[21.2] buffer solutions in the body

Question 1

why does blood pH need to be controlled?

Answer 1

• enzymes have optimum pH
• different parts of body require specific pH values for effective functioning

Question 2

what pH should blood plasma and healthy blood have?

Answer 2

• blood plasma needs to be maintained at a pH between 7.35-7.45
• normal healthy blood should have a pH of 7.40

Question 3

how is pH controlled in the blood?

Answer 3

• mixture of buffers
• carbonic acid-hydrogencarbonate (H₂CO₃ / HCO₃⁻) buffer system is most important

Question 4

what happens if blood pH falls below 7.35?

Answer 4

• develop a condition called acidosis
• causes fatigue, shortness of breath, and in extreme cases, shock or death

Question 5

what happens in blood pH rises above 7.45?

Answer 5

• develop a condition called alkalosis
• causes muscle spasms, light-headedness, and nausea

Question 6

what does the carbonic acid-hydrogencarbonate buffer system do if acid, H+, is added?

Answer 6

1. [H+] increases
2. H+ ions react with conjugate base, HCO₃⁻
3. POE shifts to the left, removing most of the H+ ions

H₂CO₃ (aq) ⇌ H⁺(aq) + HCO₃⁻ (aq)

Question 7

what does the carbonic acid-hydrogencarbonate buffer system do if alkali, OH-, is added?

Answer 7

1. [OH-] increases
2. small conc of H+ ions reacts with the OH- ions to form water
3. H₂CO₃ dissociates, POE shifts to the right to restore most of the H+ ions

H₂CO₃ (aq) ⇌ H⁺(aq) + HCO₃⁻ (aq)

Question 8

how is the carbonic acid-hydrogencarbonate system maintained?

Answer 8

• body produces far more acidic material than alkaline, which the conjugate base HCO₃⁻ converts to H₂CO₃
• body prevents H₂CO₃ building up by converting it to carbon dioxide gas, which is exhaled by the lungs