Ventilation During Exercise

Question 1

What are the changes during exercise for TV, frequency, and ventilation rate?

Answer 1

• *Tidal Volume** – Rapid increase from first workload
• *Frequency** – Barely changed during first workload, increased during second, further increase during third
• *Ventilation Rate** – Rapid increase during first workload

Question 2

What are the differences in inhaled and exhaled air?
How does this change during exercise?
How does this chnage with increased airway resistance?

Answer 2

Inhaled air is 21% oxygen, 0% carbon dioxide
Exhalation is 15% oxygen, 6% carbon dioxide

Exercise has a minimal effect on values, indicating that alveolar ventilation has increased in proportion to the increase in metabolic rate

Increased resistance results in:
Oxygen decreases, more carbon dioxide supply
Greater metabolic demand but effective less supply

Question 3

How does alveolar to capillary gas exchange change during exercise?

(Diffusing capacity and ventilation)

Answer 3

Increase in alveolar to capillary gas exchange is indicated by the increase of diffusing capacity: Due to recruitment of alveolar-capillary units which increases the surface area for gas exchange

Body needs to eventually hyperventilate once demand gets too high:
Increases alveolar oxygen, so increased driving pressure
No change in diffusing capacity

Question 4

What are the components for temporal pattern of ventilation signaling during exercise?
What is the source of each of these sources?

Answer 4

Suggest signal for hyperpnea must have both a fast and a slow component

Fast component postulated to reflect from the hypothalamic motor areas (central control)
Slow component might be due to feedback from muscles (chemokines)
**Neither of these explanations are definitive **