHALAMIC-HYPOTHYSIAL PORTAL SYSTEM.
-blood containing high concentrations of hormones from hypothalamus is delivered directly to pituitary. e.g. GnRH stim/inhibs the release of GH from Ant. pit

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2
Q

posterior pituitary

A

derived from nervous tissue-neural extension of hypothalamus. Nerve cell bodies located in hypothalamic nuclei which synth hormones->packaged into secretory granules->transported down axons to the posterior pit for release into circulation.
ADH and Oxytocin-homologous nonapeptides SYNTHESIZED IN HYPOTHALAMIC NUCLEI and packaged in secretory granules with neurophysins.
No cell bodies, only axons and axon terminals

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3
Q

Hormones of ant. pit

A

FSH PRL
LH GH
ACTH
TSH

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4
Q

TSH, LH, FSH

A

same glycoprotein family, has identical alpha subunits, beta subunits are diff and responsible for unique biologic activity

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5
Q

ACTH, MSH, B-Lipotropin, B-endorphin

A

derived from a single precursor- Pro-opiomelanocortin(POMC) . MSH produced in intemediate lobe of pit. POMC-precursor for ACTH, B-lipotropin, B-endorphin

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6
Q

Growth Hormone (somatotropin)

A

most important for growth to normal adult size. Single polypeptide that is HOMOLOGOUS WITH PROLACTIN and human placental lactogen.

  • released in a pulsatile fashion
  • SECRETION IS INCREASED by sleep, stress, hormones related to puberty, starvation, exercise, hypoglycemia.
  • SECRETION IS DECREASED by somatostatin, somatomedins, obesity, hyperglycemia, pregnancy
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7
Q

1) Hypothalamic control-GHRH and somatostatin

A

GHRH stimulates the synthesis and secretion of GH.

SOMATOSTATIN inhibits secretion of GH by blocking the response of the ant. pit to GHRH

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8
Q

2) Negative feedback control by somatomedins

A

somatomedins produced when GH acts on target tissues. SOMATOMEDINS INHIBIT THE SECRETION OF GH by acting directly on the ant. pit and by stimulating secretion of somatostatin from the hypothalamus

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9
Q

3) Negative feedback control by GHRH and GH

A

GHRH inhibits its own secretion from hypothalamus. GH also inhibits its own secretion by stimulating the secretion of somatostatin from hypothalamus.

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10
Q

Actions of GH

A

In liver-GH generates the production of somatomedins [insulin-like growth factors (IGF)].. the IGF receptor has tyrosine kinase activity similar to insulin receptor.

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11
Q

Direct actions of GH

A
  1. decrease glucose uptake into cells(diabetogenic)
  2. increase lipolysis
  3. increase protein synthesis in muscle and increase lean body mass
  4. increse production of IGF
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12
Q

Actions of GH via IGF

A
  1. increase protein synthesis in chondrocytes and increase LINEAR GROWTH(growth spurt)
  2. increase protein synthesis in muscle and increase lean body mass
  3. increase protein synthesis in most organs and increase organ size.
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13
Q

GH deficiency

A

children: failure to grow, short stature, mild obesity, delayed puberty . . . due to:
1. lack of ant. pit GH
2. hypothalamic dysfunction (decrease GHRH)
3. failure to generate IGF in liver
4. GH receptor deficiency

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14
Q

GH excess

A

treat w/ somatostatin analogs(octreotide) which inhibit GH secretion.
Hypersecretion causes acromegaly:
a) before puberty, increased linear growth-gigantism
b) after puberty, increased periosteal bone growth, increased organ size, glucose tolerance

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15
Q

Prolactin (PRL)

A

LACTOGENSIS! works with estrogen in breast development and is structurally homologous to GH.

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16
Q

Regulation of prolactin secretion

A
  1. hypothalamic control by dopamine and thyrotropin-releasing hormone (TRH).
    - tonically inhibited by dopamine, prolactin inhibiting factor(PIF)–> interruption of hypothalamic-pituitary tract causes increased secretion of prolactin and sustained lactation
    - TRH increases prolactin secretion
17
Q

Negative feed-back control

A

PRL inhibits its own secretion by stimulating the hypothalamic release of dopamine.

18
Q

Actions of Prolactin

A
  1. stimulates milk production in the breast(casein, lactalbumin)
  2. stimulates breast development-supports estrogen
  3. inhibits ovulation by decreasing synthesis and release of Gonadotropin Releasing Hormone (GnRH)
  4. inhibits spermatogenesis by decreasing GnRH
19
Q

PRL deficiency (destruction of ant pit)

A

results in failure to lactate.

20
Q

prolactin excess

A

results from hypothalamic destruction(loss of tonic inhibitory control by dopamine)
causes galactorrhea and decreased libido. Causes failure to ovulate, and amenorrhea b/c it inhibits GnRH secretion. TX w/ bromocriptine, which reduces PRL secretion by acting as a dopamine agonist.

21
Q

Antidiuretic Hormone (ADH)

A

originates primarily in the supraoptic nuclei of hypothalamus. Regulates serum osmolarity by increasing the h2o permeability of the late distal tubules and collecting ducts.

22
Q

Factors that INCREASE ADH secretion

A 
increased serum osmolarity
volume contraction
pain
nausea(powerful stimulant)
hypoglycemia
nicotine, opiates, antineoplastic drugs
23
Q

Factors that DECREASE ADH secretion

A

decreased serum osmolarity
ethanol
alpha-agonists
ANP

24
Q

Actions of ADH

A
  1. increase water permeability of the principal cells of the late distal tubule and collecting duct via V2 receptor and adenylate cyclase-cAMP mech.
  2. constriction of vascular smooth muscle via a V1 receptor and a IP3/Ca++ mech
25
Q

Oxytocin

A

originates primarily in the paraventricular nuclei of the hypothalamus. Causes ejection of milk from breast when stimulated by suckling.

26
Q

Regulation of Oxytocin secretion

A
  1. Suckling-major stim for secretion, afferent fibers carry impulses from nipples to SC->relays info to hypothalamus which triggers release from post. pit.
    - sight or sound of infant may also stim hypothalamic neurons to secrete oxytocin in absence of suckling.
  2. Dilation of the cervix and orgasm increase the secretion of oxytocin
27
Q

Actions of Oxytocin

A
  1. contraction of myoepithelial cells in breast- milk is forced from mammary alveoli to ducts and delivered to infant.
  2. Contraction of the uterus-oxytocin receptors are up-regulated during pregnancy as parturition approaches.
    - can be used to induce labor and REDUCE POST-PARTUM BLEEDING.
28
Q

What tissues secrete steroids?

A

Gonads, placenta, skin, adrenal cortex.

NOT pituitary or adrenal medulla

29
Q

What tissues secrete other non-polar hormones?

A

Thyroid-secretes non-polar hormones, but they interact with INTRACELLULAR RECEPTORS similar to

Physio 2 (6 decks)

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