Explain the Mechanics of Respiration
The mechanics of respiration refer to the physical processes involved in breathing—inhalation and exhalation. It involves the coordinated activity of the respiratory muscles and changes in thoracic volume and pressure.
1. Inhalation (Inspiration)
- The diaphragm contracts and flattens, increasing the vertical dimension of the thoracic cavity.
- External intercostal muscles contract, raising the rib cage and expanding the chest laterally and anteroposteriorly.
- This expansion lowers the intrathoracic pressure below atmospheric pressure, causing air to flow into the lungs.
2. Exhalation (Expiration)
- Normally a passive process.
- Diaphragm and external intercostals relax, returning the thoracic cavity to its original volume.
- Increased pressure in the thoracic cavity forces air out of the lungs.
- In forced exhalation, internal intercostals and abdominal muscles help expel air actively.
3. Compliance and Resistance
- Compliance: The ability of the lungs to expand. High compliance means easier lung inflation.
- Airway Resistance: Resistance in air passages affects airflow; it increases in conditions like asthma.
In summary, the mechanics of respiration involve muscle activity and pressure changes that enable air to move in and out of the lungs efficiently.