lab 10 Flashcards
What happens to the partial pressure of inspired oxygen (PiO2) if the barometric pressure is lower
reduced partial pressure of inspired oxygen
Hypoxia is associated with what exposure and what is the name for it?
associated with terrestrial altitude exposure called hypobaric hypoxia
what happens that enables us to successfully tolerate altitudes that would cause major problems acutely
physiological adaptations –> acclimatization
What is the percentage of oxygen in ambient air? is this effected with altitude
20.93% ALWAYS and not effectitude by altitutde
What are the responses with acute exposure to Boulder’s altitude
some physiological responses but magnitude of response is much less than compared to a higher altitude (pikes peak or mt. everest)
How do you calculate PiO2 and what are the individual factors
PiO2 = (Pb - PH2O) (% oxygen as decimal)
Pb = barometric pressure dependent on altitude
PH2O = 47mmHg, independent of altitude
percent of O2 in the environment = 20.93%, independent of altitude (unless told given 100% O2)
How does an acute reduction in PiO2 affect oxygen levels in the blood
Reduced PiO2 leads a decrease in alveolar partial pressure of oxygen (PAO2) –> reduction in partial pressure of oxygen in arterial blood (PaO2)
What is PaO2
major determinant of arteral hemoglobin O2 saturation (SaO2)
Explains what happens in the hemoglobin oxygen dissociation curve
curve is sigmoidal
* near top of curve small changes in PaO2 ahve minimal effect on SaO2
* PaO2 falls to steeper part of curve, sm. changes in PaO2 have large effects on SaO2
What is the symbol for arterial oxygen content
CaO2
arterial oxygen content is determined by what 3 parameters
- hemoglobin concentration
- SaO2
- amount of O2 dissolved in plasma
How does PaO2 influence SaO2 and determines what
influences SaO2 and determines the amount of O2 dissolved in the plasma
Is there more mL of O2 per liter of arterial blood dissolved in plasma or bound to hemoglobin
- ~3mL of O2 dissolved in plasma
- ~197mL O2 per L of bound to hemoglobin
What occurs physiologially in response a decrease in PaO2, SaO2, and CaO2
response in cardiovascular, respiratory, and immune systems –> influence substrate utilization
What is reduced with actue altutitude exposure and reduction gets greater at higher elevations
VO2max
How is VO2 effected between trained and untrained undividuals at higher altitudes
VO2 is lower for trained individuals than untrained at higher altitudes becasue their SV is greater –> less pulmonary capillary time –> less oxygenation consumption
Explain how acute altitude exposure effects resting HR? how is maxHR effected
increase in resting HR and elevation in any HR at given submax power output
* HRmax is unaltered
What are the primary factors in teh blood influencing ventilation rate
PaCO2 and arterial pH
What part of the body responds to low PaO2 and plays a dominant role in ventilation response to hypoxia
peripheral chemoreceptors in the aorta and corotid bodies
the fall in PaO2 at altitude does what to ventilation at rest and other workloads
fall in PaO2 increases ventilation at rest and all workloads compared to sea leave
acscent to high altitude increases what type of substrate utilization during absolute submax exercise intensities
increases in CHO utilization
What happens to MAP with acute altitude response
MAP decreases slightly with acute altitude response
Why does MAP decrease in altitude
- increase in SNS activity w/ acute altitude exposure –> peripheral vasoconstriction
- small reductions in total peripheral resistance and BP
What is an important principle in understanding altitude with different people
there is large variability in the magnitude of physiological responses
* large differences in SaO2
What happens to the percent of oxygen in ambient air when going to altitude
constant regardless of altitude
- unless given artifiical gas mixture in lab setting
what is normobaric hypoxia
when the percentage of O2 can be artifically modified by providing subjects with a hypoxic (<20.93%) gas mixture in the lab
* pressure is normal but the PiO2 is reduced due to artifiicl reduction in the percentage of inspired O2
What is:
* PaO2
* SaO2
* CaO2
- PaO2 = partial pressure of oxygen
- SaO2 = arterial oxygen saturation
- CaO2 = arterial oxygen content (number of O2 molecules in the arterial blood)
What decreases in relation to oxygen in the atmosphere at altitude
partial pressure of oxygen PO2 (mmHg) in the air decreases
What is PiO2
partial pressure of inspaired air
how does lower barometric pressure effect PiO2
reduces the PiO2
Explain the complete oxygen transport cascade
- atmospheric air -(goes into lungs b/c lower PP)-> airway gas (dilution by CO2
- airway gas transported to alveolar gas because of diffusion b/c alveoli are at a lower partial pressure
- alveolar gas gets transported to endcapillary blood because lower partail pressure (venous mixture)
- endcapillary blood gets moved to artierl blood
- arterial blood through diffusion goes to the tissue that has a lower partial pressure of oxygen
- in the tissue oxygen is transported to the mitochondria where they have the lowest. partial pressure of oxygen
reduced PiO2 leads to a decrease in ___ which leads to a reduction in ___
reduced PiO2 leads to a decrease in __alveolar partial pressure (PAO2)__ which leads to a reduction in __partial pressure of oxygen in arterial blood (PaO2)_
What is the physiological response in saturation with acute altitude response
decreases arterial oxygen aturation
* sigmoidal curve shifts left?
Explain what the pathway is starting with acute hypoxia to 4 major factors from more epinephrine released
Acute Hypoxia –> decreased PiO2 –> decreased PaO2 –> adrenals impacted –> increased release of epinephrine
- increased HR, increased SV, increased cardiac output
- change in substrate metabolism (CHO, fat)
- increase vasodilation –> slight decrease in MAP
- increase resting metabolic rate
how are the Tvent and LT shifted due to hypoxic conditions
leftward shift becuase reached at a lower absolute workload
Explain the two conditions in which you can stimulate altitude in the laboratory
- hypobaric hypoxia: reduce pressure in hypobaric chamber
- normobaric hypoxia: reduce fraction of oxygen in the inspired gas
