Kidneys

Question 1

% of CO kidneys receive

Answer 1

20-25%

Question 2

how much fluid do the kidneys prod?

Answer 2

1200ml/min

Question 3

primary/secondary functions of kidney

Answer 3

1o → regulate vol and composition of body fluids

2o → syn vit D, BP reg, EPO syn, BGL reg

Question 4

% of nephrons in cortex

Answer 4

80-85%

Question 5

glomerulus capillary divisions

Answer 5

capillary divisions of renal A → glomerular capillaries → efferent arterioles → vasa recta → drains into venules → renal vein → IVC

Question 6

what is GFR dependent on?

Answer 6

• net filtration pressure
• total surface area
• filtration membrane permeability

Question 7

PCT reabs

Answer 7

contains brush border

reabs:
- 2/3 filtered Na and h2o
- ALL glucose and AA
- fraction of bicarbonate, k, p ,ca

Question 8

PCT secretion

Answer 8

NH3 (buffer for H+)

creatinine

Question 9

LoH descending limb

Answer 9

thin

• reabs h2o
• impermeable to Na → concentrates urine (Hypertonic)

Question 10

LoH ascending limb

Answer 10

thick

• na, k, cl actively reabs
• impermeable to h2o → less concentrated urine

Question 11

DT reabs

Answer 11

• na (less than PCT) ACTIVELY
• relatively impermeable to h2o → dec concentration
• regulated by hormones

Question 12

Collecting duct - principal cells

Answer 12

• reabs na + h2o
• secretes k
• regulated by ADH and aldosterone

Question 13

Collecting duct - intercalated cells

Answer 13

• reabs K ACTIVELY

- secretes H

Question 14

ADH

Answer 14

secreted by POS pit

- inc permeability to H2o (inc reabs) → concentrates urine

Question 15

ANH

Answer 15

secreted by atria of heart

- inc natriuresis (secretion of Na)

Question 16

aldosterone

Answer 16

• inc ACTIVE reabs of na AND secretion K (leads to hypokalemia)

Question 17

spironolactone

Answer 17

• inhibit na reabs in DT
• blocks Na channels and aldosterone release
• leads to Na excretion and K retention

Question 18

flow of urine fromkidneys

Answer 18

papilla → minor calyx → major → renal pelvis → ureter → bladder…

Question 19

how do ureters enter bladder

Answer 19

oblique entrance

- prevents vesicoureteral reflux

Question 20

what is the capacity of the bladder

Answer 20

300-500ml

Question 21

micturition reflex

Answer 21

bladder fills ~200-300ml → stretch wall → stretch R → micturition centers → PNS

• PNS stimulates detrusor contraction & internal urinary sphincter relaxation (invol)
• external urinary sphincter VOLUNTARY relax

Question 22

autoregulation of GFR

Answer 22

1) macula densa in DT sense dec GFR
2) JGC (granular cells) in afferent arteriole secrete renin
3) renin → angiotensinogen → ANG 1 → 2 → VC afferent tubules → inc GFR

Question 23

composition of urine

Answer 23

water = 95%
solutes (urea, uric acid, creatinine) = 5%

pH~6

Question 24

main issue with renal system in childhood to middle age

Answer 24

associated with infections

Question 25

GFR at birth → 2yrs

Answer 25

lower

Question 26

ageing and renal system

Answer 26

• dec function →dec size, nephrons, tubular cells efficiency
• dec renal BF (~10%/decade)
• inc glomerular basement membrane permeability → inc urinary excretion of proteins
• changes of response to vasoactive mediators (inc VC stim, dec VD stim)