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Flashcards in Physiology III Deck (25):

How does cortisol maintain blood pressure?

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


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

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)


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

Striae (p.292)


Describe the processes of cortisol regulation.

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)


How does chronic stress effect cortisol secretion?

Chronic stress induces prolonged cortisol secretion (p.292)


Where is PTH released from?

The chief cells of the parathyroid (p.293)


What are the four functions of PTH?

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)


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

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


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

It stimulates osteoclasts (p.293)


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

Increases PTH secretion (p.293)


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

Increases PTH secretion (p.293)


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

Decreases PTH secretion (p.293)


Name four common causes of decreased serum magnesium.

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


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

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


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

It increases it (p.293)


What two tissues does PTH effect when released into circulation?

Renal tubular cells; bone (p.293)


What are the four effects of PTH on bone?

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)


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

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)


What is the source of Vitamin D3?

Sun exposure in skin (p.294)


What is the source of Vitamin D2?

Ingested from plants (p.294)


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

In the liver (p.294)


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

In the kidney (p.294)


What is the active form of Vitamin D?

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


What are the two principle functions of vitamin D?

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


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

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