Lecture 23

Question 1

Give an overview of the function of the kidneys

Answer 1

Regulating the composition of most ECF/plasma ions
Maintaining water balance in the body
Helping maintain the proper acid-base balance of the body (blood pH)
Excreting metabolic waste
Producing: Erythropoietin (red blood cell production  oxygenation)
Converting vitamin D into its active form

Question 2

What is the difference between cortical and jutamedullary nephrons?

Answer 2

Cortical are more abundant but have shorter loops of Henle

The peritubular capillaries of the jutamedullary nephrons form hairpin loops called the vasa recta

Question 3

Describe the process of glomerular filtration

Answer 3

1. Afferent arteriole carries the blood (plasma) to the capillaries of the glomerulus
2. Pressure forces the plasma from capillaries into the bowman’s capsule (most of the proteins are removed by this filtration process)
3. Filtered plasma enters the proximal tubules
   Only 20% of plasma is filtered

Question 4

How much plasma is reabsorbed from that which is filtered?

Answer 4

123.75ml

Question 5

What are the transepithilial steps of reabsorption?

Answer 5

The substance first crosses the luminal membrane and then the cytosol.
It then crosses the basolateral membrane and then the interstitial fluid
Finally it passes through the capillary wall

Question 6

How much sodium is reabsorbed and where?

Answer 6

67% is proximal convoluted tubule
25% in ascending loop of Henle
8% in distal and collecting duct

Question 7

What controls arteriole blood pressure?

Answer 7

Renin-angiotensin-aldosterone system

Question 8

What is renin, where is it secreted and what does it do?

Answer 8

It is a hormone secreted by granular cells

It increases blood pressure