Final answer:
During inhalation, the diaphragm and external intercostal muscles contract to draw air into the lungs. Normal exhalation is a passive process involving relaxation of these muscles, while forced exhalation also recruits the internal intercostals and abdominal muscles.
Step-by-step explanation:
Muscles Involved in Inhalation and Exhalation
The muscles involved during inhalation primarily include the diaphragm and the external intercostal muscles. The diaphragm contracts and moves downward, while the external intercostals contract to lift the ribs upward and outward, expanding the thoracic cavity and reducing the air pressure inside the lungs, drawing in air. Normal exhalation is mostly a passive process where these muscles relax, and the lungs recoil due to their elastic nature, increasing air pressure inside the lungs and pushing air out. During forced expiration, additional muscles such as the internal intercostals and the abdominal muscles contract to forcefully expel air from the lungs.
Inhalation Muscles
- Diaphragm
- External intercostal muscles
Exhalation Muscles (Forced)
Internal intercostal muscles
In conclusion, the muscles involved in inhalation and exhalation facilitate the movements of air in and out of the lungs, accommodating the changes in pressures necessary for respiration.
This creates a lower pressure within the lung than that of the atmosphere, causing air to be drawn into the lungs. During expiration, the diaphragm and intercostals relax, causing the thorax and lungs to recoil. The air pressure within the lungs increases to above the pressure of the atmosphere, causing air to be forced out of the lungs. How