4.Kidneys

Question 1

Anatomy of the kidney

Answer 1

Afferent arteriole, glomerulus, Efferent arteriole,

Glomerulus Loop of Henle, Peritubular Capillaries, Collecting Duct

Question 2

4 Steps of GFR?

Answer 2

1. Filtration
2. Reabsorption
3. Secretion
4. Excretion

Question 3

Normal GFR =

• Osmolarity ~

Answer 3

125 ml/ min / 1.73 m2

• Male ~ 7.5 L/h = 180 L/day!
• Female ~ 6 L/H = 144 L/day

300 mosmol/L = ECF

Question 4

Intrinsic mechanisms which control GFR include?

Answer 4

Tubulo Glomerular Feedback

Question 5

Extrinsic mechanisms which control GFR include the?

Answer 5

sympathetic nervous system

Question 6

Step 2: Reabsorption… lots of electrolytes + water

name the 2 steps in this

Answer 6

1. The filtrate passes along a tube equipped with aquaporins that are relatively impermeable to urea.
2. Salt and water are absorbed from the tube, leaving most of the urea behind with
   a small amount of remaining water

Question 7

Basolateral ATPase

Answer 7

3 Na+ to 2 K+

Question 8

• Cell: Low Na, high K,

__ mV potential

Answer 8

-70

Question 9

• Apical facilitated diffusion
– Gradient of Na ?
– Negative potential ______cell

Answer 9

– Gradient Na+ 140 mM vs 12 mM

– Negative potential inside cell

Question 10

The Na gradient is maintained by

Answer 10

the Na/K ATPase pump

Question 11

Na+ coupled glucose

symporter:

Answer 11

co-transport

Question 12

Secondary active reabsorption. How much

• Glucose?
• Na ?

Answer 12

• Glucose~ 5mmol/L

* Na ~ 140 mmol/L

Question 13

The end of the Proximal Tubule
_____fluid is ↓ from 6 L/h to approximately ~ 1.2 L/h.
i.e. best guess, 80% of ____is reabsorbed

Answer 13

Tubular

GFR

Question 14

The Na-K ATPase maintains a sodium gradient to enable ?

Answer 14

Na+ reabsorption

Question 15

what happens to [Na] concentration at the end of the Proximal Tubule?

Answer 15

No change in [Na] concentration

Question 16

There is no __________at end of the Proximal Tubule?

Answer 16

No glucose or amino acids

Question 17

The end of the Proximal Tubule ~iso-osmotic;

the missing osmoles are made up by?

Answer 17

the missing osmoles are made up by urea

Question 18

The end of the Proximal Tubule

Urea concentration is~

Answer 18

Urea concentration is ~ 2-4x higher than it was in the original glomerular filtrate (and ECF of course)