glomerular filtration

Question 1

what are the basic renal processes

Answer 1

filtration
reabsorption
secretion

Question 2

what is formed by filtration

Answer 2

formation at the glomerular capillaries of an essentially protein-free filtrate of plasma (~20%)

Question 3

reabsorption

Answer 3

substances body wants are absorbed

those it doesnt want stay in tubule and are excreted

Question 4

secretion

Answer 4

substances may be specifially removed from the body in this way

Question 5

normal glomerular filtration rate

Answer 5

125mls/min

Question 6

what is glomerular filtration dependant on

Answer 6

balance between hydrostatic forces favouring filtration and the oncotic pressure forces favouring reabsorption

Question 7

why is glomerular capillary pressure high

Answer 7

afferent arteriole is short and wide, offering little resistance to flow whilst efferent arteriole is long and narrow offering high post-capillary resistance

Question 8

golden rule of circulation

Answer 8

if you have high resistance, hydrostatic pressure upstream is increased while downstream pressure is decreased

Question 9

net filtration pressure

Answer 9

10mmHg

Question 10

what is GFR dependent on

Answer 10

on the afferent and efferent arteriolar dimater and so balace of resistance between them

Question 11

extrinsic control of afferent and efferent arterioles

Answer 11

sypathetic nerves: contriction (more so afferent)
catecholamines: afferent constriction
angiotensin II: effetrent when low, both when high

Question 12

intrinsic control afferent and efferent arterioles

Answer 12

autoregulation
adjust resistance in response to changes in BP

if BP in then inc in afferent arteriole constriction to prevent GFR rising