Glomerulus, GFR, clearance

Question 1

Describe the glomerulus and its function

Answer 1

Selective filtration barrier that filters blood based on size and charge of particles
No blood cells pass
Very little protein passes
Creation of ultrafiltrate:
- water
- electrolytes
- glucose

Question 2

What is GFR?

Answer 2

glomerular filtration rate = amount of fluid filtered from the glomerular capillaries into Bowman’s capsule per minute

Question 3

Describe the control of GFR?

Answer 3

GFR affected by Blood flow and hydrostatic pressure (controlled by arterial blood pressure and the resistance of the afferent and efferent arterioles)
Autoregulation:
- stretch receptors
- macular densa
Angiotensin II:
- via renin released from JGA
Neural regulation:
- SNS and PSNS

Question 4

What is renal clearance?

Answer 4

the volume of plasma cleared of a substance in a unit of time

Question 5

Why do we measure GFR?

Answer 5

GFR acts as an indirect measure of renal function

Question 6

How do we measure GFR?

Answer 6

Measuring substances that are freely filtered:
- Urea
- Creatinine
- insulin
- cystatin-C
- SDMA
- FGF-23
These will increase in blood when GFR is reduced

Question 7

What is nephrotic syndrome?

Answer 7

= combination of significant protein loss in the urine, high serum cholesterol and low serum albumin
Tissue oedema forms as a consequence of the low protein
glomerulonephritis => widespread inflammation