Mechanism of respiration

• Mechanism of respiration is the process by which the respiratory system facilitates the exchange of gases, primarily oxygen and carbon dioxide, between the body and the environment.
• Respiration of Mechanism can be divided into four main processes: ventilation, external respiration, internal respiration, and cellular respiration.

1. Ventilation (Breathing)

1. Inhalation:

   • Mechanism: The diaphragm contracts and moves downward, while the external intercostal muscles lift the ribcage, expanding the thoracic cavity.
   • Effect: This increases thoracic volume, creating negative pressure that pulls air into the lungs via the respiratory tract, reaching the alveoli.

2. Exhalation:

   • Mechanism: The diaphragm and external intercostal muscles relax, decreasing the thoracic cavity’s volume.
   • Effect: This creates positive pressure, pushing air out of the lungs.

2. External Respiration (Alveolar Gas Exchange)

• Location: Alveoli and pulmonary capillaries.
• Mechanism: Oxygen diffuses from the air in the alveoli into the blood, binding to hemoglobin in red blood cells.
• Simultaneously: Carbon dioxide diffuses from the blood into the alveoli to be exhaled.

3. Internal Respiration (Tissue Gas Exchange)

• Location: Systemic capillaries and body tissues.
• Mechanism: Oxygen-rich blood from the lungs is pumped through systemic circulation.
• Oxygen diffuses from the blood into tissues, while carbon dioxide produced by cells diffuses into the blood.
• The carbon dioxide-rich blood returns to the lungs via the right side of the heart.

4. Cellular Respiration (Energy Production)

• Location: Mitochondria in cells.
• Mechanism: Cells use oxygen to produce ATP (energy) through glycolysis, the citric acid cycle, and the electron transport chain.
• By-product: Carbon dioxide is produced and transported back to the lungs for elimination.

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