Lab Exam 2- Lab 10 Flashcards
acute ascent to altitude results in
environmental hypoxia
the reduction in the amount of oxygen at altitude is due to
reduced barometric pressure at increasing altitudes
the lower barometric pressure reduces the
partial pressure of inspired O2 (PiO2)
hypobaric hypoxia
the hypoxia associated with terrestrial altitude exposure
does the percentage of O2 in ambient air change at altitude
NO- the %O2 in ambient air is always constant at 20.93% regardless of altitude
physiological responses to altitude are dependent on
the severity of hypoxia
if a sea level resident travelled to Mount Everest what physiologic changes would be seen
loss of consciousness within minutes to hours
what happens physiologically to a person with gradual ascent and chronic altitude exposure
physiological adaptations - acclimatization
enables us to successfully tolerate altitudes that would cause major problems acutely
what condition is focused on in the altitude lab
acute hypoxia
what 3 parameters are required to calculate PiO2
barometric pressure (Pb)
water vapor pressure (PH2O) in inspired air
% of O2 in the environment
barometric pressure is dependent on
altitude
water vapor pressure in inspired air (PH2O)
47 mmHg *** independent of altitude
% O2 in the environment
20.93% *** independent of altitude
equation to calculate PiO2
PiO2= (Pb-PH2O) * %O2(as a decimal)
or
PiO2= (Pb-47)*0.2093
how does an acute reduction in PiO2 affect O2 levels in the blood
reduced PiO2 leads to a decrease in alveolar partial pressure of O2 (PAO2) which leads to a reduction in the partial pressure of O2 in arterial blood (PaO2)
what does SaO2 stand for
arterial Hb-O2 saturation
what is a major determinant of arterial hemoglobin O2 saturation (SaO2)
PaO2
shape of O2-Hb saturation curve
sigmoidal
at the top of the O2-Hb saturation curve, what is the effect of small changes in PaO2
minimal effect
at the steep portion of the O2-Hb saturation curve, what is the effect of small changes in PaO2
large effects on SaO2
arterial oxygen content (CaO2) is determined by 3 parameters
[Hb]
SaO2
amount of O2 dissolved in plasma
PaO2 influences ____
SaO2 and determines the amount of O2 dissolved in plasma
compare the amount of O2 dissolved in plasma vs bound to Hb
the amount of O2 dissolved in plasma is extremely small compared to the amount bound to Hb
in this weeks lab what are we examining
the changes in SaO2 heart rate, ventilation, BP, and substrate utilization at rest and during submaximal exercise with stimulated altitude exposure
*we are simulating high altitude using normobaric hypoxia
what does PaO2 stand for
partial pressure of O2 in arterial blood
what does CaO2 stand for
arterial O2 content
physiological response to acute altitude exposure
decrease in PaO2, SaO2, and CaO2
acute altitude exposure effects on max O2 uptake
VO2max is reduced with acute altitude exposure, with the severity of the reduction greater at higher elevations
% reductions in VO2 max: trained vs untrained
endurance trained athletes have a higher % reduction in VO2 max than untrained individuals
the decrease in VO2max at acute altitude exposure does what to intensity
increases the relative intensity of any given absolute (submaximal) power output at altitude
HR response to acute altitude exposure
an increase in resting HR and elevation in HR at any given absolute submaximal power output
what happens to max HR with acute altitude exposure
no change
what are the main factors in the blood influencing ventilation rate at sea level
PaCO2 and arterial pH
*peripheral chemoreceptors that reside in aortic/carotid bodies respond to low PaO2 and play a predominant role in ventilatory response to hypoxia
the fall in PaO2 at altitude results in
an increase in ventilation at rest and all absolute workloads compared to sea level
compare the increase in ventilation during exercise at altitude vs at rest
the increase in ventilation during exercise at altitude is significantly larger than the increase in ventilation at rest
substrate utilization response to acute altitude exposure
increases CHO utilization during absolute submaximal exercise intensities
BP response to acute altitude exposure
MAP may decrease slightly
- although increase in SNS activity with acute altitude exposure are expected to contribute to peripheral vasoconstriction, local factors are released that blunt peripheral vasoconstriction leading to small reductions in TPR and BP
variability in individuals response to acute altitude exposure
the level of hypoxia incurred at a given altitude varies between individuals
normobaric hypoxia
simulating altitude without going to altitude
*artificially modifying the %O2 by providing subjects with a hypoxic (<20.93%) gas mixture in lab setting
pressure = normal but the PiO2 is reduced due to artificial reduction in the % inspired O2
2 conditions measured in this lab
normoxic exercise and hypoxic exercise at two different submaximal workloads - 50 W and 100 W
what variables are measured at rest
BP
HR
Ve
O2 saturation
what variables are measured during normoxic/hypoxic exercise
BP
HR
VE
O2 saturation
RPE
how long are subjects exercising at each submaximal workload
4-5 minutes
how long will the subject rest for before starting exercise
10 minutes
during the hypoxic protocol, what is the components of the air breathed in made of
15% O2 / 85% N2 gas simulating the hypoxic condition experienced at Pikes Peak (4300 m, 14,110 ft above sea level)
hypoxic conditions effect in VT / LT thresholds
cause a leftward shift
VT and LT are reached at lower absolute workloads during hypoxic exercise
hypobaric hypoxia
reduce pressure in hypobaric chamber
normobaric hypoxia
reduce fraction of O2 in inspired gas
