Lab 10 Quiz

Question 1

Acute ascent to altitude results in

Answer 1

environmental hypoxia

Question 2

The reduction in the amount of oxygen with ascent to altitude is due to the reduced

Answer 2

barometric pressure at increasing altitudes which reduces the partial pressure of inspired oxygen (PiO2)
(ie. lower barometric pressure and pp of inspired oxygen)

Question 3

What is the hypoxia associated with terrestrial altitude exposure called

Answer 3

hypobaric hypoxia

Question 4

Percentage of oxygen in ambient air

Answer 4

20.93%
Constant regardless of altitude

Question 5

What are the physiological responses to altitude dependent on

Answer 5

the severity of hypoxia

Question 6

What is the partial pressure of inspired oxygen (PiO2) in Boulder vs sea level, Pikes Peak, and Mt. Everest

Answer 6

122 mmHg in Boulder (~1630m)
149 mmHg at sea level
86 mmHg at Pikes Peak
43 mmHg at Mt. Everest

Question 7

Magnitude of responses if a sea level resident traveled to Boulder’s altitude vs. Pikes peak or Mt. Everest

Answer 7

Acute exposure to Boulder’s altitude would cause some physiological responses but magnitude of responses is remarkably different than if acutely exposed to Pikes peak or Everest (acute exposure to PiO2 of 43 mmHg would lead to loss of consciousness within minutes to hours)

Question 8

What enables humans to successfully tolerate altitudes that would cause major problems acutely

Answer 8

With gradual ascent and chronic altitude exposure we can undergo physiological adaptations (acclimatization)

Question 9

In the altitude lab, we will focus exclusively on

Answer 9

acute hypoxia

Question 10

Three parameters required to caluculate PiO2

& whether each parameter is dependent on altitude

Answer 10

1. barometric pressure (Pb): dependent on altitude
2. water vapor pressure (PH2O) in inspired air: 47 mmHg, independent of altitude
3. percentage of oxygen in the environment: 20.93%, independent of altitude

Question 11

PiO2 equation

Answer 11

𝑷𝑰𝑶𝟐 = (𝑷𝒃 − 𝑷𝑯𝟐𝑶) × % 𝒐𝒙𝒚𝒈𝒆𝒏 (𝒂𝒔 𝒅𝒆𝒄𝒊𝒎𝒂𝒍)

Question 12

Find the PiO2 at sea level if the barometric pressure is 760 mmHg

Answer 12

PIO2 at sea level = (760 mmHg - 47 mmHg) * 0.2093 = 149 mmHg.

Question 13

Effect of an acute reduction in PiO2 on oxygen levels in the blood

Answer 13

Reduced PiO2 leads to a decrease in the alveolar partial pressure of oxygen (PAO2) which leads to a reduction in the partial pressure of oxygen in arterial blood (PaO2)

Question 14

The partial pressure of oxygen in artierial blood (PaO2) is the major determinant of

Answer 14

arterial hemoglobin O2 saturation (SaO2): how saturated (with oxygen) your RBCs are

Question 15

recall that the hemoglobin oxygen dissociation curve is sigmoidal; what does this mean for small changes in PaO2 at the top of the curve vs the steeper part of the curve

Answer 15

Near the top of the curve, small changes in PaO2 have a minimal effect on arterial hemoglobin O2 saturation (SaO2)
On the steeper part, small changes in PaO2 have a large effect on SaO2

Question 16

arterial oxygen content (CaO2) is determined by what three parameters

& what influences two of the them

Answer 16

1. hemoglobin concentration
2. arterial hemoglobin O2 saturation (SaO2)
3. amount of oxygen dissolved in plasma

PaO2 influences SaO2 and determines the amount of oxygen dissolved

Question 17

Amount of oxygen dissolved in plasma compared to amount bound to hemoglobin

Answer 17

the amount of O2 dissolved in plasma is extremely small compared to the amount bound to hemoglobin. For ex: for a male at sea level, ~3 mL of O2 per liter of arterial blood are dissolved in plasma, whereas ~197 mL O2 per liter of arterial blood are bound to hemoglobin.

