1 - Adrenocortical Hormones

Question 1

The adrenal cortex secretes:

Answer 1

corticosteroids

Question 2

The adrenal medulla secretes:

Answer 2

Epinephrine and norepinephrine

Question 3

The three classes of corticosteroids released by the adrenal cortex are:

Answer 3

mineralocorticoids

glucocorticoids

androgens

Question 4

What is the gross function of mineralocorticoids?

Answer 4

They effect “minerals” aka electrolytes

Question 5

What is the gross function of glucocorticoids?

Answer 5

increase blood glucose concentration

(also effect protein and fat metabolism)

Question 6

The principal mineralocorticoid is _________

The principal glucocorticoid is _________

Answer 6

aldosterone

cortisol

Question 7

Describe the three layers of the adrenal cortex, including what they secrete and how secretion is controlled

Answer 7

1. Zona glomerulosa - only cells that secrete aldosterone, secretion of which is controlled by K and Angiotensin II
2. Zona fasciculata - middle, widest, secretes cortisol and corticosterone, secretion controlled by ACTH
3. Zona reticularis - inner zone, secretes adrenal androgens and small amounts of estrogen and glucocorticoids, regulated by ACTH

Question 8

Describe the relationship between aldosterone and cortisol secretion

Answer 8

They are completely independently regulated

ACTH has no effect on aldosterone

Angiotensin II has no effect on cortisol

Question 9

Approximately 80% of the cholesterol used for steroid synthesis is provided by _______

Answer 9

LDLs in circulating plasma

Question 10

What is the rate limiting step in all adrenal steroid formation?

Answer 10

the cleaving of cholesterol in the cell into pregnenolone by cholesterol desmolase

Question 11

Synthesis of steroid in the adrenal cortex occurs where in the cell?

Answer 11

mitochondria and ER

Question 12

How potent is dexamethasone compared to cortisol?

Answer 12

30x more potent

Question 13

If cortisol primarily effects glucose metabolism, why do high cortisol disease states also include electrolyte imbalances?

Answer 13

Cortisol also has slight mineralocorticoid action

Question 14

How is cortisol transported in the blood?

Answer 14

90-95% bound to cortisol-binding globulin

Question 15

How is aldosterone transported in the blood?

Answer 15

60% protein bound

40% free form,

this accounts for its short half life of 20 minutes vs. other adrenocortical hormones (like cortisol)

Question 16

Where are adrenocortical hormones metabolized?

Answer 16

Metabolized in the liver

inactive conjugates excreted by the liver

Question 17

What would happen without mineralocorticoids?

Answer 17

Think: without aldosterone

Massive salt wasting and hyperkalemia

Question 18

Since cortisol has some mineralocorticoid effect, and there’s an enormous concentration of it floating in the plasma, why doesn’t it have a big effect on the kidneys?

Answer 18

renal epithelial cells express 11B-HSD2

prevents cortisol from activating mineralocorticoid receptors

Question 19

What is Apparent Mineralocorticoid Excess Syndrome?

Answer 19

AME

Happens when the 11b-HSD2 enzymes are deficient, allowing cortisol to bind to mineralocorticoid receptors

looks like hyperaldosteronism, but aldosterone levels are low

Question 20

What does Aldosterone impact: total sodium or sodium concentration?

Answer 20

TOTAL SODIUM!

Water moves with the sodium, and concentration remains the same

Question 21

What is aldosterone escape?

Answer 21

only elevates extracellular volume for about two days

As ECF increases, so does GFR

results in pressure natriuresis/diuresis whcih returns the renal output of sodium and water to normal despite excess aldosterone

Question 22

An increase in aldosterone does not effect sodium concentration, but a decrease does. Why?

Answer 22

Decreased aldosterone leads to massive water loss, which triggers ADH

ADH causes water reabsoprtion but NOT sodium reabsorption

You get a decrease in [Na]

Question 23

What are the most potent regulators of aldosterone secretion?

Answer 23

[K]

Angiotensin II

Question 24

95% of the glucocorticoid activity of the adrenal cortex results from the secretion of ________

Answer 24

cortisol/hydrocortisone

Question 25

What is gluconeogenesis?

Answer 25

formation of carbohydrates from proteins and other substances in the liver

Question 26

By what 3 modes does cortisol increase gluconeogenesis?

