Session 2- Tubular Glomerular Feedback+ Reabsorption

Question 1

Name 2 adaptation of the glomerula capillaries that make it act as a filtration barrier?

Answer 1

Fenestrations and Podocytes (negatively charged)

Question 2

What are the pressures acting here?

Answer 2

Question 3

Outline the myogenic mechanism in the glomerulus?

Answer 3

When BP is high, afferent arterioles detect a stretch in vascular muscle wall. This causes the smooth muscle to contract in the afferent arteriole to reduced blood from and bring down GFR.

When BP is low, the smooth muscle in efferent arterioles contract creating a back flow in the glomerulus to bring up the GFR.

Question 4

Outline the tubuloglomerular feedback mechanism for a low BP?

Answer 4

3 Potential Stimuli:
Signals generated by Macula Densa Cells in response to low NaCl delivery.
Low stretch in the afferent arteriole
Sympathetic Nerve Stimulation

Response:
Prostaglandins are released that cause the constricted afferent arteriole to relax.
Renin is released by juxtaglomerular cells, this stimulated RAAS system. Angiotensin II constricts the efferent arteriole. Aldosterone stimulated greater sodium and in turn water absorption.

Question 5

Outline the tubuloglomerular feedback mechanism for a High BP?

Answer 5

Macula Densa cells of the Distal convoluted Tubule detect increased rate of NaCl delivery causing them to swell. A signal is sent via juxtaglomerular cells, ATP is released which is converted to adenosine. This binds to the A1 receptors of the afferent arteriole causing them to constrict. Renin is also inhibited.

Question 6

Label 1 to 4

Answer 6