Kidney Normal Stuff Flashcards
Anatomy Review
Arcuate Artery is the boundary between?
Off arcuate artery is
KIdney has ___ artery that branches into__
Afferent wider diameter than
Anatomy Review
Arcuate artery is the boundary between cortex and medulla
interlobular artery which gives afferent arterioles
efferent artery, difference in diameter increases blood pressure to help force blood out through glomeruli
efferent, helps with above stuff
Pee path
Force fluid out capillariess into bowmans capsule
Urine filtrate to PCT (reabsorb/secretion), down into descening limb/ up ascending limb (modify conc of urine), DCT (back b/w afferent/efferent arterioles) at this point we have macula densa and JG apparatus (renin comes from here)
DCT join to collecting ducts, down to bladder
Descending limb of loop
Vs
Ascending Limb of loop
permeability
permeable to water, imp to salt
Ascending impermeable to water, active pump sodium out
DCT/colecting duct reabsorbtion/absortbtion is controlled by what biological mechanism?
HORMONAL
Absorbtion vs Reabsorbtion
Absorption
bring diff types of nutrients into blood stream.
Reabsorption
nutrients moving from urine filtrate back into blood stream
Both happen the same way
same processes drive both
Entire plasma volume is filtered but what percent is excreted as urine?
1%
3 steps of kidney
Golmerular filtration
force fluid/nutrients out of
blood into nephron
Reabsorb
everything good
Secretion
sub that dont get filtered
get forced into urine
filtrate
What is the cause/mechanism behind glomerular filtration?
Glomerular filtration is caused by the pressure difference between the afferent and efferent arterioles. The afferent arterioles have a larger diameter so the size difference increases blood pressure, forces liquid out into bowman capsule
When does tubular reabsorbtion/secretion
PCT
DCT/collecting ducts
changing concentration
GLOMERULAR FILTRATION:
Passive or active?
What powers it?
What is net filtration pressure (NFP)
Why glomeruli so good filter?
PASSIVE and NONSELECTIVE
Powered by hydrostatic pressure (NO ENERGY), forces fljuid and solutes through filtration membrane
no large protein
no large carbs
no blood !
High pressure that forces fluid out met with forces that drive fluid back into glomerulus
Fenestration capillaries, bp higher than other capillary beds (normally 18 mmhg, in here 55 mmhg) allows
GFR is defined as?
proportional to?
Normal GFR?
Governed by three factors
Volume of filtrate per minute by all glomeruli in kindey
GFR and NFP directly proportional
120-125 ml/min
- total surface area for filtration
- Filtration membrane permeability
- NFP
what are 3 INTRINSIC controls of GFR
Renal autoregulation
myogenic mechanisms
tubuloglomerular mechanism
What is renal autoregulation
adjusting resistance of blood flow
Myogenic mechanism
stretch (when bp high) of smooth muscle (or lack of stretch) causes either vasoconstriction or vasodialation of afferent arteriole
happens with each heart beat, pump =constrction, relax = dialation
Tubuloglomerular mechanisms
macula densa cells of JGA
secrete VASOCONSTRICTOR in response to changes in osmolarity and filtrate flow in DCT
What are the 2 EXTRINSIC controls of GFR
SNS controls
RAA system
SNs controls of GFR
Extreme stress- override local renal control
Afferent arterioles constricted initally-blood goes to preferential organs
dec flow rate sensed by MACULA DENSA cells
Macula densa cells stimulage JG cells——SECRETE renin—-triggers RAA system
INCREASES BLOOD VOLUME AND BP
RAA System
Renin-angiotensin—-angiotensin I
ACE changes angio I to angio II
angio II is a VASOCONSTRICTOR - incr bp througout body, efferent arteriole constrict more than afferent
causes release of
aldosterone--increased
sodium and water
absorption causes
increased in blood volume,
systemic bp and GFR
ADH--increased water absorbtion BY OPENING WATER CHANNELS also increases BV, BP, GFR
When is renin is released by JG cells, it is caused by?
reduced stretch of JG cells
Stim of JG cells- MD, SNS, angiotensin II
Tubular reabsorption
- what is it?
- Paracellular route?
- Transcellular route?
Movement of molecules from filtrate to blood
Paracellular route- through
tight junct and into
preitubular capillaries
(h2o and ions)
Transcellular route
3 barriers
luminal membrane of
tubule celll
basolateral membrane
of tubule cell
Peritubular capillary
wall
most substances reabsorbed this way
What causes tubular reabsorption in PCT
How are sodium ions reabsorbed
How are glucose and other organics reabsorbed?
IONS, WATER, ORGANICS
sodium ion reabsorption creates gradients
drives reabsorbtion of
other substances in PCT
Luminal membrane-FACILITAED DIFFUSON COUPLED WITH COTRANSPORT
Basolateral membrane- active transport- na/k pump to release NA back into body
COTRANSPORT WITH NA ACROSS LUMINAL
FACILICATED DIFF ACROSS BASOLATERAL
PASSIVE DIFF
Tubular Reabsorption
in Loop, DCT, collecting duct
What happens in Loop?
What happens in DCT and collecting ducts?
Hormones that control DCT/Collecting ducts
25% sodium, 35%Cl, 30% K, 10% water
DCT reabsorption all is hormonally controlled
Aldosterone: works on principle cells of dct.
sodium ion reabsorption/obligatory water reabsorption, less vol of urine
ADH- target principle cells
open or synth water channels-increase water reabsorb-conc urine (change osmolarity)
ANP- decreases sodium and water reabsorption.
inhibits secretion of
aldosterone.
sodium stays in urine, takes
water with it. bv/bp down
What substances stay in urine?
urea, uric acid, creatine (excreted as creatinine
