What is the Mechanism of Breathing in Humans?
Human breathing, also known as pulmonary ventilation, is a fascinating interplay of muscle contractions and pressure changes that allows for the intake of oxygen-rich air and the expulsion of carbon dioxide-rich air. It's a continuous process crucial for sustaining life.
Breathing involves two main phases: inhalation (inspiration) and exhalation (expiration).
Inhalation (Inspiration)
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Diaphragm Contraction: The diaphragm, a dome-shaped muscle at the base of the chest cavity, contracts and flattens. This downward movement increases the volume of the chest cavity. [Reference: When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside. 02-Feb-2023]
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Intercostal Muscle Contraction: Simultaneously, the intercostal muscles (muscles between the ribs) contract, pulling the rib cage upwards and outwards. This further expands the chest cavity. [Reference: When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside. 02-Feb-2023]
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Pressure Decrease: This expansion of the chest cavity decreases the air pressure inside the lungs, creating a pressure gradient. Air, naturally moving from high to low pressure, rushes into the lungs through the nose and mouth. [Reference: Air moves in and out of the lungs in response to differences in pressure.]
Exhalation (Expiration)
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Diaphragm Relaxation: During exhalation, the diaphragm relaxes and resumes its dome shape, decreasing the volume of the chest cavity. [Reference: During inhalation process, the diaphragm contracts and moves down. The ribcage moves upwards… ]
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Intercostal Muscle Relaxation: The intercostal muscles also relax, allowing the rib cage to move downwards and inwards.
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Pressure Increase: The reduction in chest cavity volume increases the air pressure within the lungs. This higher pressure pushes the air out of the lungs, through the nose and mouth. [Reference: Air moves in and out of the lungs in response to differences in pressure.]
Control of Breathing
Breathing is not entirely involuntary; it's controlled by the respiratory center in the brainstem. This center monitors carbon dioxide levels in the blood. High carbon dioxide levels trigger increased breathing rate and depth. [Reference: Breathing is triggered by carbon dioxide. Our body needs to get rid of the carbon dioxide present in our body. Hence, carbon dioxide is the main trigger of… ] [Reference: Breathing is a complex process that relies heavily on the coordinated action of the muscles of respiration and the control center in the… ]
Summary
In short, breathing is a rhythmic process driven by the coordinated action of the diaphragm, intercostal muscles, and the respiratory control center in the brain, resulting in pressure changes that facilitate the exchange of gases between the lungs and the atmosphere.
