Renal system Flashcards
What is the basic function of the renal cortex?
Where filtration and bulk processing happens
kind of the outer bit of kidney
What body cavity do nephrons drain into?
Calyx
- gives unidirectional flow
- if blocked then have back flow of urine into the kidney
What is the difference between the long and short loop of henle?
Short: mainly in the cortex
Long: dips past cortex into medulla (means urine can be concentrated)
Where does the blood flow into the kidney?
Glomelular capillaries in the renal cortex
kidney is highest perfused organ in body (or second)
Describe the route of blood flow through the kidney starting with artery and ending with vein
Artery-> afferent arteriole -> glomerulus (filtration)-> efferent arteriole -> peritubular capillary -> venule -> vein
artery-arteroile-capillary-arteriole-capillary-vein
Which has cells that have adapted to a low O2 environment: Medulla or Cortex?
Medulla
pO2 ~ 10mmHg
Why is high blood flow so important in the kidney?
High blood flow NEEDED for glomerlular filtration rate NOT metobolic purposes
What exerts colloid oncotic pressure?
net oncotic= 25 mmHg
Proteins in the blood; they PULL fluid towards them
hence why colloid oncotic pressure= pulling pressure
Are proteins filtered in Bowmans space?
No, hence the colloid oncotic pressure= 0mmHg
What DECREASES GFR?
glomelular filtration rate
angiotensin II (ANGII)
noradrenalin
endothelium-1 (ET-1)
What INCREASES GFR?
glomerular filtration rate
Nitric oxide
Prostoglandins
Protein in your urine is a sign of what?
That your filtration barrier is breaking down
What are the three filtration layers separating plasma from bowmans space?
- capillary endothelium (lets in water but not proteins, neg charge)
- basement membrane (collagen matrix- densely negative)
- Podocytes (epithelium): fine mesh
What are normal sodium and potassium levels in renal epithelial cells?
20 mM Na
110 mM K
Have about 140mM Na and 5 mMK in the blood, so this creates driving forces
What molecule is recorded from urine to calculate GFR?
Inulin: bc its excreted at same rate as its filtered by glomerulus
Creatinine: in plasma and broken down from skeltal muscles over time
How much Na, K, water, bicarbonate, phosphate, glucose, and amino acids does the PCT reabsorb?
65% of Na, K, water, bicarbonate, phosphate
100% glucose and amino acids
can do this bc it has leaky epithelial cells
The AMOUNT of Na is LARGE but the concentration is the same = as plasma => because PCT has leaky epithelial cells so water moves with the Na
Should be NO amino acids or glucose in someones urine
What transporters are found in the PCT and what are their functions?
NHE3: Na import coupled with H+ export
AQP1: water import
NaPi2: brings in P with Na
SGLT2: brings in glucose with Na (dysfunctional in T2 diabetes)
NHE3 accounts for 1/2 of the sodium that the PCT reabsorbs
Why is the thick ascending limb of the loop of henle sometimes called the ‘diluting segment’?
Because there is NO WATER reabsorption
only cations can go through
water is impermeable bc NO aquaporins = NO transcellular pathway
What transporters are found in the TAL?
thick ascending limb= TAL
NKCC2: imports K+, 2 Cl-, Na
ROMK: exports K+ (to keep NKCC2 running) and generates +10 mV in the lumen which pushes cations into the cell
Doesnt import a LOT of K because if K wasnt recycled then NKCC2 wouldnt work (bc 5mM of K in the blood so not loads)
Means that NKC22 is ELECTROGENIC
Where is the paracellular cation shunt found?
What cations does it let through into the interstital fluid?
What osmotic gradient does it generate?
- TAL
- Na+, K+, Mg2+, Ca2+
- +200 mosmol
this is generated bc of ROMK, the +10 mV in the lumen drives the cations across the apical membrane between cells
Which part of the renal system do thiazide diuretics target?
The sodium transporter in the distal convoluted tube
Thiazide diuretics used to treat high BP
What are the two cell types found in collecting duct?
Principal cell: main cell type, Na/K
Intercalated cell: intercalates between principal cells; alpha (acid) and beta (base)
also has cilila (for sensing flow)
one collecting duct for every 10 nephrons
What transporters are found in the collecting duct?
NONE there are only CHANNELS found in the collecting duct:
ENac: imports Na
ROMK: exports K
ENac and ROMK create a -40mV in the lumen
What does aldosterone act on?
Retains sodium, loses potassium
* Acts on mineralcortocoid receptors in the principal cell in the collecting duct
* Essentially behaves like a TF and generates loads of ROMK, ENac, and NaK-ATPase — inc capacity for transport
retain Na and LOSE K