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Physiology - Block 3 - Part 2

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davidwurbel7's version from 2015-11-19 22:04

Renal Regional Transport

Question Answer
Maximum rate at which glucose can be reabsorbed in the ideal nephron375 mg/min
[Glucose(plasma] x GFRFiltered Load (mg/mL)
Plasma glucose concentration at which glucose first appears in the urineRenal Threshold
Renal threshold200 mg/dL
200 mg/dL is equal to this in mg/mL2 mg/mL
Drug that competitively inhibits glucose binding with SGLTPhlorhizin
Sodium balance is the function of this organKidneys
Maximum percentage(67%) of filtered sodium is reabsorbed herePCT
Moderate percentage(25%) of filtered sodium is reabsorbed hereLoop of Henle
5% of filtered sodium is reabsorbed hereEarly DT
3% of filtered sodium is reabsorbed hereLate DT and CD
Aldosterone's action acts hereLate DT and CD
80-90% of filtered this is reabsorbed indirectlyHCO3-
Inhibts carbonic anhydrase enzyme on both Luminal membrane and in the PCT cellAcetazolamide and Dorzolamide
Enzyme that converts carbonic acid into CO2 and H2OCarbonic Anhydrase
Carbonic anhydrase inhibitors act at this part of the nephronProximal Convoluted Tubule
Carbonic anhydrase is used for patients that develop this as a result of hyperventilation to induce metabolic acidosisRespiratory Alkalosis
Carbonic anhydrase is used for patients that develop this due increase intraocular pressureGlaucoma
Hypovolumemia can lead to this as more HCO3- is reabsorbed back into the bloodMetabolic Alkalosis
The osmolarity of the fluid entering the proximal convoluted tubule is300 mOsm
The osmolarity of the fluid in the Bowman's space is300 mOsm
Blood flow x the difference of oxygen concentration between the artery and veinOxygen Consumption
Permeable to water and small solutes such as NaCl and ureaThin Descending Limb of LOH
Permeable to NaCl and urea, but it is impermeable to waterThin Ascending Limb of LOH
The permeability of the late DCT and CD is dependent upon the presence or absence ofADH
Some K+ that is reabsorbed into the cell leak back out into this causing the it to become positive potentialTubular Fluid
The positive potential of the tubular fluid causes the reabsorption of these positive ionsCa+2 and Mg+2
Na+-K+-2Cl- Cotransporter is inhibited by the use of this drugLoop Diuretics
The most common loop diureticFurosemide
DOC of the treatment of hypercalcemiaFurosemide
Normally reabsorbs about 25% of the filtered Na+Thick Ascending Limb of LOH
Ca+2 and Mg+2 is reabsorbed by this routeParacellular Route
Normally reabsorbs about 25% of the filtered Ca+2 and Mg+2Thick Ascending Limb of LOH
Reabsorption of NaCl (5%) without water. Impermeable to water. Dilution of tubular fluid (cortical diluting segment). Site of action PTH which stimulates reabsorption of calciumEarly DT
Site of action of thiazide diuretics (Eg: HydrochlorothiazideEarly DT
Used for treatment in hypertensionThiazide Diuretics
Side effect of loop and thiazide diureticsHypokalemia
Cells involved in Na+ reabsorption, K+ secretion, and water reabsorptionPrincipal Cells
Cells involved in K+ reabsorption and H+ secretion (bicarbonate reabsorption)α-Intercalated Cells
Increases number of epithelial sodium channels (ENaC) & increases Na+ reabsorptionAldosterone
Inhibits sodium reabsorption in the Late DT and Collecting duct (CD)Atrial Natriuretic Peptide (ANP)
An aldosterone antagonist which blocks Aldosterone induced synthesis of Epithelial Na+ channels on P cells thereby preventing Sodium reabsorptionSpironolactone
Side effect of spironolactoneHyperkalemia
Long term treatment diuretic in CHFSpironolactone
Portion of the nephron responsible for K+ balanceDCT and Collecting Duct
Aldosterone increases secretion of H+ by increasing the activity ofH+-K+ ATPase
In acidosis, potassium moves out of the cell resulting inHyperkalemia
In alkalosis, potassium moves in to the cell resulting inHypokalemia
Hypocalcemia and hypokalemia is seen inMetabolic Alkalosis
Hypercalcemia and hyperkalemia is seen inMetabolic Acidosis
Balance of this is done by combination of filtration, reabsorption and secretion by the kidneysPotassium
The site of K+ balance within the nephronDCT and Collecting Duct
Electrochemical gradient for K+ makes its movement into lumen. The magnitude of K+ secretion depends on size ofElectrochemical Gradient
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Renal Clearance

