W3-L2: Breathing

Question 1

VE vs. VA
(alveolar ventilation)

Answer 1

𝑽𝑨
Ventilation that participates in gas exchange
- Will be lower than VE
- More effective alveolar ventilation with deep breathing vs. through increased bf

Question 2

What is Anatomical dead space?

Answer 2

Anatomical dead space is the portion of the respiratory system where air is present but no gas exchange occurs, including the trachea, bronchi, and bronchioles.

should = physiological dead space in a healthy human

Question 3

What is Physiological dead space?

Answer 3

Includes the anatomical dead space plus any alveolar space where gas exchange is impaired or not occurring, such as in areas of the lung with poor blood flow or damaged alveoli.

Question 4

What is Hyperventilation?

Answer 4

Increase in pulmonary ventilation that exceeds the O2 consumption and CO2 elimination needs of metabolism

Question 5

What is Hypoventilation?

Answer 5

Inadequate ventilation for the O2 consumption and CO2 elimination needs of metabolism

Question 6

What is Dyspnea?

Answer 6

Inordinate shortness of breath or subjective breathing distress

higher in females

Question 7

What is the Valsalva Maneuver?

Answer 7

• Closing of the glottis following a full inspiration while maximally activating expiratory muscles,
• this creates compressive forces that increase intrathoracic pressure above atmospheric pressure
• Occurs commonly in activities that require a rapid, maximum application of force for short duration

Question 8

What is the point of the Valsalva Maneuver?

Answer 8

Valsalva reduces return of blood to the heart because increased intrathoracic pressure collapses inferior vena cava that runs through the chest cavity

This compression decreases venous return to the heart, reducing the preload and subsequently the cardiac output.

arteries have muscles but veins do not

The Valsalva maneuver can be useful during exercise, particularly in weightlifting, as it stabilizes the core and increases intra-abdominal pressure, providing better support for the spine and allowing for safer and more effective lifting of heavy loads.

Question 9

What are Physiologic Consequences of Performing the Valsalva Maneuver?

Answer 9

Performing a prolonged Valsalva maneuver during static, straining-type exercise dramatically reduces venous return and arterial blood pressure

• Diminishes brainʼs blood supply, producing dizziness or fainting
• Once the glottis reopens and intrathoracic pressure normalizes, blood flow reestablishes with an “overshoot” in arterial blood pressure

Question 10

The body’s supply of O2 in ambient air depends on what 2 factors?

Answer 10

(1) concentration
(2) pressure

Question 11

What are the normal concentration of O2, CO2 and N2 in the air?

Answer 11

• O2 = 20.93%
• CO2 = 0.03%
• Inert gases (primarily N2) = 79.04%

Question 12

What is Dalton’s law?

Answer 12

the total pressure of non-reactive gases is equal to the sum of the individual partial pressures

Question 13

How can partial pressure be calculated?

Answer 13

Question 14

Air Pressure on Land

Air pressure = PO2 + PN2 + PCO2

• PO2 = 760 x 20.93% = 159.1 mmHg
• PN2 = 760 x 79.04% = 600.7 mmHg
• PCO2 = 760 x 0.03% = 0.2 mmHg

What happens at altitude?

Answer 14

What happens at altitude?

• Atmospheric Pressure = ~220mmHg
• PO2 = 220 x 20.93% = 46 mmHg
• Consequences

Question 15

What is tracheal air?
How does it affect PO2 and PCO2?

Answer 15

When air is inhaled, it becomes humidified as it passes through the trachea, adding water vapor to the mixture. The presence of water vapor exerts a partial pressure of 47 mmHg, which must be subtracted from the total atmospheric pressure (760 mmHg) to determine the partial pressures of the other gases.

Humidified air = 47 mmHg;
Total pressure becomes: 760 – 47 = 713 mmHg

PO2= 713 mmHg x 20.94%= 150
PCO2= 713 mmHg x 0.04%=0.3

Question 16

Alveolar air

How does it affect PO2 and PCO2?

Answer 16

% O2 and % CO2 changes to:
% O2 = 14.5
% CO2 = 5.5

Question 17

check all this in lecture again