Renal

Question 1

major functions of kidney

Answer 1

1. regulate water content, mineral composition, and pH
2. excrete end-products of metabolism
3. excretion of foreign chemicals
4. secrete hormones
5. glucogenesis

Question 2

Nephron

Answer 2

functional unit of kidney
consists of
- glomerulus and long tubule
- tuft of capillaries
- blood enters via afferent art and exits via eff art
- surrounded by Bowmans capsule

Question 3

flow through nephron

Answer 3

Bowman’s capsule - proximal tubule - loop of Henle - distal tubule - cortical collecting duct - medullary connecting duct - renal pelvis

Question 4

3 basic processes of kidney

Answer 4

1. filtration
2. reabsorption
3. secretion

Question 5

Filtration

Answer 5

glomerulus receives blood from aff art - increases pressure in glomerulus
- force resisted by colloid osmotic pressure and hydrostatic pressure of Bowman’s space

Question 6

glomerular capillary permeability

Answer 6

up to 500x greater than other capillaries
- endothelial cells perforated by “fenestrae”
- BM mesh-like

Question 7

protein make-up of kidney filtrate

Answer 7

only 0.3% protein

Question 8

plasma in glomerulus filtered into Bowman’s capsule

Answer 8

20%

Question 9

GFR

Answer 9

glomerular filtration rate - flow of plasma from glomerulus to bowman’s capsule

Question 10

normal GFR

Answer 10

apprx 125 mL/min
- decr GFR incr reabsorption
- incr GFR decr reabsorption

Question 11

autoregulation of GFR

Answer 11

1. afferent arteriolar vasodilator feedback
2. efferent arteriolar vasoconstriction feedback
   - happens at juxtaglomerular complex

Question 12

peritubular capillaries reabsorb

Answer 12

greater than 99% of water and most electrolytes

Question 13

movement of water dependent on Na+ transport

Answer 13

happens mostly at proximal tubule

Question 14

Na+ transport and reabsorption

Answer 14

1. Na+ diffuses from tubular lumin into epithelial cell - actively transport into interstitium by Na/K pump
2. water and Na+ move into capillary by bulk flow
3. pumps throughout tubular network
4. diffusion of water only if membr permeable

Question 15

luminal membrane most permeable

Answer 15

proximal tubule (not so tight junctions)

Question 16

Water reabsorption of network

Answer 16

proximal tubule - 65%
loop of Henle - 15%
distal tubule - 10%
collecting ducts - 9.3%
passing into urine - 0.7%

Question 17

water reabsorption at ducts regulated by

Answer 17

ADH

Question 18

ADH regulation

Answer 18

controls number of water channels in luminal membrane (incr ADH = incre permeability and incr reabsorption)

Question 19

ADH secretion controlled by

Answer 19

baroreceptors in aorta/carotid artery (incr pressure = decr ADH)
osmoreceptor in hypothalamus (decr osmolarity = decr ADH)

Question 20

hormonal regulation of Na+ reabsorption

Answer 20

aldosterone stim reabsorption of Na+ by collecting ducts by incr genetic expression of Na/K pumps and incr insertion of Na+ channels

Question 21

Renin-Angiotensin system

Answer 21

renin released by juxtaglomerular apparatus forms angiotensin 1 which turns to angiotensin II - stims aldosterone production

Question 22

Secretion

Answer 22

certain substr transported from interstitium into lumen of tubular network to be excreted in urine