Unit-2 chapter- 1 Pg:- 41,42
Ventilation in the lungs, also called breathing, is the process of moving air in and out of the lungs. This constant airflow is essential for gas exchange, bringing in fresh oxygen (O2) and removing waste carbon dioxide (CO2) from the body.
The Players: The main muscles involved in ventilation are the diaphragm and the intercostal muscles between the ribs.
Inspiration (Inhaling): When you inhale, the diaphragm contracts and moves down, enlarging the chest cavity. At the same time, the intercostal muscles pull the ribs upward and outward, further increasing the chest volume. This creates a negative pressure (lower pressure than the outside air) within the lungs. As a result, air rushes in through your nose and mouth, filling the expanded lungs.
Expiration (Exhaling): When you exhale, the diaphragm and intercostal muscles relax. The chest cavity recoils back to its resting size due to the natural elasticity of the lungs and chest wall. This pushes air out of the lungs. Expiration is usually a passive process, but during heavy exercise, additional muscles may help force air out more forcefully.
Pressure Gradients:
The key to ventilation is the creation of pressure differences between the lungs and the atmosphere. During inhalation, the negative pressure in the lungs draws air in. During exhalation, the pressure in the lungs becomes slightly positive compared to the outside air, forcing air out.
Gas Exchange:
Ventilation allows fresh air to reach the tiny air sacs in the lungs called alveoli. Here, oxygen from the inhaled air diffuses into the bloodstream, while carbon dioxide waste from the blood diffuses into the alveoli to be exhaled.
Points:
The rate and depth of ventilation can change depending on your body's needs. During exercise, your body requires more oxygen, so you breathe faster and deeper to increase air intake.
Several factors can affect ventilation, such as lung diseases, injuries to the chest wall, and even high altitude, where there's less oxygen in the air.