Physiology III

Question 1

How does cortisol maintain blood pressure?

Answer 1

By upregulating alpha1 receptors on arterioles. This increases sensitivity to NE and Epi (p.292)

Question 2

What are the five ways that cortisol serves an anti-inflammatory/ immunosuppressive role?

Answer 2

1.) inhibits production of leukotrienes and prostaglandins; 2.) inhibits leukocyte adhesion (neutrophilia); 3.) blocks histamine release from mast cells; 4.) reduces eosinophils; 5.) blocks IL-2 production (p.292)

Question 3

What is the clinical manifestation of inhibition of fibroblasts by cortisol?

Answer 3

Striae (p.292)

Question 4

Describe the processes of cortisol regulation.

Answer 4

CRH from the hypothalamus acts on the anterior pituitary to cause ACTH release. ACTH release causes cortisol production and in the adrenal zona fasciculata. Excess cortisol decreases CRH, ACTH, and cortisol secretion (p.292)

Question 5

How does chronic stress effect cortisol secretion?

Answer 5

Chronic stress induces prolonged cortisol secretion (p.292)

Question 6

Where is PTH released from?

Answer 6

The chief cells of the parathyroid (p.293)

Question 7

What are the four functions of PTH?

Answer 7

1.) Increases bone resorption of calcium and phosphate; 2.) Increases kidney reabsorption of calcium in the distal convuluted tubule; 3.) decreases reabsorption of phosphate in the proximal convuluted tubule; 4.) increases 1,25 (OH)2D3 (calcitrol) production by stimulating kidney 1a hydroxylase (p.293)

Question 8

What effect does PTH have on serum calcium, serum phosphate, and urinary phosphate?

Answer 8

Increases serum Ca; decreases serum phosphate; increases urine phosphate (p.293)

Question 9

What is the effect of increased production of M-CSF and RANK-L in osteoblasts?

Answer 9

It stimulates osteoclasts (p.293)

Question 10

What effect does decreased serum calcium concentration have on PTH release?

Answer 10

Increases PTH secretion (p.293)

Question 11

What effect does mildly decreased serum magnesium concentration have on PTH release?

Answer 11

Increases PTH secretion (p.293)

Question 12

What effect does significantly decreased serum magnesium concentration have on PTH release?

Answer 12

Decreases PTH secretion (p.293)

Question 13

Name four common causes of decreased serum magnesium.

Answer 13

Diarrhea; aminoglycosides; diuretics; alcohol abuse (p.293)

Question 14

What two factors cause feedback inhibition on PTH release from the parathyroid glands?

Answer 14

Increased production of 1,25-(OH)2D3 from the kidney and increased serum calcium (p.293)

Question 15

What effect does production of 1,25-(OH)2D3 have on intestinal calcium absorption?

Answer 15

It increases it (p.293)

Question 16

What two tissues does PTH effect when released into circulation?

Answer 16

Renal tubular cells; bone (p.293)

Question 17

What are the four effects of PTH on bone?

Answer 17

1.) stimulates Ca2+ release from bone mineral compartments; 2.) stimulates osteoblastic cells; 3.) stimulates bone resorption via indirect effect on osteoclasts; 4.) enhances bone matrix degradation. These four processes act to increase serum Ca2+ (p.293)

Question 18

Describe the physiological adaptations that occur when serum phosphorous becomes low.

Answer 18

Low serum phosphorous increases conversion of 25-(OH)D3 –> 1,25-(OH)2D3 in the kidney. This acts to stimulate bone to release phosphate from matrix and acts on the intestine to increase phosphate reabsorption (p.293)

Question 19

What is the source of Vitamin D3?

Answer 19

Sun exposure in skin (p.294)

Question 20

What is the source of Vitamin D2?

Answer 20

Ingested from plants (p.294)

Question 21

Where are vitamins D3 and D2 converted to 25-OH?

Answer 21

In the liver (p.294)

Question 22

Where are vitamins D3 and D2 converted to their active form?

Answer 22

In the kidney (p.294)

Question 23

What is the active form of Vitamin D?

Answer 23

1,25-(OH)2 (p.294)

Question 24

What are the two principle functions of vitamin D?

Answer 24

To increase absorption of dietary Ca2+ and phosphate; to increase bone resorption of Ca2+ and PO43- (p.294)

Question 25

What causes increased production of 1,25-(OH)2?

Answer 25

Increased PTH, decreased Ca2+, and decreased phosphate (p.294)