Acid-base balance

acid

any molecule that can liberate (release) H ions, therefore raising the H ion concentration above that of water

base

any molecule that is capable of combining with H ions, therefore lowering the H concentration of the solution

pH

the negative logarithm of the H ion concentration

acidosis

when a solution becomes more acidic

alkalosis

when a solution becomes more basic

major threat of acidosis or alkalosis

impact the rate-limiting enzymes and disturb the metabolic processes

an increase in intramuscular hydrogen ions can impair exercise performance in two ways (1)

reduces the muscle cell's ability to produce ATP by inhibiting rate-limiting enzymes

an increase in intramuscular hydrogen ions can impair exercise performance in two ways (2)

competes with Ca++ for binding sites on troponin, hindering contraction

a buffer attempts to maintain pH at homeostatic levels when acidosis occurs by

removing hydrogen ions when the hydrogen ion concentration gets too high

a buffer attempts to maintain pH at homeostatic levels when alkalosis occurs by

releasing hydrogen ions when the hydrogen ion concentration gets too low

intracellular buffers

proteins, phosphate groups, and bicarbonate inside the cell

extracellular buffers

proteins, hemoglobin, and bicarbonate outside the cell

the ______ system is the most important buffer system in the body

bicarbonate

the ratio of bicarbonate to carbonic acid is

20:1

the pH of the blood is

7

bicarbonate system

a weak acid (carbonic acid) that undergoes a dissociation reaction

when the amount of CO2 in the blood increases, the amount of H2CO3

increases, lowering the pH of the blood by increasing the amount of acid

when the CO2 is expired, the pH of the blood

increases by decreasing the amount of acid

when the hydrogen ion concentration increases, the kidneys

decrease the rate of bicarbonate excretion

the kidney's effect is not very important during exercise since its response to the variations in the hydrogen ion concentration is

very slow (hours)

during high-intensity exercise, the pH of the blood and intramuscular space

decreases due to the production of lactic acid

pH is lower in the muscle than blood during high-intensity exercise because of the

differences in the buffering capacities of the two spaces

muscle pH is ____ than arterial blood pH during exercise

lower; H+ is made in muscles, and during exercis,e it is pushed into the blood to maintain pH

the amount of lactic acid produced is dependent on (1)

the exercise intensity (more produced)

the amount of lactic acid produced is dependent on (2)

the amount of muscle mass involved in the activity (size principle, fast twitch = more produced)

the amount of lactic acid produced is dependent on (3)

duration of exercise bout (long = less)(short = more)

blood pH below ___ becomes life-threatening and must be corrected immediately

7

60% of the cell's buffering capacity is from the

intracellular proteins

20-30% of the cell's buffering capacity is from

intracellular bicarbonate system

10-20% of the cell's buffering capacity is from

intracellular phosphate groups

the intracellular buffering capacity is limited, so the

extracellular space must help with buffering

in the blood, the principal buffer during exercise is the

bicarbonate system; hemoglobin and proteins assist but not to the same extent

around 50-60% of VO2 max, blood pH begins to decrease due to

increase in blood lactate (LT)

an increase in hydrogen ions stimulates the

carotid bodies to increase ventilation

increase in ventilation increases the expiration of CO2 , which

lowers the acid load produced by exercise