ACID BASE BALANCE Flashcards
What is acid?
Molecule that can liberate hydrogen ions (H+).
Acids increase the H+ concentration in a solution.
Lactic acid is a strong acid.
What is a base
Molecule capable of combining with H+.
Decreases H+ concentration a solution (increases pH).
Bicarbonate (HCO3−) is a strong base.
What is the pH scale?
The concentration of H+ in a solution is expressed in pH units on a 0 to 14 scale.
pH of solutions below 7 are acidic whereas the pH of solutions >7 are basic.
pH expressed as the negative logarithm of H+ concentration.
What is the math equation?
pH = −log10[H+].
Since the pH scale is logarithmic, a change in 1 pH unit corresponds to a ten-fold change in [H+].
pH of pure water.
What is Metabolic acidosis?
Gain in the amount of acid in the body.
High intensity exercise (above lactate threshold) lasting >30 seconds.
Long-term starvation.
-Results in increased fat metabolism and elevated production of ketoacids.
Uncontrolled diabetes.
-Results in high rates of fat metabolism and diabetic ketoacidosis.
What is Metabolic alkalosis?
Loss of acids from the body.
Severe vomiting.
Kidney disease.
Sources of H+ during Exercise?
Production of carbon dioxide.
Production of lactic acid.
ATP breakdown during muscle contraction.
What does Production of carbon dioxide result in?
End product of oxidative phosphorylation.
CO2 + H2O ↔ H+ + HCO3−.
What does Production of lactic acid result in?
Glucose metabolism via glycolysis.
What dies ATP breakdown during muscle contraction result in?
Results in release of H+.
ATP + H2O ↔ ADP + HPO4− + H+.
High-intensity exercise lasting ≥45 seconds produces?
large amounts of H+.
In some sports, risk of acid-base disturbance is directly linked to effort of the competitor. What are the risks?
Playing at 100% effort increases risk of acidosis.
Sprint to finish in distance event increases risk of acidosis.
Why can acidosis impair exercise performance?
Contributes to muscle fatigue.
Increasing blood buffering capacity may improve performance in some events.
High intensity exercise results in production of?
lactic acid and increased [H+] in muscle fibers and blood.
How can Increased [H+] can impair performance?
Inhibits glycolytic and TCA enzyme activity (that is, ATP production).
[H+] can impairs muscle contraction by competing with Ca+2 for binding sites on troponin.
What are the Acid-Base Buffer Systems?
Intracellular buffers.
Extracellular buffers.
How is Acid-base balance maintained by buffers?
Release H+ ions when pH is high.
Accept H+ ions when pH is low.
What are Intracellular buffers?
Proteins.
Phosphate groups.
Bicarbonate.
What are Extracellular buffers?
Bicarbonate.
Hemoglobin.
Blood proteins.
Bicarbonate buffering system equation (Henderson-Hasselbalch equation)?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−
Why use the Henderson-Hasselbalch equation?
Used to calculate the pH of a solution when known amounts of acids and conjugate bases are present.
pH = pKa + log10(HCO3−/H2CO3).
Compared to slow type 1 muscle fibers, fast (type 2) muscle fibers have a?
higher buffering capacity
Compared to slow type 1 muscle fibers, fast (type 2) muscle fibers have a?
higher buffering capacity
High intensity exercise training improves muscle buffering capacity due to?
increases in carnosine and hydrogen ion transporters in the trained muscle fibers.
T or F: Diets low in acids can increase plasma pH but do not improve performance during very heavy or severe exercise.
True
Some sports regulatory agencies have banned the use of?
sodium buffers during competition.
What is the importance of Supplementation with sodium bicarbonate?
Important extracellular buffer.
Can increase time to exhaustion during high-intensity exercise (80 to 120% VO2 max).
Associated with nausea and vomiting.
Large doses can promote alkalosis.
What is the importance of sodium citrate?
Improves extracellular buffering capacity and can improve performance during high-intensity exercise (events lasting 120 to 240 seconds).
Large doses can cause alkalosis and promote nausea/vomiting.
What is the importance of beta-alanine?
Precursor to carnosine synthesis.
Carnosine serves as an intracellular buffer and can increase time to exhaustion during high-intensity exercise (events lasting 1 to 4 minutes).
Only known side effect is paraesthesia (tingling of skin).
What is the Carbonic acid dissociation equation?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−.
What is the Carbonic acid dissociation equation?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−.
When pH decreases. what increases?
[H+] increases.
Reaction moves to the left.
CO2 is “removed” by the lungs, eliminating H+ and increasing pH.
Kidneys are important in?
long-term acid-base balance.
Kidneys do not play a key role in acid-base balance during exercise.
Kidneys contribute to acid-base balance (at rest) by?
regulating bicarbonate concentration in blood.
When blood pH decreases, bicarbonate excretion is reduced.
When blood pH increases, bicarbonate excretion is increased.
H+ production depends on?
Exercise intensity.
Amount of muscle mass involved.
Duration of exercise.
What is blood pH?
Declines with increasing intensity of exercise.
What is blood pH?
Declines with increasing intensity of exercise.
What is Muscle pH?
Declines with increasing intensity of exercise: muscle pH is lower than blood pH.
Muscle is site of H+ production and has lower buffering capacity.
Buffering of H+ in the muscle is caused by (%)?
60% by intracellular proteins.
20 to 30% by muscle bicarbonate.
10 to 20% by intracellular phosphate groups.
What does Buffering of lactic acid in the blood do?
Bicarbonate is major buffer.
Increases in lactic acid accompanied by decreases in bicarbonate and blood pH.
Hemoglobin and blood proteins play minor role.
What is the First line of defense
Intracellular buffers.
What does Buffering of lactic acid in the blood do? (In terms of defense)
Blood buffers.
Respiratory compensation for exercise-induced metabolic acidosis.
