Ch 10 Part 2 study questions

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Simon Fraser University
Biomedical Physio & Kines
BPK 205
Parveen Bawa

34. Compare and contrast the stimuli and rate of response of central and peripheral chemoreceptors. • 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 why? • Ventilation rate (lungs, CO2 levels), and Metabolic factor (kidneys, HCO3- levels) • 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- base disturbances. • 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 maintained 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 physiological mechanisms. 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 receptors • This will result in increased tidal volume, decreased breathing frequency 44. Draw the power duration for leg muscle and respiratory muscle on the same graph. 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 minute • At exhaustion there is bronchiole dilation that increases ventilation rate. MBC test done at rest doesn’t account for this exercise induced response 47. With respect to the flow rate-lung volume relation, why are normal, obstructive, and restrictive responses different? • Obstructiv
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