Question 18

The decrease in these three things with altitude exposure result in physiological responses

Answer 18

PaO2, SaO2, and CaO2

Question 19

The decrease in PaO2, SaO2, and CaO2 with altitude exposure results in physiological responses in what areas

Answer 19

physiological responses in the cardiovascular, respiratory, and immune system and influences substrate utilization

Question 20

During the altitude lab, we will examine changes in what 5 parameters

Answer 20

1. SaO2
2. HR
3. Ventilation
4. Blood pressure
5. Substrate utilization

Question 21

What are the two overall conditions at which we will be examining changes to parameters

Answer 21

at rest and during submaximal exercise with simulated altitude exposure

Question 22

Effect of altitude exposure on VO2max

Answer 22

VO2max is reduced with acute altitude exposure; greater reduction at greater altitudes

Question 23

Reductions in VO2max in edurance training athletes vs untrained subjects

Answer 23

percent reductions in VO2max are greater in endurance trained athletes compared to untrained subjects
In trained athletes, reductions in VO2max have been reported at as low as 580m (1900 feet) above sea level

Question 24

VO2max and relative intensity at altitude

Answer 24

The decrease in VO2max increases the relative intensity of any given absolute (submaximal) power output at altitude

Question 25

Effect of altitude exposure on heart rate

Answer 25

Acute altitude exposure results in an increase in resting HR and an elevation in HR at any given absolute submax power output

BUT Maximal HR is unaltered

Question 26

Primary factors in the blood influencing ventilation rate at sea level vs those at altitude/during hypoxia

Answer 26

at sea level, factors influencing ventilation rate = PaCO2 and arterial pH

at altitude/hypoxia, chemoreceptors in the aortic and carotid bodies respond to low PaO2 & play the predominant role in ventilatory response

Question 27

Effect of drop in PaO2 on ventilatory rate

Answer 27

The fall in PaO2 at altitude results in an increase in ventilation at rest and all absolute workloads compared to sea level.
The increase in ventilation during exercise at altitude is significantly larger than the increase in ventilation at rest.

Question 28

Effect of altitude on substrate utilization

Answer 28

ascent to high altitude increases carbohydrate utilization during absolute submax exercise intensities

Question 29

Effect of altitude on blood pressure

Answer 29

• Mean arterial pressure may decrease slightly
• Small reductions in total peripheral resistance and blood pressure due to local factors that blunt the peripheral vasoconstriction caused by sympathetic NS activity

Question 30

Individual variability at altitude

Answer 30

the magnitiude of physiological responses and the level of hypoxia incurred at a given altitude varies between individuals

Question 31

How can we simulate altitude without going to altitude

Answer 31

Normobaric hypoxia: normal pressure but reduced fraction of oxygen in the ispired gas (PiO2)

the percentage of oxygen can be artifically modified by providing subjects with a hypoxic (<20.93%) gas mixture

Question 32

Hypoxic protocol

Answer 32

student will be breathing a 15% O2/ 85% N2 gas mixture that simulates the hypoxic condition experienced at Pikes Peak (4300 m, 14,110 ft above sea level)

Question 33

What are the effects of acute altitude exposure on the 5 parameters we’re examining (SaO2, HR, Ventilation, BP, and Substrate utilization)

what about oxygen uptake?

Answer 33

1. Decreased SaO2
2. Increases resting and submax HR (HRmax = same)
3. Increased ventilation
4. Slight decrease in MAP
5. Increased CHO utilization

Decreased VO2max

Question 34

Name of the hypoxia associated with terrestial altitude exposure vs. the one we use in lab

Answer 34

• Hypobaric hypoxia: reduced pressure (can also be recreated in lab using hypobaric chamber)
• Normobaric hypoxia: reduced fraction of oxgyen in the inspired gas

Question 35

What are the two submax workloads during the exercise conditions

Answer 35

50W and 100W

Question 36

6 different conditions and what we’ll be measuring at each

Answer 36

1. Rest hypoxia (10 min): BP, HR, VE, O2 sat
2. Rest normoxia (10 min): BP, HR, VE, O2 sat
3. Exercise hypoxia (5 min @ 50 watts): BP, HR, VE, O2 sat, RPE
4. Exercise hypoxia (5 min @ 100 watts): BP, HR, VE, O2 Sat, RPE)
5. Exercise normoxia (5 min @ 50 watts): BP, HR, VE, O2 sat, RPE
6. Exercise normoxia (5 min @ 100 watts): BP, HR, VE, O2 sat, RPE

Question 37

When are measurements collected during rest and exercise

Answer 37

During minute 9-10 if rest and minute 4-5 of exercise