GFR and filtration Flashcards
Label
where does the afferent arteriole come from?
interlobular
what does the efferent arteriole drain into?
describe order of blood flow from Aorta ending at IVC
peritubular capillaries
label
what r the 2 types of nephrons we have and how do they differ?
which one is more abundant?
difference btw peritubular capillaries and vasa recta?
efferent A in CORTICOL NEPHRON>> Goes to form peritubular capillary
efferent A in Juxtameduallry NEPHRON>> Goes to form vasa recta
what is Renal plasma flow
what is filtration fraction,
600ml
which part of the kidney is the glomerulus found?
what is filtration fraction
cortex only!
_______% blood arriving exits via efferent arteriole (unfiltered)
80
how much GFR?
120-125 ml/min
what is the Renal corpuscle ?
what 2 things makes up the filtration barrier?
Describe the 3 layers
capillary endothelium and visceral layer of Bowman’s capsule
all these 3 have a negative charge! & protein have a fixed - charge, causing them to repel!
in some kidney diseases, this negative charge on the filtration barrier is lost!
how can this be a problamo?
proteins are more readily filtered - a condition called proteinuria
describe the effeect of charge
graph in lecture!
name the Physical forces involved in the filtering of plasma to form ultra filtrate
oncotic pressure in the glomerulus is telling the hydrostic p. in the capsule>>> please dont leave me, i’ve got all the proteins come to meee pleaseee
(so it opposing filtration)
describe the hydtostatic oressure of the glomerulus, why does it remain high across the entire capillar bed?
bc the glomerular capillaries r drained by a high-resistance efferent arteriole who resistence is smaller than the afferent that feeds them
describe Renal Autoregulation what is its purpose
the relative consistency of GFR and renal BF
to maintain a reletevly constant GFR!
total plamsa is only about 3 liters! any change in renal excretion can quikcly deplete it!
how is Renal autoregulation mediated?
2 mechanisms:
faster myogenic response
slower tubuloglomerular (TG) feedback system.
describe the myogenic mechanism
to what vessels does this apply to?
how quick is it?
ability of blood vessels to resist stretching during increased BP
super quick! (3-10s)
It is a property predominantly of the preglomerular resistance vessels
– accurate
– interlobular
– Afferent arteriole
thinking about afferent and efferent…
how can we decrease GFR (2 ways)
how can we increase GFR (2 ways)
BUT BE AWARE… effect of EFFERENT arterioles depends on the severity of the constriction…explain
if we increase the efferent resistence slightly> the hydosta. p will increase & GFR increase
BUTT
if they r severly constrcited! this can block renal BF! casuing proetin concentration to increase, and opppsoing forces increase, GFR decrease!
Autoregulation is able to maintain GFR when blood pressure is within physiological limits (80-180 mmHg)
describe the mechanism of tubular Glomerular Feedback!
This mechanism links Na+ and Cl- concentration at the macula densa with control of renal arteriolar resistance
It has 2 components
- Afferent arteriole mechaniam
- Efferent arteriolar mechanism
these depend on the anaotmical arrangments of the juxtamedullary cells
what is the juxtameduallry complex
consists of:
- Macular Densa on distal tubule
- jusxtamedullary cells in walls of aff and eff arterioles.
Macula densa contains golgo since its needs to send scretery organlles towards the arterioles!
what do the macula densa sense? what recpeter do they work by?
changes in blood volume!
it works via the Na/k/2Cl cotransporter in the apical membrane
and its via this transporter where it can detect a change in Cl-
what sorts of chemicals does the jusxtameduallry apparatus release?
to increase GFR
reducd GFR
To increase GFR >> Prostaglandins >>vasodilator of AA
Reduce GFR>> Adenosine >>
mainlyyyy works through A1 recepter on affer>> causes constriction
and A2 on efferent >> dilation
how does NSAIDS have an effect on the the bp?
NSAIDS inhbit prostaglandins
no dilation of afferent
decreased GFR
Decrease Bp
BUT THESE R ALL ACUTE MECHANISM!
Neural regulation of GFR
- Sympathetic nerve fibres innervate AE and EA
- Fight or Flight Or ischaemia Or haemorrhage (sever) can stimulate renal vessels
- Vasoconstriction occurs as a result which conserves BV (haemorrhage) and can cause a fall in GFR
if Na CL was _____at macula densa, this causes _____of afferent Arterioles!
whic areteriole is highly sensitive to ANg 2
EFFERENT
1st line of defence Myogenic and TG feedback
what comes next?
2nd line of defence
Glomerulotubular Balance blunts sodium excretion response to any GFR changes which do occur despite 1st line reposnses
