anatomy Flashcards
nephron: recall the constituent parts of a nephron and which compounds are absorbed in each area, explain the microscopic anatomy of the Bowman's capsule and list the regional features of tubular cells aiding urinary concentration, identify different sections and cell types of the nephron in light and electron microscopic images
what are 3 components of renal corpuscle
Bowman’s capsule, glomerulus consisting of capillaries, podocytes associated with glomerulus
where is the blood supply to in the renal corpuscle
vascular pole of corpuscle
where does blood enter in and exit from
afferent, then efferent, arterioles
how is blood filtered, including features which assist filtration
passes through glomerulus at high pressure from renal artery; high surface area, fenestrated capillaries, modified basement membrane, podocytes with feet which interdigitate
effect of hypertension on blood filtering in glomerulus
protein in urine
how is a pressure gradient created in glomerulus
afferent arteriole big, efferent arteriole small
what does the filtrate consist of
all components below 50000 RMM, keeping cells in bloodstream, so is isotonic
where is filtrate drained into proximal convoluted tubule
urinary pole of corpuscle
what % of glomerular filtrate are reabsorbed in proximal convoluted tubule
70%
5 materials reabsorbed by proximal convoluted tubule and brief method
Na+ uptake by basolateral Na+ pump, water and anions follow Na+, glucose uptake by Na+/glucose co-transporter, amino acid uptake by Na+/amino acid co-transporter, protein uptake by endocytosis (many vesicles)
type of proximal convoluted tubule epithelium
cuboidal
what is proximal convoluted tubule epithelium sealed with
fairly water-permeable tight junctions
why is there also not a huge influx/efflux of water at the proximal convoluted tubules
iso-molar filtrate
how is membrane area of proximal convoluted tubule increased to maximise rate of resorption
brush border at apical surface, interdigitations of lateral membrane
what does proximal convoluted tubule contain to allow some water diffusion
aquaporins
why do proximal convoluted tubule have prominent mitochondria
high energy requirement
what is the main function of loop of Henle and vasa recta blood vessels
creation of hyper-osmotic extracellular fluid
what is descending thin limb of loop of Henle made from
simple squamous epithelium
what do aquaporins in descending thin limb of loop of Henle allow
passive osmotic equilibrium
what are actively pumped out of tubular fluid in ascending thick limb of loop of Henle
Na+. Cl-
what is ascending thick limb of loop of Henle made from, and what does it have few of
cuboidal epithelium with few microvilli
how does ascending thick limb of loop of Henle have a very low water permeability
very water-impermeable tight junctions, membranes also lack aquaporins
what does a very low water permeability in ascending thick limb of loop of Henle result in
hypo-osmotic tubular fluid, hyper-osmotic ECF to allow movement of ions passively out of descending thin limb of loop of Henle
why are there prominent mitochondria in ascending thick limb of loop of Henle
high energy requirement
what type of mechanism is the loop of Henle and vasa recta
countercurrent
what are the vasa recta capillaries arranged in
loop
what is the blood in rapid equilibrium with
ECF
why is the vasa recta in a loop structure
stabilises hyper-osmotic [Na+]
features of distal convoluted tubules
no brush border; shorter length than proximal so fewer seen on slide; contain invaginations
what is distal convoluted tubule/cortical collecting duct made from
cuboidal epithelium with few microvilli
what does distal convoluted tubule use to adjust ions
hyper-osmotic ECF
what ions are controlled
Na+, K+, H+, NH4+
what do the complex lateral membrane interdigitations in distal convoluted tubule have
Na+ pumps
what hormone controls adjustment of ions, and subsequently blood pressure
aldosterone
what is present in numerour amounts and in a large size in distal convoluted tubule
mitochondria due to high energy demand
where does specialisation occur at in distal convoluted tubule
macula densa (part of juxtaglomerular apparatus)
what does the collecting duct have
many tight junctions
what are the 2 cellular components of juxtaglomerular apparatus
macula densa of distal convoluted tubule, juxtaglomerular cells of afferent arteriole
what specialisation is juxtaglomerular apparatus
endocrine (produces hormones)
what hormone does juxtaglomerular apparatus secrete and why
renin to control blood pressure via angiotensin
what can juxtaglomerular apparatus sense in arteriole wall
stretch
what can juxtaglomerular apparatus sense in tubule
[Cl-]
what does the fluid pass through with hyper-osmotic ECF
medulla
how is urine concentrated in medullary collecting duct
movement of water down osmotic gradient into ECF
what is rate of water movement dependent on in collecting duct
aquaporin-2 in apical membrane
how is content of urine varied
endo/exocytosis mechanisms
what is aquaporin-2 under control from
pituitary hormone vasopressin (ADH)
what does basolateral membrane of medullary collecting duct have
aquaporin-3, not under control of vasopressin (ADH)
what is the medullary collecting duct made from
simple cuboidal epithelium
do cell boundaries of medullary collecting duct interdigitate
no
why does medullary collecting duct have fewer mitochondria
little active pumping
how is blood pressure measured in kidney: high Na+
high Na+ in distal convoluted tubule stops renin release, stopping production of angiotensin I and II; vessels vasodilate and pass more urine; juxtaglomerular apparatus releases renin when signalled by macula densa (juxtaglomerular apparatus next to afferent arteriole)
how is blood pressure measured in kidney: low Na+
more renin so more aldosterone so more vasoconstriction which increases blood pressure