 

Question Answer
The theoretical volume of plasma from which a substance is removed over unit timeClearance
Usub (Concentration of substance in urine (mg/mL)) x V (Volume of urine per minute (mL/min)) / Psub (Concentration of substance in plasma (mg/mL))Clearance Formula
Clearance value indicates that either the substance is reabsorbed highly or not at all handled by kidneysLow Clearance Value
Clearance value indicates that the substance is secreted highly & not reabsorbed in the kidneysHigh Clearance Value
Freely filters, but does not secrete or reabsorbInulin
The clearance of Inulin is equal to thisGFR
If clearance of a substance is less than inulin clearance. This means that less volume of plasma is cleared of the substance, hence there isNet Reabsorption
If clearance of a substance is greater than inulin clearance. This means that more volume of plasma is cleared of the substance, hence there isNet Secretion
Index of renal functionGFR
Since no other organ than the kidney extracts PAH, PAH concentration in renal artery is equal to PAH concentration in anyPeripheral Vein
PAH is secreted from the nephron byCo-Transport Mechanism
Renal Plasma Flow / 1- HematocritRenal Blood Flow Formula
Plasma flowing to the nephrons, excluding plasma flowing to renal capsule, fat around the kidneysEffective Renal Plasma Flow
This is only 90% of actual renal plasma flowEffective Renal Plasma Flow
Effective Renal Plasma Flow is equal toPAH Clearance
U (PAH) x V / P (PAH)PAH Clearance Formula
U (Osm) x V / P (Osm)Clearance of Water Formula
Kidney is conserving water resulting in excretion of a concentrated urineNegative Free Water Clearance
Kidney is producing dilute urine by excreting an additional volume of solute-free waterPositive Free Water Clearance
Kidney is producing a urine that is isosmotic with plasmaNo Free Water Clearance
Lowest urine osomolarity the kidneys can produce50 Osm
Highest urine osomolarity the kidneys can produce1200 Osm
Drug that blocks reabsorption for glucosePhlorizine
Sodium always appears in the urinePositive Clearance
Aldosterone by increasing the reabsorption of sodiumDecrease Clearance
ANP by inhibiting reabsorption of sodiumIncrease Clearance
Bicarbonate. Glucose TF/P ratioSubstances TF/P less than 1
Inulin, Urea, PAH TF/P ratioSunstances TF/P greater than 1
Amount of water reabsorbed in the proximal convoluted tubule2/3rds
If the TF/Pinulin= 2.0, this amount of water is reabsorbed50%
If the TF/Pinulin= 3.0, this amount of water is reabsorbed67%
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Concentration Dilution of Urine

Question Answer
Water reabsorption in PCT67%
Water reabsorption in LOH20%
Water reabsorption in In DT and CD13%
Water reabsorption in DT and CD is under the influence of this hormoneADH
ADH binds to this receptor in the DT and CDV2
This solute in addition to Na+ in the interstitium is responsible for maximal reabsorption of waterUrea
The increasing osmolarity of the medullary to due to increase this in the cortex and a reduced this in the medullaBlood Flow
This increases the water permeability of DT and CDADH
This increases the activity of Na+-K+-2Cl- cotransporterADH
This increases urea permeabilityADH
The increase the activity of Na+-K+-2Cl- cotransporter in the thick ascending limb enhancesCountercurrent Multiplication
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Acid-Base

