Expiration

Expiration is the process of expelling air from the lungs. In humans and many other animals, it is a part of the respiratory cycle. The process of expiration is vital for respiration, as it allows for the removal of carbon dioxide, a waste product of cellular respiration, from the body.

Process

During expiration, the diaphragm and intercostal muscles relax, causing the chest cavity to decrease in volume. This decrease in volume causes an increase in pressure in the chest cavity relative to the outside air. As a result, air flows out of the lungs and into the atmosphere, expelling carbon dioxide from the body.

Factors affecting expiration

Several factors can affect the process of expiration, including lung elasticity, airway resistance, and lung volumes and capacities. Diseases such as COPD and Asthma can also affect expiration.

Lung elasticity

The elasticity of the lungs refers to their ability to return to their original size after being stretched or compressed. If the lungs lose their elasticity, as in the case of Emphysema, the process of expiration can become difficult.

Airway resistance

Airway resistance is the resistance to the flow of air through the respiratory tract during inhalation and expiration. Increased airway resistance, as seen in conditions such as asthma, can make expiration more difficult.

Lung volumes and capacities

Lung volumes and capacities refer to the amount of air in the lungs at different phases of the respiratory cycle. Conditions that reduce lung volumes and capacities, such as Pulmonary Fibrosis, can affect expiration.

See also

• Respiration (physiology)
• Inhalation
• Breathing

References

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