lecture 14 Flashcards
(12 cards)
review of important concepts
- lactate concentration
- increase in blood lactate has an acidifying effect (i.e. increase protns [H+] —> decrease pH) - buffering protons
- bicarbonate (HCO3) combines with H+ to form water and carbon dioxide, thereby preventing the increase in [H+];
H+ + HCO3 <—> H2O + CO2
caronic anhydrase (catalyzed) - CO2 production and breathing
- ventilation keeps CO2 from accumulating and drives the carbonic anhydrase rxn towards production of CO2 and “consumption” of H+
- body increasing CO2
- respiratory acidosis (holding breath)
two metabolic boundaries
lactate threshold (LT)
- the metabolic rate (or VO2) at which blood lactate can be maintainedat resting levels
- separates moderate from heavy intensity exercise domains
critical intensity (CI) or critical threshold or maximal metabolic steady-state
- the highest VO2 at which a heightened lactate production in muscle may be stabilized in blood
- separates heavy from severe intensity exercise domains
incremental exercise
we can detect these “boundary crossings” by measuring gas exchange and ventilation at the mouth
moderate —> LT —> heavy —> CT —> severe
below the lactate threshold moderate-intensity exercise
just carbohydrates
blood lactate 1 to 2 mL per 1L blood
- never zero
below LT
La - no change
HCO3 - no change
pH - get rid of CO2 to maintain pH
increase Ve, increase VCO2, increase VCO2 —> slopes are the same
PETCO2 - 38-42 (40mmHg)
Lactate at resting concentrations
-low production, rate of lactate appearance equals disappearance
some muscle fibres might produce La —> type 2, weak fibers
La leaves capillary, converts to pyruvate in the muscle cell then pyruvate —> La (using LDH enzyme) then into the capillary as La
blood [La] < 2 mmol/L
ventilation is hyperpnea
- PaCO2 = 40mmHg
- pH = 7.4
above the lactate threshold (heavy-intensity exercise)
oxidative phospholyation - bigger, higher rate of O2, which then creates more CO2
G-6-P —> arrows thicker ATP sythesis has increased (happens faster)
La —> transported into blood constantly
extra source of CO2, due to buffering
La —> starts to increase, (protons and HCO3), both together create CO2 and H2O
HCO3 —> slight decrease in HCO3 as creating more CO2
pH —> no change because HCO3 still there
Vt = first ventilatory breakpoint
GET = gas exchange threshold (breakpoint in VCO2)
lactate elevated — but stable
- elevated lactate production, rate of lactate appearance equals disappearance
La leaves capillary, converts to pyruvate in the muscle cell then pyruvate —> La (using LDH enzyme) then into the capillary as La
blood [La] > 2 mmol/L
(~ 3-7mmol/L @steady state)
- more muscle fibers are engaged
- more la being put into capillarys, as well as more La being removed from blood (pretty even)
ventilation —> hyperpnea
- functioning properly to reduce acidosis
- PaCO2 = 40mmHg
- pH = 7.4
above the critical intensity (severe-intensity exercise)
hyperventilation occurs
Ve —> breathing in a lot more
La —> rises
HCO3 —> falls
pH —> not maintained
RCP = respiratory compensation point
Vt2 = second ventilatory breakpoint
lactate elevated and unstable
- high production, rate of lactate appearance exceeds clearance
La leaves capillary, converts to pyruvate in the muscle cell then pyruvate —> La (using LDH enzyme) then into the capillary as La, with reversible enzyme LDH from La to pyrvuate
blood [La]»_space; 2 mmol/L (~8-15 mmol/L @ end)
- La blood concentration rises
- more muscle fibers producing La, not enough taking them out
hyperventilation occurs
- PaCO2 = 30mmHg
- pH = 7.2
two metabolic thresholds
- unique to incremental exercise
GET/Vt1
- the VO2 at the onset of bicarbonate buffering where VCO2 and Ve begin to increase at a greater rate than VO2
- ~ LT
- separates moderate from heavy intensity exercise domains
RCP/Vt2
- the VO2 at which bicarbonate buffering cannot prevent aciosis nd hyperventilation ensures to compensate for —> cannot compensate on it’s own
- ~CI
- separates heavy from severe intensity exercise domains
variability
females
untrained: moderate to heavy … GET —> at teir like highest level won’t last 5 mins
trained: heavy to severe … RCP —> barely getting trained, can do it for hours
from 70-75, the same physiological effects for a high untrained and a low trained athletes
RCP and performance
higher RCP the faster you can complete 2 miles
- positive linear graph
