ventilatory response to exercise Flashcards
what is the O2 dissociation curve
hemoglobin not always 100% saturated with O2 (% of Hb bound to O2)
what is the relationship between SaO2 and PaO2
s-shaped
arterial PO2 (PaO2) determines arterial saturation (SaO2)
- increased O2 availability increases the affinity of hemoglobin for O2
what is the relationship between partial pressure and O2 affinity to hemoglobin
as partial pressure goes down, affinity to Hb goes down and saturation goes down
- high partial pressure (arteries) = little O2 released = high saturation
- low partial pressure (muscles) = Hb releases some O2 = lower saturation
- extremely low partial pressure (mito) = almost all O2 released
what is left shift of the O2 dissociation curve (haldane effect)
left shift = increased affinity
- higher affinity between O2 and hemoglobin (more O2 held onto)
- occurs mainly at rest
what is right shift of the O2 dissociation curve (bohr effect)
right shift = decreased affinity (bind O2 looser)
- affinity between hemoglobin and oxygen decreases
- more O2 released
- occurs during exercise
when does the haldane effect (left shift) occur
REST
- increased pH (more basic)
- decreased temp
- decreased CO2
when does the bohr effect (right shift) occur
EXERCISE
- decreased pH (more acidic)
- increased temp
- increased CO2
what are the primary and secondary factors controlling ventilation at rest
primary = humoral factors
secondary = neural factors
what are the primary and secondary factors controlling ventilation during exercise
primary = neural factors
secondary = humoral factors
what are neural factors
related to movement
- motor cortex (voluntary mvmt)
- stretch receptors in lungs and airway (mechanoreceptors)
- proprioceptors in muscles, joints, and tendons
- vagal tone
what are examples of the intrinsic firing of the respiratory centre in neural factors
fight or flight (start of exercise)
- no signal from anywhere but activates respiratory area - withdrawal of vagal tone and activation of sympathetic response
emotional status
what are humoral factors
central and peripheral chemoreceptors
how do central chemoreceptors work as humoral factors
in the medulla
- responds to decreased pH and increased CO2
- activates brainstem and increases ventilation
how do peripheral chemoreceptors work as humoral factors
in aortic/carotid bodies
- responds to decreased PO2, increased CO2 and decreased pH
- monitors arterial blood
how is respiration controlled at rest
partial pressure of CO2 and H+ play the main role (1. humoral)
emotional factors, psych factors, vagal tone (2. neural)
how is respiration controlled during exercise
primarily neural factors
- increase in PaCO2 and H+ can contribute as well (humoral)
what are the phases of ventilation in response to constant load exercise (and their factors)
rest = humoral
I anticipation = neural
II exponential = neural and humoral
III steady state = neural and humoral
recovery = neural first, humoral second
what is involved in the anticipation phase
very beginning of exercise (ex. starting line)
- neural factor - fight or flight situation
what is involved in the exponential phase
speeding up rate of exercise
exponential increase in ventilation
what is involved in the recovery phase
fast decline in ventilation
1. first mechanism = neural (exercise to rest - no movement activation)
2. second mechanism = humoral (chemical response takes longer to activate humoral factors)
does ventilation limit performance in untrained individuals
NO
- resp system is over built for exercise
- exceeds the capacity of the CV and skeletal muscle systems
limiting factor = legs - low mito capacity
what effect does training have on resp system
very little effect
- last stage that adapts for exercise (very little adaptation)
- lungs end up as the limiting factor
