final Flashcards
acid
releases hydrogen ion, can raise H conc.
base
combines w hydrogen ion, lower H conc.
strong acid
acids that more completely give up H ions = ionize
ex: sulfuric acid
strong base
bases that ionize more completely
ex: HCO3-
acidosis
hydrogen ion conc. increases, pH declines, acidity of blood increases
alkalosis
hydrogen ion conc. decreases, pH increases, solution becomes more basic
normal arterial pH
7.4
3 contributors to exercise induced muscle acidosis:
- production of CO2 and carbonic acid(HCO3-) in working skeletal muscles
- production of lactic acid in working muscles
- ATP breakdown in working muscles
volatile acid
ex: CO2
as gas that can be eliminated by lungs
- exercise adds a volatile acid load on body
what type of exercise presents a threat to acid-base disturbances?
high intensity
how does changes in muscle pH affect exercise performance?
- reduces muscle cell’s ability to produce ATP (inhibits enzymes involved in anaerobic and aerobic production of ATP)
- H ions compete w Ca ions for binding sites on troponin (hinders contractile process)
buffer
resists pH change:
removes H ions when H ion conc. increases
releases H ions when H ion conc. decreases
2 factors impacting buffer ability:
- intrinsic physiochemical ability
- conc. of buffer (the greater, the better)
4 major intracellular chemical buffer systems in cytosol of muscle fibers:
- bicarbonate
- phosphates
- cellular proteins ex: histidine
- histidine - dipeptides ex: carnosine
2 primary hydrogen transporters across sarcolemma:
- sodium-hydrogen exchangers (NHE)
- monocarboxlate transporters (MCTs)
NHE function
move sodium ions into muscle and h ions into interstitial space
(one for one)
2 types of MCTs: both do?
- MCT1
- MCT4
mediate cotransport of lactate and hydrogen out of muscle across sarcolemma
which type of muscle fiber has a higher intracellular buffering capacity?
fast/ type II
3 buffer systems of blood:
- proteins
- hemoglobin
- bicarbonate
which blood buffer is important during rest?
hemoglobin:
- high conc. = 6x buffering capacity of proteins
- deoxygenated = better bind to h formed when CO2 enters from tissues
most important buffer system in body
bicarbonate
- increased blood bicarbonate conc. = improved exercise performance
henderson - hasselbalch equation
describes ability of bicarbonate and carbonic acid to act as buffer system:
- pH of weak acid solution is determined by ratio of conc. of base in solution to conc. of acid
pH= = pKa + log10(Hco3-/h2co3)
ratio of bicarbonate to carbonic acid
20 to 1
important regulator of blood carbonic acid and pH:
lungs/ respiratory system
supplements taken to increase extracellular buffer capacity/ prevent exercise-induced acidosis:
- sodium bicarbonate
- sodium citrate
- beta-alanine
principal way kidneys regulate ion conc.
increase or decrease bicarbonate conc.
via excretion
*regulation from tubule
*reacts too slow to be important
is muscle or blood pH lower?
muscle by .4-.6 pH units - muscle H ion conc is high, and buffering capacity is lower
what does amount of h ions produced during exercise dependent on?
- exercise intensity
- amount of muscle mass involved
- duration of exercise
% contribution to cell’s buffering capactity:
- histine dipeptides = 60%
- muscle bicarbonate = 20-30%
- intracellular phosphate groups = 10-20%
respiratory compensation
respiratory assistance in buffering lactic acid during exercise - increase alveolar ventilation = reduced blood PCO2
first and second line of defence against exercise-induced acidosis
- buffers in muscle fiber
- blood buffer systems
“blowing off carbon dioxide”
increase in pulmonary during intense exercise assists in eliminating carbonic acid
atmospheric pressure
measure of weight of column of air directly over that spot
*greatest at sea level
hypoxia
lower PO2 = decreased O2 transport - altitude
normoxia
PO2 under sea-level conditions
hyperoxia
inspired PO2 is greater than at sea level
are short-term anaerobic races affected by low PO2 at altitude
no - O2 transport isn’t limiting performance
how does lower air density at altitude affect shorts movements?
less resistance to high speed movements
how does altitude impact long distance running?
VO2 max decreases in linear fashion as altitude increases
max cardiac output
max HR x max SV
what does altitude induced bradycardia suggest?
myocardial hypoxia may trigger slower HR at high altitude, decreasing work and oxygen demand of heart muscle
why does VO2 max decrease at a faster rate at higher altitudes?
- effects of desaturation of hemoglobin - moderate
- decrease in max cardiac output - high
why do submaximal performances at altitude require higher HR and ventilation responses?
- lower oxygen content of arterial blood
- reduction of # O2 molecules per L of air
