RBF & GFR - Rao

Question 1

Hydrostatic and oncotic pressure in the glomerulus?

Answer 1

Hydrostatic high; oncotic lower but goes up

Question 2

In which arteries does hydrostatic pressure drop occur?

Answer 2

Afferent arteriole, efferent arteriole

Question 3

In which arteries does oncotic pressure go up?

Answer 3

Glomerulus

Question 4

What is an example of a substance that is freely filtered and neither reabsorbed or secreted?

Answer 4

Inulin

Question 5

What is an example of a substance that is freely filtered, partly reabsorbed, and not secreted?

Answer 5

urea

Question 6

What is an example of a substance that is freely filtered, not reabsorbed, but secreted from tubules?

Answer 6

Creatinine

Question 7

What is an example of a substance that is freely filtered but completely reabsorbed?

Answer 7

Glucose

Question 8

What is the difference in ion concentration between plasma and filtrate?

Answer 8

Filtrate has 5% more anions and 5% less cations

Question 9

What is a normal GFR?

Answer 9

120-130ml/min

Question 10

What is filtration fraction?

Answer 10

GFR/RPF, or basically the fraction of kidney blood supply that is filtered through glomeruli per minute

Question 11

What would ureteral obstruction do to GFR and FF?

Answer 11

Reduce

Question 12

What would renal artery stenosis do to RPF and FF?

Answer 12

Reduce RPF, increase FF

Question 13

What is Kf?

Answer 13

Filtration coefficient

Kf=Hydraulic conductivity*SA of glomerulus capillary

Measures capillary permeability to solutes

Much much higher in glomerulus than anywhere else

Question 14

What happens to Kf during DM?

Answer 14

Reduced bc of thickening of basement membrane and capillary damage

Question 15

Which two forces favor filtration?

Answer 15

Glomerulus hydrostatic and Bowman’s space oncotic pressure

Question 16

Which two forces oppose filtration?

Answer 16

Glomerulus oncotic pressure and Bowman’s space hydrostatic pressure

Question 17

What is a normal Kf?

Answer 17

.08

Question 18

How does capillary oncotic pressure change during slow plasma flow/change in protein concentration in glomerulus?

Answer 18

Low capillary flow causes increased filtration fraction, leading to increased glomerular oncotic pressure, then lower net filtration pressure and lower GFR

Question 19

The kidney autoregulates GFR by controlling this variable tightly

Answer 19

RPF

Question 20

How is RPF controlled?

Answer 20

Changes in relative vascular resistance

Question 21

What are the two major ways to autoregulate?

Answer 21

Myogenic - direct arteriolar smooth muscle stimulation

Tubuloglomerular feedback via juxtaglomerular complex monitoring

Question 22

What does the macula densa do when it senses high NaCl?

Answer 22

Increase afferent resistance to lower GFR

Question 23

What does the macula densa do when it senses low NaCl?

Answer 23

Decrease afferent resistance to raise GFR

Question 24

Explain the renin-angiotensin system

Answer 24

A reduction in arterial pressure or EC fluid volume lowers the glomerular hydrostatic pressure and GFR. MD senses the reduced Cl- since filtration has slowed, and the juxtaglomerular cells of MD secrete renin. Renin activates angiotensin I from a2-globulin, which in turn activates angiotensin II. ATII causes aldosterone release from the adrenal cortex, resulting in increased sodium and water retention.

Question 25

How does adrenaline affect the glomerulus?

Answer 25

Adrenaline causes afferent arteriolar constriction, reducing GFR. Useful in times of very low fluid volume.

Question 26

How does endothelin affect the glomerulus?

Answer 26

Damaged endothelium secretes it. It causes afferent AND efferent constriction, reducing GFR.

Question 27

How do NO and prostaglandins affect the glomerulus?

Answer 27

Decrease vascular resistance, increasing the GFR.

Question 28

How does the sympathetic nervous system influence the GFR?

Answer 28

Sympathetic nerves constrict afferent arterioles, reducing RPF and Pg. That lowers GFR, in turn stimulating renin secretion and increasing Na reabsorption. So the SNS and the renin-angiotensin system work together.

Question 29

Describe nephritic syndrome

Answer 29

Albumin and cells in urine

Dysfunctional podocytes

Question 30

Describe nephrotic syndrome

Answer 30

Albumin but NOT cells in urine

Wide slit pores