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44 Cards in this Set
- Front
- Back
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excretion= filtration + secretion - reabsorption
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formula for excretion
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25% of cardiac output
1200 ml/min |
renal blood supply
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renal artery
afferent arteriole glomerular capillary into glomerulus efferent arterioles peritubular capilaries renal vein |
flow of blood in nephron
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300 mOsm/L
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blood osmolarity in kidneys
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- reg of blood ionic composition
- reg of blood pH - reg of blood volume and BP - maintains osmolarity - hormone production - reg of blood glucose - excretion of wastes |
functions of the kidneys
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55 mmHg
BP in the glomerular capillaries |
Glomerular Blood Hydrostatic Pressure (GBHP)
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15 mmHg
opposes filtration pressure from w/in the capsule onto capillaries |
Capsular Hydrostatic Pressure
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30 mmHg
due to the presence of proteins such as albumin, globulin, fibrogen in blood plasma high ___ of plasma retains fluid in the intravascular compartment influences the magnitude of fluid movement into or out of plasma perfusing the kidney |
Blood Colloid Osmotic Pressure
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~ 10 mm Hg
the total pressure that promotes filtration |
Net Filtration Pressure (NFP)
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GBHP-CHP-BCOP
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NFP formula
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125 mL/min
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maximum filtration
GFR (Glomerular filtration Rate) # |
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720-780 mL/min
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plasma to glomerulus
aka plasma filtration |
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Ux * V / Px
Ux= urine concentration mg/mL Volume of urine flow mL/min Px= plasma concentration (mg/mL) |
Clearance measurement of "x"
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0
this substance is completely reabsorbed into plasma |
clearance of glucose
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doctors measure the clearance of __ or ___ to determine whether the kidneys of their patients are working properly
should be equal to GFR (around 120-125 mL/min) |
insulin , creatine
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a measure of the speed at which a constituent of urine passes through the kidneys
the vol of plasma from which a substance is completely removed by the kidney in a given amt of time |
clearance definition
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1. renal autoregulation
2. neural regulation 3. hormonal regulation |
factors regulating GFR
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mechanisms that maintain a constant GFR despite changes in arterial BP
1. myogenetic mechanism 2. tubuloglomerular feedback |
renal autoregulation of GFR
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increases in BP, stretch the afferent arterial
smooth muscle contracts and reduces the diameter of the arteriole; returns GFR to its previous level in seconds |
myogenic mechanism
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increases in BP raise the GFR so that fluid flows too rapidly through the renal tube (Na Cl H2O are not reabsorbed)
vasoconstrictors are released from juxtaglomerular apparatus afferent arterioles constrict and reduce GFR |
tubuloglomerular feedback
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sympathetic fibers cause vasoconstriction of afferent arterioles
w/ extreme sympathetic stimulation (exercise or hemorrhage) vasoconstriction of afferent arterioles reduces GFR (lowers urine output and permits blood flow to other tissues) |
neural regulation of GFR
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increases GFR
atria stretch and ___ is released in response relaxes glomerular cells, increasing capillary surface area |
hormonal regulation of GFR
*ANP atrial natriuretic peptide |
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reduce GFR
potent vasoconstrictor that narrows both afferent and efferent arterioles |
hormonal reg of GFR
* angiotensin II |
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proximal tubule
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99% of reabsorption here; largest amt of solute and water reabsorbed
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Na; glucose
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Most reabsorption involves ___ and ___
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H, drugs
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most secretion of __ ions and __ residues
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H+ to waste, gain HCO- in blood to act as buffer (deal w / H+ in blood)
loss of H+ coupled w/ gain of Na+ (Na+ reabsorbed, H+ secreted) |
proximal tubule acid base balance
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reabsorbs water
secretes NaCl osmolarity increases |
descending limb of Loop of Henle
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water impermeable
NaCl reabsorbed |
ascending limb of Loop of Henle
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- reabs of Nacl and Water (dependent on presence of ADH and aldosterone, inhibited by ANP)
-secretion of K and H ions |
distal tubule and collecting duct
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_____ causes reabsorption of Na and Cl and secretion of K in the collecting duct
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aldosterone (from RAAS)
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stimulates secretion of aldosterone
reduces loss of water in urine |
angiotensin II
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increases permeability to water in cells of the distal tubule and collecting duct causing higher water reabsorption
increases aquaporin, water channels, content in the apical membrane reduces loss of water in urine |
ADH antidiuretic hormone
vasopressin |
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decreases Na and water reabsorption
inhibits aldosterone and ADP release promotes natriuresis increases loss of water in urine |
ANP
atrial natriuretic peptide |
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intake>output
renal failure: excessive inc in body fluid and salt; not filtering, excreting, secreting enough |
positive balance
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output>input
endocrine defect causing excessive salt or water loss inurine or water excretion; very sensitive to ANP |
negative balance
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starts with osmolarity of 300, ends with osmolarity of 65
ANP working (blocks uptake of water into blood) |
dilute urine
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start w / osmolarity of 300, end with osmolarity of 1200
ADH and aldosterone sending water back to blood supply 1. symporters in thick ascending limb establish an osmotic gradient 2. principal cells in collecting duct reabsorb more water when ADH is present 3. urea recycling causes buildup of urea in the renal medulla |
concentrated urine
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40% solids
60%liquids |
solid to liquid amt
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2/3 intracellular fluid
1/3 extracellular fluid |
intra and extracellular fluid proportions
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80% interstitial fluid
20% blood plasma |
interstitial fluid and plasma amounts within ECF
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the most abundant buffers in body cells and blood; Hb inside RBC is a good buffer
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proteins
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important regulator of pH. the most abundant buffers in extracellular fluid
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carbonic acid---bicarbonate
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important buffers in intracellular fluid and urine
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phosphates
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