Glomerular Function

Question 1

Describe the renal blood flow

Answer 1

1. Renal artery
2. Segmental arteries
3. Interlobar arteries
4. Arcuate arteries
5. Interlobular arteries
6. Afferent arterioles
7. Glomerular capillaries
8. Efferent arterioles
9. Peritubular capillaries
10. Interlobular veins
11. Arcuate veins
12. Interlobar veins
13. Renal vein

Question 2

What are the factors determining GFR?

Answer 2

1. Balance of hydrostatic and colloid osmotic forces acting across the capillary membrane
2. The capillary filtration coefficient (Kf)

Question 3

What is Kf?

Answer 3

• GFR/NFP

- Determined by the product of permeability and surface area of the capillaries for filtration

Question 4

What are the membrane layers of the glomerular capillary?

Answer 4

1. endothelium of the capillary
2. basement membrane
3. layer of podocytes

Question 5

What are the layers of Bowman’s capsule?

Answer 5

• Inner visceral layer

- Outer parietal layer

Question 6

Define nephron

Answer 6

Structural and functional unit of kidney

Question 7

What is juxtaglomerular apparatus?

Answer 7

A specialized organ situated near the glomerulus of each nephron

Question 8

What is the normal urinary output?

Answer 8

1 to 1.5L/day

Question 9

What is the role of renin in the body?

Answer 9

• Converts inactive angiotensinogen into Angiotensin I

- Angiotensin I is converted to Angiotensin II by the converting enzyme

Question 10

What are the factors which stimulate secretion of renin?

Answer 10

• Decreased arterial blood pressure
• Reduction in ECF volume
• Increased sympathetic activity
• Decreased load of sodium and chloride in macula densa

Question 11

What are the normal values of GFR?

Answer 11

125 mL/minute or 180 L/day

Question 12

Define glomerular filtration rate

Answer 12

The total amount of filtrate formed in the nephrons of both the kidneys per unit time

Question 13

What is the normal filtration fraction?

Answer 13

15 - 20%

Question 14

Name the pressures, which determine the GFR

Answer 14

• Glomerular capillary pressure (60 mmHg)
• Colloidal osmotic pressure in the glomeruli (25 mmHg)
• Hydrostatic pressure in the Bowman’s capsule (15 mmHg)

Question 15

Name the processes involved in urine formation

Answer 15

1. Glomerular filtration
2. Tubular reabsorption
3. Tubular secretion of excretion

Question 16

What is macula densa?

Answer 16

• part of the DCT near the afferent arteriole, which is formed by tightly packed cuboidal epithelial cells