Summary of Mechanism of Breathing, Animation

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This video explains how the respiratory system functions and how Pulmonary ventilation is achieved by rhythmically changing the volume of the thoracic cavity. It also discusses how deep breathing requires more forceful contractions of the diaphragm, intercostal muscles, and involves additional muscles to produce larger changes in the thoracic volume.

• 00:00:00 The video explains how the respiratory system functions, including the principles of gas laws which govern the flow of air. At rest, the pressure within the lungs equals the pressure outside the body, or atmospheric pressure. When discussing respiratory pressures, this is generally referred to as a relative pressure of zero. Pulmonary ventilation is achieved by rhythmically changing the volume of the thoracic cavity. During inspiration, the diaphragm and the external intercostal muscles contract, expanding the thoracic cavity and the lungs. This increase in volume results in a decrease in pressure, causing outside air to flow in. Another factor that helps to inflate the lungs is the warming of the inhaled air. Quiet expiration relies on the elasticity of the lungs and rib cage - their ability to spring back to the original dimensions. Conditions that reduce pulmonary elasticity, such as emphysema, can cause difficulty exhaling. Deep breathing requires more forceful contractions of the diaphragm, intercostal muscles, and involves additional muscles to produce larger changes in the thoracic volume. Deep expiration, unlike quiet expiration, is an active process. Lung compliance is reduced when the lungs become “stiff”, in conditions that cause scarring of lung tissues, or fib