Mechanism of Expiration
Explains the passive process of air expulsion (during normal breathing) involving muscle relaxation and a decrease in thoracic volume.
What is Mechanism of Expiration?
The pressure within the alveoli of the lungs.
Key points
- Explain the mechanism of normal expiration.
- Identify the muscles involved in expiration.
- Describe the changes in thoracic volume and pressure during expiration.
- Differentiate between passive and forced expiration.
Common exam trap
Confusing passive expiration with active expiration.
Definitions
- Term
Intrapulmonary Pressure
- Meaning
The pressure within the alveoli of the lungs.
- Term
Atmospheric Pressure
- Meaning
The pressure of the air surrounding the body.
- Term
Elastic Recoil
- Meaning
The tendency of an elastic structure, like the lungs and chest wall, to return to its original shape after being stretched or compressed.
Learning objectives
Explain the mechanism of normal expiration.
Identify the muscles involved in expiration.
Describe the changes in thoracic volume and pressure during expiration.
Differentiate between passive and forced expiration.
Prerequisites
Understanding of respiratory organs (lungs, thoracic cage).
Knowledge of diaphragm and intercostal muscles.
Concept of pressure gradients and airflow.
Common mistakes
Confusing passive expiration with active expiration.
Not understanding the role of elastic recoil.
Incorrectly assuming muscle contraction during normal expiration.
Keywords
Expiration
Breathing
Respiration
Passive process
Muscle relaxation
Elastic recoil
Thoracic volume
Intrapulmonary pressure
Atmospheric pressure
Diaphragm
Intercostal muscles
Practice preview
What happens to the volume of the thoracic cavity during normal exhalation?…
easy
Which of the following statements is TRUE regarding normal exhalation?…
easy
What is the relationship between intrapulmonary pressure and atmospheric pressure during normal exhalation?…
medium