Renal Physiology - LW

Question 1

What are the Hormonogenesis functions of the Kidney?

Answer 1

1) Renin → BP control via regulation of fluid volume
2) Erythropoietin → increases oxygen carrying capacity via ↑ RBC
3) Vitamin D3 activation → converts vitamin to its active form D2

Question 2

What are the two types of Nephrons based on location within the Kidney?

Answer 2

• Cortical Nephrons (85%) → short loops

- Juxtamedullary Nephrons (15%) → very long loops, maintian salt gradient and conserve water

Question 3

What are the components of the Juxtaglomerular Apparatus and what is their function?

Answer 3

1) Juxtaglomerular Cells: smooth muscle cells mofified to form cuff around arteriole, mechanoreceptors that directly sense BP and release renin
2) Macula densa: tall, closely packed epithelial cells, senses changes in solute content and stimulates JGA

Question 4

What is the equation for Net Filtration Pressure?

Answer 4

NFP = BHP - (COP + CP)

Question 5

What is the amount of filtrate formed by the kidneys in one minute?

Answer 5

Adults → 100 to 125 ml/min (7.5L/Hour or 180 L/day)

Question 6

What factors determine filtration rate at capillary beds?

Answer 6

Net Filtration Pressure (NFP)
Total Surface Area
Membrane Permeability
Blood Flow

Question 7

At what point is autoregulation of Arterial Pressure absent?

Answer 7

At a mean arterial pressure less than 70 mm Hg

Question 8

What does the result of renin result in and what effect does renin have on the efferent arteriole and GFR?

Answer 8

• Potent vasoconstrictor of efferent arterioles at low concentrations
• Increases glomerular hydrostatic pressure and returns GFR to normal

Question 9

What are the hormones that cause vasoconstriction, thereby decreasing renal blood flow and GFR?

Answer 9

• EPI
• NorEPI
• Angiotensin II

Question 10

What are the hormones that cause vasodilation and increase renal blood flow and GFR?

Answer 10

-Prostaglandins PGE-2 and PGI-2 (prostacyclin)

Question 11

What are the physiological effects of Atrial Natriuretic Peptide (ANP)?

Answer 11

• ↑ GFR via constriction of efferent & dilation of afferent arteriole
• Natriuresis
• Inhibition of Aldosterone secretion
• Inhibition of Renin Secretion via ↑ Na+ delivery to macula densa

Question 12

What is the glucose transport maximum at the PCT?

Answer 12

TM = 320 mg/min

If blood glucose is > 220 mg/dL then some remains in urine

Question 13

What is the effect of ADH?

Answer 13

1) Helps maintain normal blood volume and BP.
2) Allows kidneys to produce urine which is more concentrated than body fluids.
3) Prevents excess water loss while still excreting all substances that must be eliminated.

Question 14

When is Aldosterone secreted and what are its effects?

Answer 14

• Secreted in response to ↑ K+ and ↓Na+ blood levels, and ↓ BP
• ↑ active transport of Na+ & Cl-, stimulates reabsorption of Na+ and secretion of K+