Hypothalamic-Pituitary-Adrenal Axis Flashcards

1
Q

What 6 things does the hypothalamus regulate? How does it do this?

A
  1. maintenance of homeostasis
  2. reproduction
  3. metabolism
  4. eating and drinking behavior
  5. energy utilization
  6. osmolarity and blood pressure

secretes hormones via the pituitary

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2
Q

What is the hypothalamic-pituitary-adrenal axis?

A
  • hypothalamus secretes CRH to stimulate the anterior pituitary
  • in response, anterior pituitary secretes ACTH, which stimulate cortisol metabolism and secretion from the adrenals
  • increased cortisol in the bloodstream acts a negative feedback loop, which decreases CRH and ACTH production
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3
Q

What are the 3 zones of the adrenal cortex? What hormones do they secrete?

A
  1. zona glomerulosa - mineralocorticoids - aldosterone (SALT)
  2. zona fasciculata - glucocorticoids - cortisol, corticosterone (SUGAR)
  3. zona reticularis - sex hormones - androgens, estrogen (SEX)
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4
Q

What hormones are secreted by the adrenal medulla?

A

catecholamines - epinephrine, norepinephrine

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5
Q

What is responsible for cortisol release from the adrenal glands? What are 4 of its roles?

A

ACTH stimulation from the anterior pituitary

  1. regulates macronutrient metabolism
  2. maintain GI structure and function
  3. maintain normal BP
  4. stress adaptation - trauma, surgery, illness, pain, inflammation
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6
Q

What is responsible for aldosterone release from the adrenal glands? What are 2 of its roles?

A

RAAS - increased serum K = increased aldosterone, decreased serum K = decreased aldosterone

  1. increases ECF Na+ and H2O concentration
  2. decreases ECF K+ concentration
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7
Q

What is responsible for catecholamine release from the adrenal medulla? What are 5 of their roles?

A

stress, pain, injury, SNS stimulation = norepinephrine and epinephrine release

FIGHT OR FLIGHT

  1. vasoconstriction
  2. increased HR and contractility
  3. vasodilation of smooth muscles (beta-stimulation)
  4. glycogenolysis and gluconeogenesis to increase glucose availability
  5. lipolysis, increased metabolic rate
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8
Q

What are the likely results of pituitary tumors, adrenal cortical tumors, and adrenal medullar tumors?

A

increased ACTH = increased cortisol (Cushings)

increased cortisol (Cushing) and aldosterone (cats) secretion

(pheochromocytoma) excess and episodic release of catecholamines

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9
Q

What is primary and secondary hypoadrenocorticism? How are they different?

A

non-functional pituitary gland = decreased cortisol, normal aldosterone = normal electrolytes

destruction of the zona glomerulosa and fasciculata = decreased cortisol and aldosterone = cortisol and mineralocorticoid deficiency (most common, dogs)

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10
Q

What is the normal axis associated with growth hormone production? What are 3 aspects to its negative feedback loop?

A
  • hypothalamus secretes GHRG, which stimulates the anterior pituitary gland
  • in response, the pituitary gland secretes GH
  • GH induced the liver to produce IGF-1
  1. increased IGF-1 stops the production of GH from the pituitary and GHRH
  2. increased GH self-regulates and decreases GHRH
  3. somatostatin from the hypothalamus blocks this pathway
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11
Q

What are 4 functions of growth hormone?

A
  1. insulin antagonism
  2. lipolysis
  3. protein synthesis
  4. epiphyseal growth
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12
Q

What are 4 functions of IGF-1?

A
  1. insulin-like activity
  2. antilipolytic activity
  3. protein synthesis
  4. epiphyseal growth
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13
Q

What is acromegaly?

A

pituitary tumor results in secretion of GH and increase in IGF-1 from the liver

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14
Q

What hormones are produced by the posterior pituitary?

A
  • ADH
  • oxytocin
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