Renal physiology Flashcards
Arterial supply to kidney, subdivisions
Percentage of cardiac output at rest
Renal arteries, each dividing into 2 upper branches (supplying anterior and posterior upper poles) and lower branch (supplying lower pole). Then divide into interlobar, arcuate arteries interlobular arteries then afferent arterioles
Take 20% of resting Co
Blood vessels in kidneys distal to afferent arterioles
Glomerular capillaries
Efferent arterioles
Peritubular capillaries
Interlobular veins
Arcuate veins
Interlobar veins
Renal veins
Nervous supply to kidney
Autonomic T10-L1- travel with renal vessels
Some parasympathetic from vagus nerve
Nociceptive afferents T10-11
Layers of kidney external to internal
Capsule
Cortex
Medulla
Pelvis
Anatomy of a nephron
Knot of capiliaries from the afferent arteriole - glomerulus
Blind end of tubular system enveloping it - bowman’s capsule
Proximal tubule
Loop of Henle
Distal tubule
Collecting duct
Where in the kidney are nephrons found
Cortex with slight loop into medulla
25% have loop of henle that runs deep into medulla
Overall function of glomerulus
Produce an ultrafiltrate of plasma
What composes the glomerular filtration barrier
Fenestrated capillary endothelium
Glomerular basement membrane
Visceral epithelial cells of bowman’s capsule (podocytes)
Size of fenestrations in glomerular endothelium, function
60nm
Prevention of blood cells from contacting main filter
Main part of the glomerular filter?
Physiology and function
Basement membrane
Collagen and glycoproteins with strong negative charge
Allows passage of molecules according to size shape and charge
Anatomy and function of podocytes at bowman’s capsule
Encircling trabeculae with small processes (pedicels)
Pores between pedicels
Maintains basement membrane integrity and filtration selectivity
What is the composition of ultrafiltrate in the kidneys
What sizes of molecules included / excluded
Similar to plasma
Free of cells
Free of particles >70000 daltons
Reduced concentration of particles 7000-70000 daltons based on size and negative charge.
Particles <7000 pass through freely.
Term for nephrons that just pass into medulla
Term for nephrons that run deep into medulla
Cortical nephron
Juxtamedullary nephron
Where do collecting ducts drain
Renal papilla and calyces in medulla
Then into renal pelvis and on into ureter
Definition of stage 1 AKI
Cr increase of 26.4 micromol/L or by 150-200%
Urine output <0.5ml/kg/hr for >6hrs
Definition of stage 2 aki
Cr increase by 200-300%
Urine output <0.5ml/kg/hr for >12hrs
Definition of stage 3 AKI
Cr increase by 354.4 micro moles/L or by >300%
Urine output <0.3ml/kg/hr for >24hrs or anuric for 12hrs
GFR associated with each stage of CKD
1 >90
2 60-89
3 30-59
4 15-30
5 <15
Usual Glomerular filtration rate per day and per minute in L
180 L per day
Around 125 ml/min
What determins glomerular filtration
Size of molecules
Charge of basement membrane
Hydrostatic pressure gradient
Renal plasma flow
Colloid osmotic pressure gradient
Glomerular capillary coefficient
Blood pressure
Molecular weight of albumin
69000 daltons
What is the glomerular capillary coefficient
Value
Measure of resistance to flow of ultrafiltrate across the total glomerular surface
12.5ml/min/mmHg
What is the glomerular colloid osmotic pressure gradient
Glomerular capillary osmotic pressure - bowman’s capsule osmotic pressure
32 - 0
32mmHg
What determins colloid osmotic pressure in the glomerular capillaries
Colloid osmotic pressure in afferent arteriole
Filtration fraction
Renal plasma flow
Because as more fluid is filtered osmotic pressure will rise relatively