Wall Kidney Intro Flashcards
What is the Glomerulus?
Big ball of capillaries
What does the glomerulus make?
Plasma/glomerular ultrafiltrate…this filtrate is cell free and protein free.
What percent of total blood flow do the kidneys get?
10% per kidney….20% total
What do the Tubules do?
Reabsorption
Tubules reabsorb how much of the filtrate?
178 out of 180 liters. This is why we only make about 1-2 liters of urine a day
Best test of kidney function>
GFR
Where does glomerular filtration go?
Bowmans capsule
4 stages of renal function>
filtration, reabsorption, secretion, excretion
Outermost layer of kidney?
Renal Cortex
What percent of bloodflow does the renall cortex receive?
90% of the 10% directed to the kidneys.
What is inside the renal cortex?
The glomeruli (about 800k of them)
What is deep to the renal cortex?
Medulla
What is inside the medulla
tubular structures, loop of henle, collecting ducts, etc…
Deep to medulla?
Hilum- arteries, veins, ureter, nerves, lymph, all here.
What is a nephron?
Glomerulus and Tubular structure
Where are Cortical nephrons?
superficial
Besides cortical nephrons, what is the other kind of nephron?
Juxtamedullary nephron
Are cortical nephrons operating at 100%?
NEVER. we use reserve when we eat high protein meals.
What is the major function of the juxtamedullary nephrons
Urine concentration
What, besides urine concentration does the juxtamedullary nephron play a large role in?
Na transport.
What is the only source of blood supply to the medulla?
Vasa Recta
What does the vasa recta follow?
Loop of henle
What can be transferred between the ascending and descending medulla?
solute and oxygen
What is the glowerulus surrounded by?
Bowmans capsule
What the hell is an afferent arteriole?
Supplies pre-glomerular resistance
What the hell is the afferent arteriole?
supplies pre-glomerular resistance
What the hell is the efferent arteriole?
Post glomerular resistance
Describe the capillary wall of the glomeruli?
endothelial cells are the innermost layer, then glomerular basement membrane, then foot processes
Why the complexity of the capillary wall?
designed to keep in large proteins, mostly albumin…keeps it out of urinary space.
Are glomeruli perfused by higher or lower pressure than ordinary capillaries?
Higher
WHy higher pressure in the glomerulus?
In favor of filtration
Why are foot processes negatively charged?
Becuase, albumin is actually small enough that it COULD pass through the glomerular capillary wall. The negative charges repel it. Foot processes surround every glomerular capillary
What is a mesangium?
Provides skeletal structure to support the capillary loops
Are mesagnial cells contractile?
Yes, contain actin and myosin so that they can alter capillary surface area for filtration
WHy do mesangial cells have macrophage function?
To remove circulating immune complexes.
What layer(s) separate the mesangium from the circulation
only the endothelial layer
Podocytes?
Visceral epithelial cells (foot process) very negatively charged. ANy disease that results in proteinuria has a problem with this
What does the macula densa do?
Senses how much tubular fluid is reaching the macula densa. 90% of fluid reabsorbed before reaching macula densa/
What comes before the macula densa?
ALL tubular segments,,, thats why 90% of fluid is reabsorbed prior to reaching the MD.
After the macula densa?
Distal nephron segment for fine tuning homeostasis.
What is Tubular Glomerular feedback>
feedback from the the tubule to the glomerulus. If it senses too much delivery to the distal nephron, it changes the filtration rate.
Starling forces?
promote filtration, hydrostatic out of capilary.
This doesnt cover the formulas
or the last few pages of the presentation…look at that.
Define renal clearance
Volume of plasma cleared of a particular substance by elimination into the urine per unit time.
Renal clearance =
(Urine concentration of substance z)x Urine flow rate/ Plasma concentration of substance z
Best measure of GFR?
creatinine clearance
Clearance Ratio
Clearance of a particular
clearance ratio?
clearance rate of a substance over the GFR
What is clearance ration used for?
To tell us how the kidney handles a particular substance
Clearance ratio 1, less than 1, more than 1
1- creatinine, less= filtered then reabsorbed, more than= filtered and secreted
0= too large to be filtered or completely filtered and completely reabsorbed
About what percent of Renal Plasma Flow becomes glomerular filtrate?
20%
Volume Depletion (bleeding) leads to activation of what system
Renin Angiotensin
What is the key cell in reabsorption>
Renal epithelial cell
Two types of renal epithelial cell transporter?
Luminal, Basolateral
What separates luminal transporters from basolateral?
Tight junctions
Are there a bunch of Na out K in pumps on the basolateral surface? Luminal?
Basolateral- Yep
Luminal- No way. this would be counterproductive, you are trying to reomove Na from the filtrate and take it back into the cells, this would pump it out.
What is load dependent reabsorption?
The proximal tubule reabsorbs 50-55% of the filtered load even when GFR increases.
Fraction of filtrate reabsorbed stays the same always.
