Advanced Life Support (ALS) Level 3 (VTQ)

117 videos, 6 hours and 42 minutes

Course Content

Mechanics of respiration

Video 28 of 117
4 min 55 sec
Want to watch this video? Sign up for the course or enter your email below to watch one free video.

Unlock This Video Now for FREE

This video is normally available to paying customers.
You may unlock this video for FREE. Enter your email address for instant access AND to receive ongoing updates and special discounts related to this topic.

Understanding the Mechanics of Respiration

Nervous Control of Respiration

Respiration relies on various factors coming together harmoniously. One crucial element is the presence of an intact nervous system that governs respiratory functions. In the brainstem, specifically the medulla oblongata, lies the inspiratory centre, acting like a switch, alternating between on and off states. During the on-phase, signals are sent through the phrenic and intercostal nerves to the diaphragm and intercostal muscles. This contraction elevates the ribcage and straightens the diaphragm, creating a negative pressure in the lungs, facilitating inhalation. This cycle continues with two seconds on and three seconds off.

Mechanics of Respiration

Another essential aspect involves the mechanical components of respiration, including the rib cage, intercostal muscles, and diaphragm. All these components must function correctly to facilitate breathing. Any injuries or trauma to the chest or diaphragm can disrupt this mechanical process, even if nervous control is intact, highlighting the need for a seamless connection between both aspects.

The Role of the Environment

Furthermore, the environment plays a pivotal role. It must contain oxygen and allow it to reach the alveoli in the lungs. Any obstructions, such as foreign bodies, mucus, vomit, blood, or physical barriers, can restrict airflow, potentially leading to respiratory arrest. Maintaining an open airway is crucial for proper respiration.

Factors Affecting Respiratory Function

Several factors can affect respiratory function, particularly the nervous control:

  • 1. Drug Influence: Certain drugs, like heroin, can depress the respiratory centre, leading to a decreased respiratory rate.
  • 2. Trauma and Injury: Trauma to the neck or spinal nerves can disrupt the communication between the brain and respiratory muscles, causing malfunction.
  • 3. Mechanical Obstruction: Penetrating injuries or chest trauma can hinder the thoracic cage's ability to draw air into the lungs.


In summary, the process of respiration involves a complex interplay between nervous control, mechanical components, and environmental factors. Understanding this intricate system is vital for maintaining proper breathing and oxygenation of the cardiovascular system.

For a visual representation of respiration, please watch the accompanying animation.