Chem lect 20: Evaluation of Acid-Base balance

Question 1

Acids/bases

dissociation

proteins

Answer 1

• Acids: donate H+ in water
• Bases: accept H+ in water
• When an acid HA dissociates => H+ and its conjugate base (anion, A-)
• HA and/or A- can be a residue on a protein

Question 2

Normal blood pH

Answer 2

7.35-7.45

Question 3

Body Buffers

Answer 3

• HCO₃^-
• Proteins
  
  • hemoglobin
  • plasma proteins
  • primarily intracellular
• phosphates (PO₄^-3)
  *

Question 4

Buffering of Non-volatile acids

Lungs

Kidneys

Proteins and hemoglobin

Answer 4

• Lungs
  
  • don’t do much but kick in immediately
• Kidneys
  
  • do more to correct, take 2-5 days to react
  • make and conserve bicarb
• Proteins and hemoglobin
  
  • acts within minutes
  • If hemodynamics are compromised this won’t help much

Question 5

Renal Regulation of Acid/Base Balance

Answer 5

• Resorb all HCO3-
• Regenerate HC03- that titrates H+ generated from metabolism
• Regulated production of NH₃
  
  • combines with H+ to secrete NH₄+
• Normally minimal amounts of HCO3- are secreted

Question 6

Blood gas analysis

Answer 6

• Respiratory function: pCO₂
• Acid base balance (kidneys): HCO₃
• Water balance: Na⁺, K⁺
• Electroneutrality: Chloride, anion gap

Question 7

Bicarb and pCO₂

Answer 7

Always go in same direction

Crazy, retarded twins

If not a mixed ….

Question 8

If metabolic

Answer 8

• masters of science
• all the arrows go in the same direction
  
  • pH
  • HCO₃^- (bicarb)
  • pCO₂
• will have respiratory compensation
• I think this happens in kidney dz

Question 9

Respiratory origin

Answer 9

• pH goes in a different direction than bicarb and pO2
• Bicarb and pO2 will be going in the same direction

Question 10

Metabolic Acidosis

If there is an inc anion gap

causes (4)

test question

Answer 10

• 1) DKA
• 2) lactic acidosis from hypovolemia
• 3) ethylene glycol toxicity
• 4) Renal failure because of inc uremic toxins

Question 11

Anion Gap

Answer 11

• Have more unmeasured anions than unmeasured cations in body
  
  • inc in unmeasured anions bad
• Cations should always be equal to anions

Question 12

High Anion Gap Acidosis

caused by excess

Answer 12

• Ketones
• Lactic acid
• Sulfates
• Phosphates (renal dz)
• Uremic acids (renal dz)
• Ethylene glycol metabolites

Question 13

Increase in Unmeasured anions

Answer 13

Decreased HCO₃^-

Normal Cl^-

Caused by

• These are acids, will decrease bicarb from buffering
• Titrational acidosis

Question 14

Normal Anion Gap Acidosis

Caused by

Answer 14

Decreased HCO₃^-

Increased Cl^-

Caused by

• Loss of HCO₃^- rich fluids
  
  • sequestration, or secretional diarrhea
• Proximal renal tubular acidosis
  
  • dec reabsorption of HCO₃^- allows more Cl^- to be resorbed with Na⁺
• Distal renal tubular acidosis
  
  • impaired ability to secrete H⁺ and impaired secretion of Cl^- and reabsorption of HCO₃^-
• Loss of saliva in ruminants

*secretional acidosis

Question 15

Mixed Acidosis / Alkalosis

Answer 15

Dec Cl-

Inc AG

HCO3- normal to inc

Caused by

• Combined alkalosis and high AG acidosis
• Examples
  
  • High GI obstuction and lactic acidosis from shock
  • Renal failure and vomiting that increases bicarb

Question 16

Paradoxic Aciduria

Answer 16

• Sequestration of Cl- and H+ ions leaves excess bicarbonate
  
  • metabolic alkalosis
• More bicarb and less Cl are available for coupled Na absorption from proximal tubules, propagating alkalosis
• More Na than usual is presented to distal tubules, where Na reabsorption is coupled to either K+ or H+ secretion
  
  • when hypokalemia occurs, H+ ions are excreted to conserve K+
• Results in acidic urine in face of metabolic alkalosis
• Usually seen with LDAs or excessive sweating in horses