Lab 10 Flashcards
What is hypobaric hypoxia
Hypoxia associated with terrestrial altitude exposure
What is the percentage of oxygen in ambient air
20.93%
What is PiO2 at Everest, Pikes Peak, Boulder (~1630 m), and sea level
43, 86, 122, and149 mmHg
What allows people do undergo physiological adaptations in response to altitude
Gradual ascent and chronic exposure
What 3 parameters are needed to calculate PiO2
Barometric pressure (Pb)*, water vapor pressure of inspired air (47 mmHg), and percentage of oxygen in the environment (20.93%)
*Only factor that is dependent on altitude
What is the equation for PiO2
PiO2 = (Pb - PiH20) * %oxygen
What effect does a reduction in PiO2 have
It reduces alveolar O2 pressure (PAO2) which then reduces arterial O2 pressure (PaO2), which then decreases arterial hemoglobin saturation (SaO2)
What is the major determinant of arterial hemoglobin saturation (SaO2)
Arterial pressure of oxygen (PaO2)
What 3 parameters determine arterial oxygen content (CaO2)
Hemoglobin concentration [Hb], hemoglobin saturation (SaO2), and the amount of O2 dissolved in the plasma
For a typical male at sea level, how much oxygen is dissolved in their plamsa compared to bould to hemoglobin
~3mL O2 / L arterial blood compared to 197 mL O2 / L arterial blodd
What effect does acute altitude exposure have on VO2max
It decreases VO2 max (with trained endurance athletes experiencing a steeper decrease) which increases the relative intensity of any submaximal absolute power output
What effect does acute altitude exposure have on heart rate
It increases HR at any submaximal intensity but doesn’t effect HRmax
What effect does acute altitude exposure have on ventilatory threshold
Ventilation increases at rest and significantly at all submaximal intensities (bc/ peripheral chemoreceptors in aortic and carotid bodies prioritize change in PaO2)
What effect does acute altitude exposure have on substrate utilization
Carb utilization at altitude increases at submaximal intensities
What effect does acute altitude exposure have on BP
MAP may decrease slightly bc/ peripheral vasoconstriction due to SNS is combatted by local factors
What is one variable that varies a lot between subjects at altitude
Hypoxic ventilatory response
What is normobaric hypoxia
An artifical way to stimulate hypoxia by keeping the partial pressure of O2 constant but altering the concentration of it in ambient air (<20.93%)
During lab 10, what is the concentration of gases in the hypoxic mixture
15% O2 / 85% N2 (stimulates Pikes Peak or 4300 m above sea level)
What is the protocol for lab 10 (altitude lab)
1) Resting for 10 mins, measurements made in last min
2) Working out at 50W, measurements made in last min
3) Working out at 100 W, measurements made in last min
*First workout is either hypoxic or normoxic and then switch
What 5 measurements will be taken in lab 10
HR, BP, Ve, O2 saturation, and *RPE
*Only when exercising
