ventilation and ventilatory thresholds Flashcards
mechanism of respiratory regulation
central chemoreceptors - stimulated by increased co2 in cerebrospinal fluid
increased rate and depth of breathing
remove excess co2 from body
peripheral chemoreceptors- in artic bodies + carotid bodies
sensitive to blood po2, pco2 , H+
location of carotid and aortic bodies
located on carotid artery and aorta
carotid- can detect if there is low o2 going to brain
aorta- can detect if there is low o2 near heart
ventilatory drive at altitude
ventilation is increased when po2 has decreased
less o2 at altitude so need to breathe more in order to gain the same volume of oxygen
increased breathing rate is to get rid of co2
regulation of pul ventilation
body must maintain homeostatic balance of blood po2, pco2 and pH
requires coordination between resp and CV systems
ventilation and acid base balance
harder the exercise, more H+- anaerobic metab
pulmonary ventilation can help remove H+ from blood
bicarbonate is one of many buffers- inc PC, proteins, phosphate, but co2 is only product of bicarbonate
exhaling co2 gets rid of protons, increasing the pH- less acidic
ventilation and pH
ventilation directly impacts pH
increased ventilation results in co2 exhalation- reduced blood pco2 and H+ concentration (ph increases)
decreased ventilation results in build up of co2- increased blood pco2 and H+ conc (ph decreases)
ventilatory thresholds
point during exercise when ventilation increases disproportionately to o2 consumption
due to venous blood pco2 increase and needs removing
increase in breathing is not due to needing more o2
aerobic ventilatory threshold
VT1- excess co2
determination of the aerobic ventilatory threshold- VT1- using the V slope method
at start of exercise, increase in o2 followed by similar increase in co2
as exercise continuies, for each o2 molecuke breathed in, more co2 molecules are breathed out
at this point, you start to breathe more- increased ventilation- VT1
ventilatory equivalent for o2
ratio between ventilation (ve) and vo2
ve/vo2= ventilatory equivalent
VE equivalent for o2
ve/vo2 remains relatively constant over a wide range of submaximal intensities and starts to increase at the aerobic ventilatory threshold because o2 demand keeps increasing linearly whilst there is a break point in Ve
respiratory compensation point
RCP or VT2
maximal lactate steady state (MLSS) - highest intensity at which lactate production=lactate removal
at higher intensities, progressive lactate accumalation and enhanced co2 prod- more protons= more buffers=more co2
ventilation further increased
second break point in ventilation curve- respiratory compensation point
determining RCP
up to RCP, ventilation increases linearly with co2
after RCP, even more pronounced hyperventilation (lower co2 output per L of exhaled air)
no change in ratio up until this point
increased ventilation but co2 does not follow suit
ventilation during hard exercise
Co2 accumalation may not be the main reason for increased ventilation at high exercise intenstities
- increases in core temp
- potassium
- mechanical receptors in muscles
VT notes
VT may be affected by the above and may hence not occur at the same intesnsities as their corresponding lactate thresholds questions whetehr lactate and VT are mechanically linked at all
BL vs VT
usually found in close proximity- similar exercise domain
lactate turnpoint (MLSS) and RCP occur in a similar place