Question Answer
Normal arterial plasma concentration of bicarbonate24 mmol/L
Normal arterial plasma concentration of bicarbonate range22 - 28 mmol/L
Normal arterial plasma concentration of P(a) CO240 mmHg
pH = pK + log [A-] / [HA]Henderson-Hasselbalch Equation
pH = 6.1+ log [HCO3− ] / [PCO2 ]Henderson-Hasselbalch Equation for Bicarbonate
The most important ECF/plasma buffer because concentration is high in ECF. Acid form can easily be altered by the respiratory system. Base form can easily be altered by the kidneysBicarbonate/Carbonic Acid (CO2) Buffer
Less important buffer because of its low concentration in the ECFInorganic Phosphate Buffer
Condition in which there is an increase in [H+] or decrease in pH of arterial bloodAcidosis
Condition in which there is a decrease in [H+] or an increase in pH of arterial bloodAlkalosis
Occurs in all conditions that cause difficulty in elimination of CO2 from the body. There is accumulation of volatile acid (CO2 retention)Respiratory Acidosis
A decrease in pH as a result of increase in CO2 with HCO3- remaining within normal limitAcute Respiratory Acidosis (Uncompensated Respiratory Acidosis)
A decrease in pH as a result of increase in CO2 with elevated HCO3-Partially Compensated Respiratory Acidosis
Normal pH with increase in CO2 and elevated HCO3-Compensated Respiratory Acidosis
Inhibition of respiratory medullary center, Disorders of the respiratory muscles (weakness or paralysis), Disorders of Gas exchange, Airway obstruction are causes ofRespiratory Acidosis
Stimulation of medullary respiratory center, Hypoxemia, pulmonary embolism and Mechanical ventilation are causes ofRespiratory Alkalosis
An increase in pH as a result of decrease in CO2 with HCO3- remaining within normal limitAcute Respiratory Alkalosis (Uncompensated Respiratory Alkalosis)
An increase in pH as a result of decrease in CO2 with decrease HCO3-Partially Compensated Respiratory Alkalosis
Normal pH with decrease in CO2 and decrease HCO3-Compensated Respiratory Alkalosis
Occurs in all conditions that cause a decrease in bicarbonate in ECF due to addition of non-volatile acids. Addition of non-volatile acids consume bicarbonateMetabolic Acidosis
Most common cause of metabolic acidosisDiarrhea
Renal loss of HCO3- (failure to reabsorb HCO3- ) due to lowered threshold for HCO3- reclaimation leading to metabolic acidosisType 2 Renal Tubular Acidosis (type 2 RTA)(Proximal)
Decreased excretion of H+ (retension of organic acids like phosphoric acid and sulfuric acid) leading to metabolic acidosisChronic renal failure
Dysfunctional aldosterone mediated H+ ATPase pump in CD. Decreased excretion of H+. Decreased ability to acidify urine leading to metabolic acidosisType 1 RTA (Distal)
Due to destruction of the Juxtaglomerular apparatus -> low renin and low aldosterone - Hyporenemic Hypoaldosteronism leading to metabolic acidosisType 4 RTA
Occurs in conditions in which there is loss of non- volatile acid from the body. There is an increase in bicarbonate concentration in ECF/plasma. Can occur in cases of severe vomiting.Metabolic Alkalosis
Can result in this because of this loss of H+, gain of HCO3- or volume contractionMetabolic Alkalosis
Most common cause of metabolic alkalosisLoop or Thiazide Diuretics
Increase in urinary acidity (decrease in urine pH), Increased NH4 formation from ammonia. Increased H2PO4 - / HPO4 -2 ratio in urine (Titratable acidity). Decreased bicarbonate excretion in urineConsequences of Renal Compensation in Acidosis
Decrease in urinary acidity (increase in urine pH). Decreased NH4 formation from ammonia. Decreased H2PO4 - / HPO4 -2 ratio in urine. Increased bicarbonate excretion in urineConsequences of Renal Compensation in Alkalosis
The difference between number of sodium ions and the sum of chloride and bicarbonate ion in plasmaPlasma Anion Gap (PAG)
Normal range is 10 ± 2 mEq/LNormal Ion Gap Range
Due to decreased blood flow to kidneys as seen in low blood volumePre-Renal Renal Failure
Damage to glomeruli, renal tubules, interstitium Intrinsic Renal Failure
As a result of urinary tract obstruction as seen in Benign prostatic hyperplasia (BPH), Nephrocalcinosis (kidney stones) in the bladder, renal malignancyPost-Renal Renal Failure
Decreased urine output (oliguria) - less than 0.5ml/kg/hr for more than 6 hours. Rapid rise in BUN & Serum creatinine over a period of several hours to daysAcute Renal Failure Diagnosis
Progressive loss of renal functions over a period of months or yearsChronic Renal Failure
Diabetes Mellitus, hypertension, glomerulonephritis are common causes ofChronic Renal Failure
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