Pulmonary Function During Exercise Flashcards
what can cause the partial pressure v. hemoglobin saturation curve to shift to the right?
increased acidity
increased temperature
what happens when the partial pressure v. hemoglobin saturation curve shifts to the right?
lower affinity of hemoglobin for oxygen
oxygen offloaded more easily
does myoglobin release oxygen easily at high concentrations of oxygen?
no
when is myoglobin important?
transporting oxygen to the mitochondria at the beginning of exercise and during very strenuous exercise
what happens to PaCO2, PaO2, and pH during strenuous exercise in most animals?
remain normal
what enzyme allows the interconversion of bicarbonate and CO2?
carbonic anhydrase
what determines ventilatory control?
input from respiratory center in medulla
chemical state of blood as it communicates with medulla
plasma PaO2, PaCO2, H+ concentrations
chemoreceptors
where are the sensors of PaO2?
aortic bodies at arch of aorta
carotid bodies at branching of carotid arteries
what is the most important stimulus to ventilation?
partial pressure of CO2 in plasma
why does ventilation increase in exercise out of proportion to PaCO2?
cortical input
peripheral input from mechanoreceptors
what happens during steady rate, aerobic exercise, with ventilation and oxygen uptake?
ventilation increases as oxygen uptake does
what happens when exercise intensity increases?
eventually, tissue demand outstrips the combined respiratory and cardiovascular ability to supply oxygen
anaerobic component, lactate and tissue CO2 rise
what does VO2 refer to?
amount of oxygen an individual can take up at any given time
where does blood go preferentially in the lungs of a horse?
dorsal regions
what do horses have that is unprecedented?
pulmonary hypertension
reaches close to 100mmHg at a gallop
what are the five basic mechanisms of hypoxemia?
decrease in inspired FiO2
right to left shunts
V/Q mismatching
diffusion impairment
alveolar hypoventilation
why do horses experience hypoxia and hypercapnea during exercise?
hypoventilate
diffusion impairment
when does the precipitously steep portion of the oxygen-hemoglobin binding curve occur?
PaO2 of 60mmHg
if we breathe in a gas with a higher percentage of O2, what happens to our minute ventilation?
slows down
why do we breathe with a greater rate during exercise?
greater minute ventilation
likely dissipates heat
what increases in the CSF when CO2 is increased?
H+
what does the ventilatory equivalent for oxygen tell us?
efficiency of ventilation: how many liters of air for every liter of oxygen you consume
what contributes most to VO2max?
heart
capillarization of muscle
density of mitochondria
not respiratory system
when does breathing frequency and stride frequency become tightly coupled in horses?
canter
gallop
not walk/trot
what does lack of stride/breath coupling indicate in a horse?
respiratory disease
what might cause pulmonary hypertension in horses?
high left atrial pressures
what is inertance?
impedance to breathing that moving a column of air back and forth at increasing frequencies entails
what happens with resistance when a horse exercises?
it increases
how much does the work of breathing increase in a horse between rest and exercise?
almost 500-fold
what does it mean that horses’ work of breathing increases so much during exercise?
they may reach a point where increases in ventilation cost more in energy than the horse can afford while still performing mechanical work
