Lecture 22: Adrenal Hormones Flashcards Preview

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

Flashcards in Lecture 22: Adrenal Hormones Deck (53):
1

What hormone is secreted by the adrenal medulla?

- epinephrine
- norepinephrine

2

What is the adrenal medulla functionally related to?

Sympathetic Nervous System

3

What hormones are secreted by the adrenal cortex?

> Secretes Corticosteroids:
- mineralocorticoids
- glucocorticoids
- androgenic hormones

4

What molecule are corticosteroids synthesized from?

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.

5

What provides most of the cholesterol for synthesis of corticosteroids?

LDLs in the plasma.

6

What does ACTH do to LDL receptors?

Increases number of LDL receptors.

7

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

mitochondria

8

What enzyme converts cholesterol to pregnenolone in the mitochondria?

cholesterol desmolase

**rate-limiting step**

9

What two products increase the conversion of cholesterol to pregnenolone?

Both ACTH and angiotension II.

10

List the 21-carbon steroids (corticosteroids).

- Progesterone
- Deoxycorticosterone
- Aldosterone
- Cortisol

11

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

ADH

12

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

Angiotension II

13

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

Cortisol (glucocorticoid)

14

What is the progression of progesterone to aldosterone?

> progesterone is hydroxylated at C-21 to form deoxycorticosterone

> then aldosterone is formed from deoxycorticosterone.

15

What hormone is the major mineralocorticoid?

aldosterone

*half-life is about 20 minutes*

16

What is the function of aldosterone on electrolytes?

> 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

17

What mainly controls the secretion of aldosterone?

- angiotension II
- K+ concentration

18

What layer of the adrenal cortex secretes aldosterone?

zona glomerulosa

19

Look over slide 10.

Aldosterone regulation mechanism.

20

What hormone is the major glucocorticoid?

Cortisol

21

What response is corticol essential for?

Stress Response

22

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

ACTH

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

23

What second messenger controls both CRH and ACTH?

cAMP

24

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

zona fasciculata

25

True or False:

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

True

26

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

> Normally high = before waking.

> Normally low = in the evening.

27

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

19-carbon

- DHEA
- androstenedione

28

Where is DHEA converted to testosterone at?

testes

29

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

17-ketosteroids

30

Steroids containing how many carbons have estrogenic activity?

18-carbon

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

31

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.

True

32

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

zona reticularis

33

What are the effects of insufficient aldosterone secretion?

> 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

What are the effects of excess secretion of aldosterone?

> 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

True or False:

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

True

36

List the cellular sequence of events leading to sodium reabsorption.

(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

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

Aldosterone-responsive epithelial cell signaling pathways.

38

True or False:

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

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

39

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

Greatly increases aldosterone secretion.

40

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

Greatly increases aldosterone secretion.

41

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

ACTH

42

What are the functions of glucocorticoids (cortisol)

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

43

What are the effects of glucocorticoids on stimulating gluconeogenesis?

- 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

What are the effects of glucocorticoids in resisting inflammation?

- 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

What disease is caused by primary hypoadrenalism?

Addison's Disease

46

What is Addison's disease caused by?

Due to injury to adrenal cortex.

47

What is secondary hypoadrenalism caused by?

Due to impaired function of pituitary gland.

48

List disturbances that can cause hypoadrenalism.

- Due to mineralocorticoid deficiency.

- Due to glucocortiocid deficiency.

- Melanin pigmentation.

49

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

- 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

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

- 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

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

- 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

List causes of hyperadrenalism (Cushing's Disease).

- 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

What are the characteristics seen in patients with hyperadrenalism - Cushing's disease?

- Increase in cortisol and androgen levels.
- "Buffalo torso"
- Moon face
- Acne and hirsutism
- Hypertension
- Increased blood glucose
- Increase in protein catabolism and muscle wasting.