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Renal Phys 2: Renal Anatomy & Fuction Guyton ch 26
Pasley 4/20/11 lecture # 2-1 hr
44
Physiology
Undergraduate 4
04/20/2011

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Term
2 million (1 millon/kidney)
Definition
how many nephrons does the average person have?
Term
1)renal artery
2)segmental
3)interlobar
4)arcuate
*5)interlobular
*6)afferent arteriole
7)glomerular apparatus
8)efferent arteriole
9)peritubular capillaries (vasa recta on juxtamedullary neprhons)
10)veins...

* branch off the arcuate arteries
Definition
describe the arteries of the kidney starting with the renal artery and going in
Term
renal erythropoetic factor
1,25 dihydroxycholecalciferol
renin
Definition
what hormones are secreted/metabolized/excreted in the kidney?
Term
yes, they convert amino acids and non-carbs to glucose especially in prolonged fasting
Definition
the kidneys excreted metabolic waste, foreign chemicals, and regulate acid/base, arteriole pressure, and water/electrolyte excretion. Do they do gluconeogenesis?
Term
EPO is lost and so RBC's are not made (EPO is made by the liver too, but not very well, mostly made by endothelia of peritubular capillaries of kidney)
Definition
why does renal failure lead to anemia?
Term
filtration: golmerulus
secrete/reabsorb: renal tubule and peritubular capillaries
Definition
what part of the kidney does filtration? what part does secretion/reabsorbtion?
Term
filtration(Stuff passing through) - reabsorbtion + secretion

makes sense
Definition
what is the excretion equation?
Term
cortical nephrons
Definition
nephron located in the outer cortex, has short LoH, penetrate into the medulla a short distance
Term
juxtomedullary nephrons
Definition
nephrons that lie deep in the cortex adjacent to the medulla, have long LoH and extend deep into medulla
Term
juxtamedullary nephrons
Definition
what kind of nephrons have vasa recta?
Term
25% (1.1 L/min)
Definition
how much cardiac output do the kidneys get?
Term
high hydrostatic pressure -> higher GFR and decreased resorption from peritubular capillaries (stuff is flying by too fast, hard to reabsorb stuff)
Definition
what alters GFR?
Term
nothing except proteins (due to the negative charge thing + proteins are big)
Definition
what is filtration selective for?
Term
20%, the rest is re-circulated
Definition
how much of renal plasma is filtered?
Term
its important for rapidly secreting come waste products like H+ and foreign substances such as some drugs & toxins
Definition
why is secretion important?
Term
inulin & creatinine
Definition
what substances are filtered only?
Term
sodium
Definition
what substances are filtered and partially reabsorbed?
Term
glucose and amino acids?
Definition
what substances are filtered and completely reabsorbed?
Term
PAH
Definition
what is filtered and secreted only?
Term
125 mL/min or 180 L/day
Definition
what is the normal GFR?
Term
60 times
Definition
how many times a day is the entire plasma volume filtered?
Term
about the same just no large proteins
Definition
what is the difference between glomerular filtrate and plasma?
Term
GFR/Renal plasma flow ~ 0.2 (20% of plasma is filtered)
Definition
what is the filtration fraction?
Term
1) prevent passage of RBC's, WBC's, platelets
2) permits passage of water and ions
3) forms ultrafiltrate of blood
4)functions as a size & charge filter: keeps large and (-) charged particles in the plasma
Definition
what are the functions of the glomerular filtration barrier?
Term
heparin sulfate (proteoglycans in the basement membrane)
Definition
why does the glomerular filtration barrier have a strong negative charge?
Term
proteinuria
Definition
if the GFB gets damaged and loses its negative charge, what happens?
Term
small and (+) charge, cations
Definition
what kind of particals are filtered faster through the glomerular filtration barrier?
Term
NFP = glomerular filtration pressure - Bowman's capsule pressure - Golmerular oncotic pressure

in the example 10 = 60 - 32 - 18
Definition
what is the equation for net filtration pressure?
Term
Kf x NFP
Kf = filtration constant ~ 12.5 mL/min/mmHg
NFP = net filtration pressure
Definition
What does GFR = ?
Term
oncotic pressure increases (loss of fluid increases colloid osmotic pressure)

in the example, glomerular pressure stays at 60, but the oncotic pressure goes from 28 to 36
Definition
why does net filtration pressure decrease along the glomerulus?
Term
glomerular hydrostatic pressure pushing fluid out of the capillary

bowman's capsule pressure and colloid osmotic pressure of the capillary push fluid back in against the hydrostatic pressure
Definition
what are the starling forces effecting GFR?
Term
hydraulic conductivity * surface area

normally not highly variable
Definition
what determines Kf?
Term
1) chronic HTN
2) obesity/Diabetes mellitus
3) glomerularonephritis
Definition
what diseases can reduce Kf and thus GFR?
Term
normally changes as a function of GFR, doesn't regulate GFR, but
1)tubular obstruction via kidney stones and necrosis or
2) urinary tract obstructions such as prostate hypertrophy/cancer
Definition
what can change the bowman's capsule hydrostatic pressure (PB)?
Term
Glomerular Hydrostatic pressure (PG)
Definition
what GFR determinant is most subject to physiological control?
Term
1) arterial pressure (effect buffered by autoregulation)
2) afferent arteriolar resistance
3) efferent arteriolar resistance
Definition
what influences glomerular hydrostatic pressure?
Term
initially GFR increase even though the overall blood flow decreases, severe constriction decreases GFR
Definition
what happens to GFR if the efferent arteriole is constricted(resistance increases)?
Term
GFR decreases because the glomerular hydrostatic pressure decreases
Definition
what happens to GFR when the affarent arteriole is constricted(resistance increases)?
Term
afferent resistance + efferent resistance
Definition
total resistance = ?
Term
efferent arteriole: JGA (juxtaglomerular apparatus) it does contact the afferent side more though
afferent arteriole: juxtaglomerular cells
Definition
what are the components of the tubuloglomerular feedback mechanism?
Term
macula densa of the JGA
Definition
thickened region of epithelial cells lining the junction of the thick ascending limb of LoH and the DCT.

Has chemoreceptors to detect [Na] in the filtrate
Term
juxtaglomerular cells
Definition
surround wall of afferent arteriole and secrete renin, contains baroceptors that detect BP changes
Term
1)low GFR decreases distal NaCl delivery
2) this decreases NaCl reabsorbtion by the macula densa (the chemoreceptors get less NaCl)
3) this causes a decreased afferent arteriolar resistance to increase GFR back to normal

there is a negative feedback loop if the GFR gets too high
Definition
how does a low GFR initiate tubuloglomerular feedback?
Term
1)if GFR drops, less NaCl is reabsorbed by the macula densa
2) this causes afferent art. dilation & renin production from JGA -> angiotensin 2 -> increase in blood pressure & increase in efferent arteriolar resistance
Definition
how does angiotensin 2 contributes to autoregulation?
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