GFR and filtration

Question 1

Name 4 functions of the kidney

Answer 1

Regulation, excretion, endocrine and metabolism

Question 2

Which 3 substances are completely recovered by the kidney?

Answer 2

glucose, amino acids and bicarbonate

Question 3

What is the average amount of urine produced per day?

Answer 3

1.5L

Question 4

What is the difference between osmolarity and osmolality?

Answer 4

Osmolarity = osmoles of solute per litre, Osmolality = solute per kg of solvent

Question 5

Define filtration factor

Answer 5

The proportion of fluid that reaches the kidney that is actually filtered (roughly 20%)

Question 6

What is the basement membrane of the bowman’s capsule?

Answer 6

Acelluar gelatinous layer of glycoproteins with a negative charge

Question 7

Name the biggest substance that can pass through the bowman’s capsule?

Answer 7

Inulin

Question 8

What is the purpose of a negatively charged basement membrane?

Answer 8

Prevents negatively charged proteins leaving the capillaries and entering the bowman’s capsule

Question 9

Which 3 pressures affect filtration?

Answer 9

Hydrostatic pressure of the capillary and bowman’s capsule, oncotic pressure difference between capillary and tubular lumen

Question 10

What happens to the afferent arterioles when blood pressure rises or falls?

Answer 10

BP rises = afferent arteriole constriction , BP falls = afferent arteriole dilation

Question 11

How does high levels of NaCl affect the afferent arteriole when GFR is high?

Answer 11

NaCl moves into the Macula Densa cells causing them to release ATP, converts to Adenosine, increases intracellular calcium, constriction of the afferent arteriole

Question 12

How does low levels of NaCl affect the afferent arteriole when GFR is low?

Answer 12

Macula Densa cells release prostaglandins causing vasodilation of the afferent arteiole