Hypothalamic-Pituitary Flashcards

1
Q

Neurohypophysis

Functional relationship between hypothalamus & posterior pituitary gland

A
  1. PVN and SON of hypothalamus synthesize and send signal down to secrete **vasopressin & oxytocin **
  2. Magnocellular neurons send through infindiublar stalk to posterior pituitary
  3. Released into blood circulation; ultimately low concentration at target tissues, but high affinity
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2
Q

Stimulants of ADH (6)

A
  1. increase ECF osmolality
  2. Decrease in vol or pressure
  3. Pain, stress
  4. Increase in temp
  5. Beta adrenergic agonists
  6. Drugs: Nicotine, opiates, barbituates, sulfonylureas, antineoplastic agents
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3
Q

Inhibitors of ADH secretion (4)

A
  1. Decrease in temperature
  2. alpha adrenergic agonists
  3. ethanol
  4. ? Cortisol and thyroid hormone
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4
Q

What areas of the hypothalamus are associated with secretion of ADH and oxytocin?

A

Paraventricular nucleus (PVN)

&

Supraoptic nucleus (SO)

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5
Q

Functions of ADH & Oxytocin

A
  1. ADH: Regulates blood pressure by targeting kidney tubules to increase water reabsorption
  2. Targets smooth muscle (breast and uterus) for contractions
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6
Q

Adenohypophysis

Functional relationship between the hypothalamus and anterior pituitary gland

A
  1. Hypothalamus sends signals down median eminence through SHA
  2. Releasing factors act on cells; hypothalamic neurohormones
  3. Secretion of hormones from anterior pituitary to circulation –> target tissue
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7
Q

Releasing hormones of hypothalamus & anterior pituitary hormones

A
  1. GRH –> GH
  2. SS (Somatostatin) –x GH & TSH
  3. TRH —> TSH &PRL
  4. DA (Dopamine) –x PRL
  5. GnRH –> LH & FSH
  6. CRH —> ACTH, ß LPH, ß endor
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8
Q

Regulating hypothalamic releasing hormones (2)

A

Inhibiting hormones

Releasing hormones

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9
Q

Tissues affected by anterior pituitary hormones

A
  1. Growth hormone = bones
  2. Thyroid stimulating hormone = thyroid
  3. Prolactin = breats
  4. Leutenizing & follicle stimulating hormones = gonads
  5. ACTH = adrenal cortex –> glucocorticoids
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10
Q

Neuroendocrine system

A
  1. Rapid CNS of neurons and NT
  2. Long-lasting, amplified release of hormones
  3. Neurohormones: releasing factors from hypothalamus
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11
Q

Macroadenoma (5)

A
  1. Large pituitary tumors due to overproduction of hormones

*most common is Prolactin

  1. Due to presence of sphenoid bone, healthy tissue is pushed upwards
  2. Can impinge on optic chiasm & optic tracts= visual distrubances
  3. Can impinge on blood vessels in pituitary stalk = prevent flow to anterior pituitary =cell death
  4. Require surgical removal
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12
Q

Microadenoma (3)

A
  1. Often evade detection with imaging techniques
  2. Can measure hormone levels
  3. Treat with medical drug therapy
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13
Q

Long Loop Negative Feedback

A

RF (hypothalamus) –>

Stimulating hormone (anterior pituitary) –>

tropic hormone release –>

target organ –>

hormone release —>

Negative feedback on hypothalamus & anterior pituitary

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14
Q

Short loop negative feedback

A

Pituitary hormones —> hypothalamus

negative feedback

*occurs when hormone does not have a well-defined target gland

Ex: Growth hormone

Ex: prolactin b/c it stimulates an exocrine product; never enters circulatory system b/c milk is secreted (so it can’t do negative feedback)

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15
Q

Ultra short negative feedback

A

Releasing factor –> hypothalamus

  1. inhibitory recurrent collaterals back to cell body
  2. Inhibits firing of hypothalamus
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