34. Compare and contrast the stimuli and rate of response of central and
• Central Chemoreceptors:
o Stimuli: CO2 increase in Cerebrospinal fluid
o Rate of response: within 1 min of stimulus
• Peripheral Chemoreceptors:
o Stimuli: PaCO2 increase, PaO2 decrease, pH decrease, increase all
detected in the carotid bodies, and aortic arch
o Rate of response: within 2-3 breaths
35. Describe the Hering-Breuer inflation reflex.
• Inspiration causes increased air flow, and blood flow into pulmonary
vessels. This stretches pulmonary stretch receptors, inducing the Hering-
Breuer reflex. The reflex causes inhibition of inspiration, so that the
expiration phase can be commenced. It also increases breathing
frequency by shortening expiration phase too.
36. Compare and contrast the O2 and CO2 effects on ventilation.
37. From an acid-base perspective, what 2 factors is pH dependent upon and
• Ventilation rate (lungs, CO2 levels), and Metabolic factor (kidneys, HCO3-
• CO2 + H2O H2CO3 H+ + HCO3-
• Increased CO2 shifts equation right to produce more H+ and lower pH
• Increased HCO3- shifts it left to reduce H+ and raise pH
38. Describe in terms of speed and capacity only, the 3 systems that
compensate acid-base disturbances.
• Chemical system:
o ECF: Bicarbonate and Hb buffer, ICF: proteins, phosphates
o Speed: fastest
o Capacity: most limited
• Ventilation system:
o Increase/decrease ventilation; VCO2rate
o Speed: moderate
o Capacity: moderate
• Kidney System:
o Increase/decrease HCO2- excretion
o Speed: slowest
o Capacity: greatest 39. Describe 3 reasons why altering CO2 is good for compensating some acid-
• Changing CO2 levels affects H+ levels
• VArate is affected by PaCO2 so altering CO2 affects VArate
• PaCO2 changes outweigh PaO2 changes, so O2 homeostasis is
40.Be able to describe, with a Davenport diagram, all 4 acid-base disturbances
and their respective compensations.
41. Draw the 3 stages of ventilation that occurs when exercise starts from rest
and steps up to a moderate intensity. Also attribute their corresponding
42. What happens to ventilation and performance when HeO2 is inspired
rather than room air?
• Ventilation increases because it is easier for respiratory muscles to do
work. Due to HeO2 being less dense. Performance increases as a result
43. What happens to ventilation and respiratory pattern when inspired air is
laced with a local anaesthetic? Also describe the physiological mechanism
regulating this effect.
• The local anaesthetic inhibits stimulation of the pulmonary stretch
• This will result in increased tidal volume, decreased breathing frequency
44. Draw the power duration for leg muscle and respiratory muscle on the
45. What is the primary determinant of critical power?
• O2 delivery, and usage
46. Criticize the use of maximal breathing capacity for estimating the
contribution of a ventilatory limitation to fatigue.
• Doubtful that one can maintain that max 12 sec ventilation rate for a full
• At exhaustion there is bronchiole dilation that increases ventilation rate.
MBC test done at rest doesn’t account for this exercise induced
47. With respect to the flow rate-lung volume relation, why are normal,
obstructive, and restrictive responses different? • Obstructiv