Glomerular Filtration and Urine formation Flashcards
what is the 2 types of nephrons and what is the main differences
- Juxtamedullary nephrons:
- proximal and distal convoluted tubules in cortex
- loop of henle runs deep into medulla
- capillary supplies: VASA RECTA - Cortical nephrons (abundant 80%)
- proximal and distal convoluted tubules in cortex
- loop of henle remains WITHIN cortex
- capillary supplies: PERITUBULAR capillaries
describe the flow of filtrate from the nephrons to ureter
- filtered and reabsorped by the kidney tubules in = Pyramid (medulla)
- enters renal papilla
- enters minor calyx
- enters major calyx (several minor = major)
- enters renal pelvis, then into ureter
describe the arterial blood flow of kidneys
- Aorta branches => renal artery (enters hilum)
- branches into INTERLOBAR arteries = runs in between renal pyramids
- branches into ARCUATE artery (at the base of the pyramid)
- Arcuate arteries branch into INTERLOBULAR arteries then into AFFERENT ARTERIOLE then into glomerulus
describe the venous blood flow
- glomerulus - exit via efferent arteriole - then into venous end of capillary bed
- interlobular veins
- enters arcuate vein
- enters interlobar veins
- renal veins (left and right, left is longer as has to pass to right side)
- both drains into inferior vena cava
name the 2 capillary beds
vasa recta and peritubular capillaries
what makes up the renal corpuscle
how many layers are there in bowmans capsule
what other cell type makes up the glomerulus
- bowmans capsule
- glomerulus
2 layers in bowmans capsule = parietal, visceral layer (includes podocytes)
mesangial cell also makes up the glomerulus = contractility present = regulate blood flow and integrity
what makes up the renal corpuscle filtration barrier
and size of the filtrate allowed through
- fenestrated endothelial lining of the glomeruli (but continuous basement membrane) - up to 100 nm
- the fused basal lamina of the endothelial cells AND podocytes = glomerular basement membrane (very negative, repels -ve charge species)
- Filtration slits - are formed between the foot processes of the podocytes (20-30 nm)
= no blood cells or cells through
= no proteins through
only soluble substances and small MW substances
what are the 1. filtration force 2. absorptive force
- filtration force: glomeruli capillary hydrostatic pressure:
> wide afferent arteriole, narro efferent arteriole = more in, less out = high pressure - absorptive force: glomeruli ONCOTIC PRESSURE (protein) and interstitial space hydrostatic pressure (aka within bowmans capsule)
what is the GFR and the classes of renal failure
normal GFR: 90-140ml/min
definition: volume of filtrate produced in BOTH KIDNEYS per minute
Stage 1: 90ml/min: structural changes present (histology), proteinuria etc
stage 2: 60-59ml/min
stage 3: 30-59ml/min
stage 4: 15-29ml/min
complete failure: less than 15 = transplant or dialysis
renal clearance definition and how to connect it with GFR
glucose and inulin values
RC: volume of blood that is cleared of a particular substance per minute
ie if 90ml/min = RC, then 90ml of blood is cleared of the substance per minute
RC can be used to estimate GFR when a substance is neither secreted (actively) nor reabsorbed
Glucose clearance: should be 0ml/min (all reabsorbed)
inulin = hard to measure not practical = creatinine (eGFR)
what is the equation of RC
RC = amount (not concentration) in urine/ concentration of the substance in blood
describe the process of ADH synthesis and release
- osmolality sensing: aka solute concentration
- osmoreceptor senses hyperosmolality = sends signal to neurosecretary cells
- neurosecretory cell: SON (supraoptic nucleus neuron) PVN (paraventricular nucleus neuron)
> synthesis ATP, delivers to axon terminal located at POSTERIOR pituitary gland
3.depolarisation of axon, opening of L-type Ca channel = exocytosis - into FENESTRATED endothelium
AQUAPORIN 2 insertion into the LUMINAL side of collecting duct
