Chapter 11 - exam 2 Flashcards
H+ production depends on what three things
- exercise intensity
- amount of muscle mass involved (need more E and higher H+)
- duration of exercise
what pH declines more dramaticlaly than blood pH
muscle pH – b/c source of H+ production
What are the sources of hydrogen ions in skeletal muscle
- aerobic metabolism of glucose –> carbonic acid –>
- anaerobic metabolism (glycolysis) of glucose –> lactate
- ATP breakdown and release of H+ ions
hydrogen ions (H+) increase
What are the three sources of H+ ions during exercise
- production of carbon dioxide
- production of lactic acid
- ATP breakdown
Explain how CO2 adds to H+ ion production during exercise
Because it is the end product of oxidative phosphorylation
CO2 + H2O <-> H2CO3 <-> H+ + CO3-
How does the production of lactic acid add to the amount of H+
due to glucose metaoblism via glycolysis
lactic acid <-> lactate + H+
* dissociate = extra H+ ions = number of H+ ions is relatively low
How does ATP breakdown result in more H+ during exercise
release of H+
- ATP + H2O <-> ADP + HPO4- + H+
How does high [H+] impair performance (2 ways)
- inhibits enzymes in aerobic and anaerobic ATP production
- [H+] impair muscle contraction by competing w/ Ca2+ for binding sites on troponin
- w/o Ca2+ binding no contraction/force production
- H+ can also bind to hemoglobin – effect distribution/availability of O2
the binding of H+ to hemoglobin causes what
confirmation change of hemoglobin when bind to H+ that causes offloading of O2
What are the effects of graded exercise on arterial concentrations of bicarb, lactate, and pH
bicarb: decreases w/ graded exercise
lactate: increases w/ graded exercise (more conversion from lactic acid –> lactate + H+
pH: decreases w/ graded exercise (H+ is increasing = more acidic)
what is the acid-base balance maintained by
maintained by buffers
* release H+ ions when pH is high
* accept H+ ions when pH is low
What are the lines of defense against pH change during intense exercise
- cellular buffer systems: primary b/c its the source of H+ formation
- blood buffer systems
What are the four types of defense from cellular buffering systems
- bicarbonate (convert strong acid to weak acid)
- phosphates
- proteins
- carnosine
3 + 4 = accept H+ and able to get rid of H+ in blood
How do hydrogen ions transport in skeletal muscle
use the
- NHE (Na+ in and H+ out)
- MCT (Lactate out and H+ out)
What type of muscle have a higher buffering capacity
type 2 muscle fibers have a higher buffering capacity than slow type 1 muscle fibers
- b/c high intensity = improve muscle buffering due to higher carnosine and H+ ion transporters in trained muscle fibers
What type of training improves muscle buffering capacity…why?
high intensity exercise training improves muscle buffering capacity due to increase in carnosine and H+ ion transporters in trained muscle fibers
- upregulate transporters that move H+ out of muscle = trained better than untrained
What is the second line of defense to change in pH and what are the factors that effect it
blood buffering system (get H+ from inside muscle) –>
respiratory compensation for metabolic acidosis (as produce high CO2 use bicarb to help buffer) –>
- bicarbonate = major % of buffering blood
- phosphates – accept H+
- proteins – accept H+
What are the two factors of regulation of acid-base balance during exercise
- bicarb buffering system
- when pH decreases –> [H+] increases
- reaction moves to the left
- CO2 is “removed” by the lungs, eliminating H+ and increasing pH –> push rxn other way
Elevated CO2 levels push the equilibrium equation to the ________ creating more ________ and a ________ blood pH
right, H+, lower
as the blood pH decreases what happens to the respiratory system
low pH –> more acidic –> respiratory system activated –> ventilation increases
What is the ventilatory threshold caused by (2 things)
- increaseing blood PCO2 and H+
- increases in blood K+, rising body temp, elevated blood catecholamines, and neural influences
Patients with McArdle’s disease indicates what w/ LT vs VT
they dont have LT b/c they cannot produce lactate but still have a VT becuase H+ comes from CO2 production during graded exercise
Explain how arterial PO2, PCO2, and pH and ventilation is effected with grade exercise in untrained subjects
arterial PO2= remains unchanged
arterial PCO2 = unchanged until almost VO2max when ventilation increases rapidly (b/c exhaling more CO2)
arterial pH = unchanged until almost VO2 max when ventilation increases rapidly = more H+
Ventilation = linear increase up to 50-75% VO2max –> exponential rise
how does venous PO2 decrease during graded exercise
- deliver more O2 to tissue b/c gradient is larger at higher intensity
- decrease in muscle pH = allow more O2 to be deliered
why does arterial PCO2 decrease at max ventilation during graded exercise
hit respiratory limit = hyperventilate == and increase CO2 output
what is the precursor for carnacine
beta alanine
What are th two ways there is regulation of acid-base via the kidneys
- kidneys are important in long-term acid base balance – regulate pH but very slow in buffering (best at rest) –bloodflow cut off b/c not essential
- kidneys contribute to acid-base balance (at rest) by regulating blood bicarb concentration
hwo do the kidneys balance acid-base by regulating the blood bicarb concentration
- when blood pH decreases (high H+) bicarb excretion is reduced
- When blood pH increases (low H+) bicarb excretion is increased
what are the 3 ways that lactate is removed following exercise
- 70% of lactic acid is oxidized - used as substrate by heart and skeletal muscle
- 20% converted to glucose (via Cori cycle)
- 10% converted to Amino acids
Lactic acid is removed more rapidly with what and why
light exercise in recovery
- optimal intensity of recovery exercise = 30-40% Vo2 max
- bloodflow increases to the area of need = liver –> clearing lactate
