Nephro Exam 3: OSTROM Acid-Base

Henderson-Hasselbalch Equation

• pH = pK + log ([_____] / [_____])

• Dissociation constant (pK) → 6.1

• pH = 6.1 + log ([_____] / [_____])

• Blood-Gas measures blood _____ and _____

• CO2 Solubility Coefficient → 0.03

• pH = 6.1 + log ([HCO3] / (PCO2 x 0.03)) for PCO2 in mmHg

base, acid, HCO3, H2CO3, pH, PCO2

Henderson-Hasselbalch Equation

• Kidneys maintain Serum _____ around _____ mEq/L

• Liver maintains _____ around _____ mmHg

• pH = 6.1 + log (24 / (40 x 0.03)) = 6.1 + 1.3 = 7.4

  • If acid load = HCO3 concentration _____ → pH _____

HCO3, 24, PCO2, 40, decreases, decreases

Compensatory Mechanisms of Acid-Base Homeostasis

• Extracellular buffering → _____ (Primary Buffer)

  • Others: plasma proteins, Hgb, phosphates

  • Primary Urinary Buffer → _____

• Ventilatory regulation of CO2 elimination → _____ = decrease in _____

• Renal regulation of H+ and HCO3 excretion → _____

Bicarbonate-Carbonic Acid, Ammonia, hyperventilation, PCO2, day(s)

Renal Regulation of Acid-Base Homeostasis

• PROXIMAL tubule: _____ reabsorption

  • Forms _____ → Broken down to _____ and _____ by CA

  • Diffuses into _____ → reforms _____

  • It dissociates the former _____ → secreted into the _____ lumen → _____ that exits the cell and enters the peritubular capillary

HCO3, carbonic acid, CO2, H2O, proximal, carbonic acid, H+, tubular, HCO3

Renal Regulation of Acid-Base Homeostasis

• Distal tubule and Collecting duct: _____ excretion

  • _____ and _____ are generated intracellularly from CO2 and H2O

  • _____ is actively secreted into tubular lumen by _____-ATPase

  • _____ exits and enters the peritubular capillary in exchange for _____

acid, H+, HCO3, H+, H+, HCO3, Cl

Acid-Base Disturbances

• Metabolic → _____ and Respiratory → _____

• Metabolic Acidosis → _____ pH and HCO3

• Metabolic Alkalosis → _____ pH and HCO3

• Respiratory Acidosis → _____ pH and _____ PCO2

• Respiratory Alkalosis → _____ pH and _____ PCO2

HCO3, PCO2, decreased, increased, decreased, increased, increased, decreased

S/Sxs of Acid-Base Disturbances

• Sxs of Acidosis: CNS + _____ + Muscular System (_____, _____)

• Sxs of Alkalosis: CNS + Muscular System (_____, _____) + _____ (_____)

pH disturbances shift this delicate balance and disrupt _____ transport of _____ and _____

Heart, seizures, weakness, twitching, spasms, Digestive System, N/V, Hgb, O2, CO2

Metabolic Acidosis Pathophysiology

• pH _____

• Serum Anion Gap (SAG): Gap → _____

• SAG = [_____] – [_____] – [_____] = [_____] – [_____]

  • UAs: Unmeasured Anions and UCs: Unmeasured Cations

• SAG can be used to infer whether _____ or _____ acidosis is present

• High Anion Gap: _____

  • Accumulation of UAs → _____, _____, and _____

• Normal Anion Gap: _____

  • SAG is normal, but _____ replaced by _____

<7.35, unmeasured anions, Na, Cl, HCO3, UAs, UCs, organic, mineral, Metabolic Acidosis, ketoacidosis, lactic acidosis, toxins, Hyper-Cl Metabolic Acidosis, HCO3, Cl

Metabolic Acidosis Pathophysiology

• Metabolic Acidosis + _____ (intro to _____) + _____ (no intro to _____)

  • GI → Toxins (_____) → _____

    • Toxicity: MethaNOL → MethaNAL(formaldehyde) → MethaNOIC ACID (formic acid)

  • ECF → _____ → _____

  • Renal → _____, _____ → _____ wasting and _____ Acidosis (RTA)

• Tx → _____ or _____

Elevated AG, UAs, Hyper-Cl, UAs, methanol, diarrhea, Organic Acids, Cl, Organic Anions, Phosphates, HCO3, Renal Tubular, Na Bicarb, Tromethamine (THAM)

Metabolic Alkalosis Pathophysiology

• pH _____

• Increases in serum _____

• Metabolic Alkalosis + Causes

  • Volume-MEDIATED processes + urinary _____ mEq/L caused by GI d/o, _____ therapy, excessive _____ therapy, Mild/Moderate _____ deficiency, Cystic fibrosis, correction of chronic hypercapnia

  • Volume-INDEPENDENT processes + urinary _____ mEq/L causes Excessive MRA activity, black licorice, _____ depletion, _____ deficiency

  • Unclassified causes: massive blood or plasma fraction transfusion and carb refeeding after starvation

>7.45, HCO3, Cl <10, diuretic, HCO3, K, Cl >20, K, Mg

Metabolic Alkalosis Pathophysiology

• Tx → Volume-MEDIATED/Na-Cl-_____ D/o (_____, _____, _____ Monohydrochloride) + Volume-INDEPENDENT/Na-Cl-_____ D/o (underlying cause of _____, _____)

Responsive, HCl, Ammonium Chloride, Arginine, Resistant, MRA excess, Methylprednisone

Respiratory Acidosis Pathophysiology

• Results from 

  • _____ of central _____ (_____)

  • Airway conductance

  • Impair pulmonary gas diffusion

  • Interfere w/NM function

  • _____

• Tx → Improving _____

• Causes: drugs, _____, _____ injury, infarction, status epilepticus, _____ obstruction, _____, _____, ARDs, Increased _____ production

inhibition, respiratory center, opioid overdose, life-threatening, ventilation, stroke, head, airway, asthma, COPD, CO2

Respiratory Alkalosis Pathophysiology

• Characterized by a primary decrease in _____ → _____ pH

• Increase in ventilatory excretion of _____ (_____)

• Hyperventilation

  • Increase in neurochemical _____ via either central or peripheral mechanisms

  • _____ or _____ (iatrogenic) hyperventilation

• Tx → _____

• Causes

  • Central stimulation → _____

  • Hypoxemia or tissue hypoxemia → _____

PCO2, increased, CO2, hyperventilation, stimulation, Voluntary, Mechanical, slowing breathing, anxiety and pain, severe anemia

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