A&P2 Week 6: Pulmonary Ventilation

Pulmonary Ventilation

• Defined as breathing; involves inhalation (inflow) and exhalation (outflow) of air between the atmosphere and the alveoli.

External Respiration

• The exchange of gases between the alveoli and blood in pulmonary capillaries across the respiratory membrane.
• Oxygen (O₂) enters the blood, while carbon dioxide (CO₂) is expelled.

Internal Respiration

• The exchange of gases between blood in systemic capillaries and tissue cells.
• Blood loses O₂ and gains CO₂; cellular respiration occurs within cells, consuming O₂ and producing CO₂ during ATP production.

Differences between Pulmonary Ventilation, External and Internal Respiration

• Pulmonary ventilation entails breathing (air influx and efflux).
• External respiration is gas exchange at the alveoli level (O₂ in, CO₂ out).
• Internal respiration occurs at the tissue level (O₂ out of blood, CO₂ in).

Boyle's Law

• States that the pressure of a gas in a closed container is inversely proportional to the volume of the container.
• Increasing container size decreases gas pressure; decreasing container size increases gas pressure.

Lung Volume and Air Movement

• Variations in lung volume create pressure differences that drive air into the lungs during inhalation and out during exhalation.

Increasing Volume

• Inhalation occurs when lung volume increases and lung pressure decreases, leading to air moving into the alveoli where atmospheric pressure is higher.

Decreasing Volume

• Exhalation happens when lung volume decreases and lung pressure increases, causing air to move from the alveoli to the external atmosphere where pressure is lower.

Alveolar Pressure Changes

• As the diaphragm flattens and intercostal muscles contract, lung volume increases and pressure decreases, facilitating inhalation.

Expiration as a Passive Process

• Refers to exhalation as a passive process because it occurs without muscular contractions.

Alveolar Pressure During Muscle Relaxation

• When muscles relax and the lungs recoil, lung volume decreases and pressure increases, leading to exhalation.

Quiet versus Forceful Pulmonary Ventilation

• Quiet inspiration involves the diaphragm and external intercostal muscles contracting, slightly enlarging the thoracic cavity.
• Deep breathing incorporates forceful contractions of inspiratory muscles and accessory muscles, achieving larger volume changes during inspiration and expiration.

This quiz covers key concepts related to pulmonary ventilation and external respiration. It defines important terms such as breathing and gas exchange within the lungs. Test your understanding of these fundamental respiratory processes.