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Human Physiology 2 - Unit 3 - Zach H. > Lecture 22: Adrenal Hormones > Flashcards

Lecture 22: Adrenal Hormones Flashcards

1
Q

What hormone is secreted by the adrenal medulla?

A
  • epinephrine

- norepinephrine

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2
Q

What is the adrenal medulla functionally related to?

A

Sympathetic Nervous System

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3
Q

What hormones are secreted by the adrenal cortex?

A

> Secretes Corticosteroids:

 - mineralocorticoids 
 - glucocorticoids 
 - androgenic hormones
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4
Q

What molecule are corticosteroids synthesized from?

A

Cholesterol

> 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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5
Q

What provides most of the cholesterol for synthesis of corticosteroids?

A

LDLs in the plasma.

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6
Q

What does ACTH do to LDL receptors?

A

Increases number of LDL receptors.

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7
Q

In the synthesis of corticosteroids, where in the cell is cholesterol converted to pregnenolone?

A

mitochondria

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8
Q

What enzyme converts cholesterol to pregnenolone in the mitochondria?

A

cholesterol desmolase

rate-limiting step

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9
Q

What two products increase the conversion of cholesterol to pregnenolone?

A

Both ACTH and angiotension II.

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10
Q

List the 21-carbon steroids (corticosteroids).

A
  • Progesterone
  • Deoxycorticosterone
  • Aldosterone
  • Cortisol
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11
Q

In the synthesis of steroid hormones, what hormone activates cholesterol desmolase to convert cholesterol to pregnenolone in the mitochondria?

A

ADH

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12
Q

In the synthesis of steroid hormones, what molecule stimulates aldosterone synthase (P450 c11AS) to convert coricosterone to aldosterone?

A

Angiotension II

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13
Q

What hormone is produced by the hydroxylation at C-17 of progesterone?

A

Cortisol (glucocorticoid)

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14
Q

What is the progression of progesterone to aldosterone?

A

> progesterone is hydroxylated at C-21 to form deoxycorticosterone

> then aldosterone is formed from deoxycorticosterone.

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15
Q

What hormone is the major mineralocorticoid?

A

aldosterone

half-life is about 20 minutes

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16
Q

What is the function of aldosterone on electrolytes?

A

> Increases Na reabsorption by kidney tubules.
- principal cells in late distal tubule

> Hyperkalemia increases aldosterone secretion.

> Aldosterone increases K secretion by kidneys.
- acts on principal cells in late distal tubule

> Aldosterone increases H ion secretion by kidneys.
- acts on interacalated cells in late distal tubule

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17
Q

What mainly controls the secretion of aldosterone?

A
  • angiotension II

- K+ concentration

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18
Q

What layer of the adrenal cortex secretes aldosterone?

A

zona glomerulosa

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19
Q

Look over slide 10.

A

Aldosterone regulation mechanism.

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20
Q

What hormone is the major glucocorticoid?

A

Cortisol

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21
Q

What response is corticol essential for?

A

Stress Response

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22
Q

Which hormone, released from the anterior pituitary, mainly controls secretion of cortisol?

A

ACTH

> ACTH up-regulates it own receptor.
Under the influence of CRH
Second messenger for both CRH and ACTH is cAMP.

23
Q

What second messenger controls both CRH and ACTH?

24
Q

Which layer of the adrenal cortex is cortisol (glucocorticoid) secreted by?

A

zona fasciculata

25
Q

True or False:

Cortisol has a negative feedback response to both CRH and ACTH.

26
Q

Cortisol levels oscillate with the circadian rhythm. When is it the highest and when is it the lowest?

A

> Normally high = before waking.

> Normally low = in the evening.

27
Q

Steroids containing how many carbons have androgenic activity and are precursors to the estrogens?

A

19-carbon

  • DHEA
  • androstenedione
28
Q

Where is DHEA converted to testosterone at?

29
Q

What what form are adrenal androgens excreted in the urine as?

A

17-ketosteroids

30
Q

Steroids containing how many carbons have estrogenic activity?

A

18-carbon

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

31
Q

True or False:

Oxidation of one of the rings of a 19-carbon steroid that has androgenic activity occurs in the ovaries to produce estrogens (18-carbon steroid), but not in the adrenal glands or testes.

32
Q

What layer of the adrenal cortex is androgenic hormones secreted by?

A

zona reticularis

33
Q

What are the effects of insufficient aldosterone secretion?

A

> Total loss causes death in a matter of days.

