Filtration

Question 1

Renal clearance definition ___.

Renal clearance = ___*___/____

Answer 1

volume of plasma from which the substance is cleared per unit of time.
= (urine flow rate)*(urine concentration) /(plasma concentration)

Question 2

If clearance

Answer 2

net resorption of substance

Question 3

If clearance > GFR, net ___

Answer 3

net tubular secretion of substance

Question 4

If clearance = GFR ___

Answer 4

no net secretion or absorption

Question 5

GFR definition

Answer 5

is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman’s capsule per unit time

Question 6

___ is used to calculate GFR and why?

Answer 6

Insulin, because it is freely filtered and neither reabsorbed nor secreted. So for insulin clearance = GFR

Question 7

___ is an approximate measure of GFR, but it slightly overestimates GFR because ___

Answer 7

Creatinine clearance, but it slightly overestimates GFR because it is moderately secreted by renal tubules.

Question 8

Normal GFR is ~___, and ___ in GFR define stages of CKD.

Answer 8

100mL/min, reductions in GFR define stages of CKD.

Question 9

Effective renal plasma flow = eRPF can be estimated with ___ clearance because ___.

Answer 9

para-aminohippuric acid (PAH) clearance, because nearly all of the PAH is excreted

Question 10

eRPF ____ true renal plasma flow

Answer 10

underestimates

Question 11

Filtration fraction = FF = __/___. Normal FF is ___%

Answer 11

FF=GFR/RPF

Normal FF is 20%

Question 12

Afferent arteriole constriction causes GFR to __ and RPF to___ and FF to ___.

Answer 12

GFR decrease and RPF decrease and FF doesn’t change.

Question 13

Efferent arteriole constriction causes GFR to __ and RPF to___ and FF to ___.

Answer 13

GFR increase and RPF decrease and FF increase

Question 14

Increase in plasma protein concentration causes GFR to __ and RPF to___ and FF to ___.

Answer 14

GFR decrease RPF doesn’t change and FF decrease

Question 15

Constriction of ureter causes GFR to __ and RPF to___ and FF to ___.

Answer 15

GFR decrease RPF doesn’t change and FF decrease

Question 16

Dehydration causes GFR to __ and RPF to___ and FF to ___.

Answer 16

GFR decrease RPF decrease (due to increase viscosity) and FF increase

Question 17

Reabsorption = ___-___

Answer 17

filtered-excreted

Question 18

Secretion = __-___

Answer 18

excreted - filtered

Question 19

Glucose at normal plasma level is completely reabsorbed in ___ by ___.

Answer 19

Proximal convoluted tubule by Na+/glucose cotransport

Question 20

Proximal convoluted tubule reabsorbs all __ and __, as well as most:

Answer 20

All glucose and amino acids.

Most H2O, Na (60-80% reabsorbed), K, Cl, HCO3, PO4, uric acid.

Question 21

Proximal convoluted tubule generates and secretes ___ which does___

Answer 21

NH3 which acts as buffer for secreted H+

Question 22

Angiotensin II acts on ___ stimulates ___ which causes reabsorption of __

Answer 22

On PCT, stimulates Na/H+ exchange, causes reabsorption of Na, H2O, HCO3, causing contraction alkalosis

Question 23

Thick ascending loop of Henle reabsorbs:

Answer 23

Na (10-20%), K, Cl. Indirect reabsorption of Mg and Ca through +lumen potential caused by K backleak.

Question 24

Thin descending loop of Henle does this:

Answer 24

Concentrates urine by passively reabsorbing H2O via medullary hypertonicity (impermeable to Na)

Question 25

Distal convoluted tubule reabsorbs:

Answer 25

Na (5-10%), Cl, makes urine fully dilute (hypotonic)

Question 26

Collecting tubule reabsorbs __ in exchage for__, regulated by ___

Answer 26

Na reabsorbed in exchange for secreting K and H+, regulated by Aldosterone acting on mineralocorticoid receptor

Question 27

ADH acts on ___

Answer 27

Collecting tubule V2 receptors to reabsorb 3-5% of Na.

Question 28

Summary:
Angiotensin II acts on ___
Aldosterone acts on __
ADH acts on __

Answer 28

Angiotensin II acts on Proximal convoluted tubule
Aldosterone acts on Collecting tubule
ADH acts on Collecting tubule