Answer 26

1. Activates liver cell DNA transcription to create enzymes required to convert amino acids into glucose 2. Moves amino acids from the muscles into the liver 3. Antagonizes insulin's inhibitory effect on gluconeogenesis

Question 27

Cortisol causes blood glucose to rise for two reasons:

Answer 27

1. gluconeogenesis 2. decreased glucose utilization by cells

Question 28

What is adrenal diabetes?

Answer 28

elevated cortisol cuases an increase in blood sugar, and in doing so decreases tissue sensitivity to insulin The pancreas is working just fine and releases an appropriate amount of insulin, but the tissues are resistant to insulin so the blood sugar remains elevated the problem isn't the pancreas, its the cortisol levels

Question 29

Cortisol reduces the amount of ____ protein, and increases the amount of ______ protein

Answer 29

cellular liver and plasma (wants to preserve amino acid consumption, so it reduces the ability of all nonhepatic cells to make proteins)

Question 30

How does cortisol mobilize amino acid transport to the liver?

Answer 30

It prevents anabolic processes, but it doesn't effect catabolic protein metabolism. This means cells aren't producing proteins, but they are still breaking them down. The excess amino acids released and transported via blood to the liver

Question 31

Cortisol _______ fatty acid mobilization

Answer 31

increases

Question 32

Why does excess cortisol cause obesity (moon face etc)?

Answer 32

not totally known excess stimulation of food intake is likely

Question 33

Any stress causes an increase in the secretion of ______ from the anterior pituitary, which causes secretion of cortisol

Answer 33

ACTH

Question 34

Cortisol has a preferrential on amino acid mobilization. Explain.

Answer 34

cortisol usually does not mobilize the basic functional proteins of the cell, such as muscle contracile proteins and proteins of neurons It will eventually mobilize these AAs, but not until all others have been used

Question 35

What are the five stages of inflammation?

Answer 35

1. Chemicals released from damaged tissue 2. increased blood flow to area causes erythema 3. capillary leakage followed by clotting of tissue fluid causes nonpitting edema 4. infiltration of leukocytes 5. fibrous tissue healing

Question 36

What are the five anti-inflammatory effects of coritsol?

Answer 36

1. Stabilizes lysosomal membrane, decreasing the amount of chemicals released 2. Decreases permeability of capillaries (2/2 decreased proteolytic lysosome release) 3. Decreased mediators means decreased WBC migration 4. lymphocytes are suppressed 5. reduces fever by preventing release of interluekin-1

Question 37

The anti-inflammatory effects of cortisol boil down to two global effects:

Answer 37

stabilizing lysosomal membranes reducing the formation of prostaglandins and leukotrienes from arachidonic acid in damaged cell membranes

Question 38

What effect does cortisol have on lymph tissue?

Answer 38

causes significant atrophy, which decreases the output of T cells and antibodies from the lymphoid tissue

Question 39

Describe the pathway for cortisol secretion:

Answer 39

1. Corticotropin-releasing factor is released from the hypothalamus 2. CRF triggers ACTH release from the anterior pituitary 3. ACTH triggers cortisol release from the adrenal cortex

Question 40

Describe the circadian rhythm of glucocorticoid secretion

Answer 40

the secretory rates of CRF, ACTH, and cortisol are high in the early morning and low in the late evening

Question 41

When are glucocorticoids released?

Answer 41

Under stress conditions

Question 42

Why do glucocorticoids decrease immune and inflammatory responses?

Answer 42

They decrease the natural killer cell activity Block the synthesis of prostaglandins, thromboxanes, and leukotrienes suppress the synthesis/secretion/action of chemical mediators (like histamine)

Question 43

What are some of the most problematic side effects of glucocorticoid administration?

Answer 43

infection poor wound healing

Question 44

The adrenal medull functions as a sympathetic \_\_\_\_\_\_

Answer 44

ganglion, without postganglionic processes

Question 45

Physiologic stress triggers release of adrenal catecholamines through \_\_\_\_\_\_\_\_

Answer 45

acetylcholine from preganglionic sympathetic fibers Depolarizes chromaffin cells depolarization sparks exocytosis of catecholamines

Question 46

Secretion of adrenal catecholamines is triggered by:

Answer 46

1. Sympathetic stimulation 2. ACTH 3. Glucocorticoids

Question 47

What is the prevalence of impaired glucose tolerance/diabetes in adults over 65?

Answer 47

40-50% Decline in beta cell function

Question 48

The decline of GH and IGF with age is referred to as:

Answer 48

somatopause leads to decreased muscle size and function

Question 49

Why is hyponatremia a common finding in the elderly?

Answer 49

Changes in renal function and sensitivity NOT due to changes in ADH