> Without mineralcorticoids K levels in ECF rise markedly and Na and Cl ions are lost rapidly from the urine.

> Total ECF and blood volume become greatly reduced.

> Person develops diminished cardiac output and progress to a shock-like state.

> Hyperkalemia and serious cardiac toxicity.

34
Q

What are the effects of excess secretion of aldosterone?

A

> Increase in ECF and arterial pressure.

> Small effect on plasma [Na] - because Na reabsorption 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 (hydrogen ions are secreted in exchange for sodium).

35
Q

True or False:

Aldosterone increases renal tubular reabsorption of sodium and increases potassium in the urine.

36
Q

List the cellular sequence of events leading to sodium reabsorption.

A

(1) Aldosterone is lipid soluble and diffuses 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) Sodium-potassium ATPase pump proteins are among those formed as a result of this induction.
(6) Epithelial sodium channel (ENaC) is also formed.

37
Q

Look over and know figure 78-4. Also know the effects of spironolactone and amiloride on aldosterone signaling.

A

Aldosterone-responsive epithelial cell signaling pathways.

38
Q

True or False:

The regulation of aldosterone and cortisol secretion are dependent on one another.

A

False - aldosterone secretion is almost entirely independent of the regulation of cortisol secretion.

39
Q

What effect on aldosterone secretion regulation does an increased potassium ion concentration have?

A

Greatly increases aldosterone secretion.

40
Q

What effect on aldosterone secretion regulation does an increased angiotensin II concentration have?

A

Greatly increases aldosterone secretion.

41
Q

Which hormone is necessary for aldosterone secretion but has little effect in controlling the rate of secretion of aldosterone?

42
Q

What are the functions of glucocorticoids (cortisol)

A 
> Stimulates gluconeogenesis 
> May lead to "adrenal diabetes"
> Resists stress 
> Resists inflammation 
> Causes resolution of inflammation
> Inhibits immune response 
> Maintains vascular response to catecholamines
43
Q

What are the effects of glucocorticoids on stimulating gluconeogenesis?

A
  • Increases protein catabolism.
  • Mobilizes amino acids from extrahepatic tissues.
  • Enhances transport of amino acids into hepatic cells.
  • Increases enzymes required to convert amino acids to glucose.
  • Decreases glucose utilization by cells.
  • Increases lipolysis.
44
Q

What are the effects of glucocorticoids in resisting inflammation?

A
  • Induces synthesis of lipocortin which inhibits phospholipase.
  • Inhibits production of IL-2
  • Inhibits release of histamine and serotonin.
  • Blocks inflammatory response to allergic reactions.
  • Decreases number of eosinophils and lymphocytes in blood.
45
Q

What disease is caused by primary hypoadrenalism?

A

Addison’s Disease

46
Q

What is Addison’s disease caused by?

A

Due to injury to adrenal cortex.

47
Q

What is secondary hypoadrenalism caused by?

A

Due to impaired function of pituitary gland.

48
Q

List disturbances that can cause hypoadrenalism.

A
  • Due to mineralocorticoid deficiency.
  • Due to glucocortiocid deficiency.
  • Melanin pigmentation.
49
Q

List specific results seen in patients with hypoadrenalism that is due to a mineralocorticoid deficiency.

A
  • Decreased extracellular fluid volume.
  • Hyponatremia
  • Hyperkalemia
  • Mild acidosis
  • Rise in RBC concentration
  • Decrease in cardiac output
  • Decrease in blood pressure
  • Metabolic acidosis
  • Death from shock
50
Q

List specific results seen in patients with hypoadrenalism that is due to a glucocorticoid deficiency.

A
  • Loss of ability to maintain normal blood glucose concentrations between meals -> hypoglycemia.
  • Reduction in both proteins and fats leading to depression of other bodily functions.
  • Weight loss, nausea, vomiting.
  • Muscle weakness.
  • Highly susceptible to stress.
51
Q

List specific results seen in patients with hypoadrenalism that is due to a melanin pigmentation deficiency.

A
  • May be caused by loss of negative feedback to pituitary, allowing increased amounts of MSH.
  • Results in uneven ditribution of pigmentation, especially in thin skin areas.
52
Q

List causes of hyperadrenalism (Cushing’s Disease).

A
  • Administration of glucocorticoids.
  • Adenomas 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.
53
Q

What are the characteristics seen in patients with hyperadrenalism - 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.

Human Physiology 2 - Unit 3 - Zach H. (9 decks)

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