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Physiology II Exam III > Adrenal Hormones > Flashcards

Adrenal Hormones Flashcards

1
Q

What does the cortex of the adrenal cortex do?

A

-secretes corticosteroids

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2
Q

How are corticosteroids made?

A
  • synthesized from cholesterl -> provided mostly by LDLs in the plasma
  • most attach to coated pits
  • ACTH increases number of LDL receptors
  • cholesterol converted to pregnenolone in mitochondria
  • enzyme for conversion = cholesterol desmolase (RATE LIMITING STEP)
  • both ACTH and angiotensin II increase the conversion of cholesterol to pregnenolone
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3
Q

What are the corticosteroids?

A
  • progesterone
  • deoxycorticosterone
  • aldosterone
  • cortisol
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4
Q

What is the major mineralocorticoid?

A

Aldosterone

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5
Q

How do mineralocorticoids affect electrolytes?

A
  • increases Na reabsorption by kidney tubules -> principal cells in distal tubule
  • hyperkalemia increases aldosterone
  • increases K secretion by kidneys -> principal cells in distal tubule
  • increases H+ secretion by kidneys -> intercalated cells in distal tubules
  • secretion is controlled by angiotensin II and K+
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6
Q

What secretes mineralocorticoids?

A

-zona glomerulosa

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7
Q

What is the major glucocorticoid?

A

-cortisol -> essential in stress response

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8
Q

What is the secretion of glucocorticoids controlled by?

A

-secretion controlled mainly by ACTH
+uporegulates its own receptor
+under the influence of CRH
+second messenger for both CRH and ACTH is cAMP

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9
Q

What secrets glucocorticoids?

A

-zona fasciculata

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10
Q

What does cortisol have a negative feedback response on?

A

-CRH and ACTH

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11
Q

How is cortisol regulated with the circadian rhythm?

A
  • highest cortisol levels before waking

- lowest in the evening

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12
Q

What are androgen if hormones?

A

-19 carbon steroids that are precursors to the estrogens
+DHEA and androstenedione

+DHEA is converted to testosterone in the testes

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13
Q

Adrenal androgens are. Excreted. As ______________ in the urine.

A

17-ketosteroids

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14
Q

How do 18 carbons steroids have estrogen in activity?

A

-oxidation of one of the rings occurs in the ovaries to produce estrogens, but not in the adrenal glands or testes

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15
Q

What secretes androgens can hormones?

A

-zona reticularis

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16
Q

What happens when there is a lack of aldosterone in the body?

A
  • total loss causes death in days unless extensive salt therapy and mineralocorticoid injections are available
  • w/o mineralocorticoids K levels in ECF rise and Na and Cl are lost rapidly from urine
  • total ECF and blood volume become greatly reduced
  • person develops diminished cardiac output and progresses to a shock like state
  • hyperkalemia and serious cardiac toxicity
17
Q

What happens when there is an excess of aldosterone?

A
  • increase in ECF and arterial pressure
  • small effect on plasma Na conc -> Na absorption in renal tubules is accompanied by equivalent amount of water reabsorption
  • hypokalemia and muscle weakness
  • stimulates transport of K from ECF into most cells of the body
  • causes alkalosis (H+ secreted in exchange for Na+)
18
Q

Overall effect of aldosterone.

A

-increases renal tubular reabsorption of Na and increases K in the urine

19
Q

Cellular sequence of events leading to Na reabsorption.

A
  1. Aldosterone is lipid soluble and diffuse readily into the interior of the tubular epithelial cells
  2. Aldosterone combines with mineralocorticoid receptor proteins
  3. Aldosterone receptor complex diffuses into nucleus
  4. RNA transcription is induced
  5. Na-K ATPase pump proteins are among those formed as a result of this induction
  6. Epithelial sodium channel is also formed
20
Q

How is aldosterone regulated?

A
  • almost entirely independent of the regulation of cortisol secretion
  • increased K conc greatly increases aldosterone secretion
  • increased angiotensin II conc greatly increases aldosterone secretion
  • ACTH necessary for aldosterone secretion but has little effect in controlling rate of secretion
21
Q

What are the functions of glucocorticoids?

A
  • stimulates gluconeogenesis -> may lead to adrenal diabetes
  • resists stress
  • resists inflammation
  • causes resolution of inflammation
  • inhibits immune response
  • maintains vascular response to catecholamines
22
Q

How do glucocorticoids stimulate gluconeogenesis?

A
  • increases protein catabolism
  • mobilizes aas from extra hepatic tissues
  • enhances transport of aas into hepatic cells
  • increases enzymes requires to convert aas to glucose
  • decreases glucose utilization by cells
  • increases lipolysis
23
Q

How can glucocorticoids resist inflammation?

A
  • induces synthesis of lipocortin which inhibits phospholipase
  • inhibits production of interleukin-2
  • inhibits release of histamine and serotonin
  • blocks inflammatory response to allergic reaction
  • decreases number of eosinophils and lymphocytes in blood
24
Q

What are the primary and secondary reasons for hypoadrenalism/ Addison’s disease?

A

Primary: due to injury to adrenal cortex

Secondary: due to impaired function of pituitary gland

25
Q

What are some disturbances of Addison’s disease?

A
  • due to mineralocorticoid deficiency
  • due to glucocorticoid deficiency
  • melanin pigmentation
26
Q

What are some effects of mineralocorticoid deficiency?

A
  • decreased extracellular fluid volume
  • hyponatremia
  • hyperkalemia
  • mild acidosis
  • rise in RBC conc
  • decrease in cardiac output
  • decrease in blood pressure
  • metabolic acidosis
  • death from shock
27
Q

What are some effects of glucocorticoid deficiency?

A
  • loss of ability to maintain normal blood glucose conc between meals -> hypoglycemia
  • reduction in both proteins and fats leading to depression of othe bodily functions
  • weight loss, nausea, vomiting
  • muscle weakness
  • highly susceptible to stress
28
Q

What are some effects in the disturbance of melanin pigmentation?

A
  • may be caused by loss of negative feedback to pituitary, allowing increased amounts of MSH
  • results in uneven distribution of pigmentation especially in thin skin areas
29
Q

What are some causes of hyper adrenaline/ Cushing’s disease?

A
  • administration of glucocorticoids
  • adenoids of anterior pituitary
  • abnormal function of hypothalamus
  • ectopic secretion of ACTH by tumor
  • adenomas of adrenal cortex
  • excess ACTH secretion is cause of Cushing’s
30
Q

What are some of the characteristics of Cushing’s disease?

A
  • increase in cortisol and androgen levels
  • “buffalo torso”
  • moon face
  • acne and hirsutism
  • hypertension
  • increased blood glucose
  • increase in protein catabolism and muscle wasting
31
Q

What does the medulla of the adrenal gland do?

A
  • secretes epi and NE

- functionally related to sympathetic nervous system

Physiology II Exam III (9 decks)

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