How does the respiratory system deliver oxygen to different parts of body?
1. Inhalation:
- The process of breathing begins with inhalation, where air is drawn into the body through the nose or mouth.
- During inhalation, the diaphragm contracts, moving down, and the intercostal muscles between the ribs contract, expanding the chest cavity.
- This expansion lowers the air pressure in the lungs, causing air to flow in.
2. Gas Exchange in the Lungs:
- Once air enters the lungs, it travels through the airways, including the trachea, bronchi, and bronchioles, until it reaches the tiny air sacs called alveoli.
- Inside the alveoli, a process called gas exchange occurs. Oxygen from the inhaled air passes through the walls of the alveoli and into the bloodstream.
- At the same time, carbon dioxide, a waste product of cellular respiration, diffuses out of the blood vessels surrounding the alveoli and into the air sacs.
3. Blood Circulation:
- The oxygenated blood from the lungs is transported by the heart through the blood vessels.
- The heart pumps the oxygen-rich blood from the left ventricle through the aorta, the largest artery in the body.
- From the aorta, the oxygenated blood is distributed to smaller arteries, which branch out into even tinier capillaries throughout the body.
4. Capillary Exchange:
- In the capillaries, the oxygen from the blood plasma diffuses through the thin capillary walls and into the surrounding tissues and cells.
- The cells utilize oxygen for cellular respiration, which produces energy for their various functions.
- Simultaneously, carbon dioxide, produced as a waste product of cellular respiration, diffuses from the cells into the capillaries.
5. Return to the Heart:
- The deoxygenated blood, now containing carbon dioxide, flows back to the heart through small veins, joining larger veins, ultimately reaching the right atrium.
- From the right atrium, the blood is pumped to the right ventricle, which then contracts, pushing the deoxygenated blood into the pulmonary arteries.
6. Exhalation:
- The pulmonary arteries carry the deoxygenated blood back to the lungs.
- In the lungs, the carbon dioxide diffuses out of the blood vessels into the alveoli, while a fresh supply of oxygen moves into the bloodstream.
- The diaphragm and intercostal muscles relax, allowing the chest cavity to recoil and the lungs to contract, pushing the carbon dioxide-rich air out of the body through the nose or mouth during exhalation.
This continuous cycle of inhalation, gas exchange, blood circulation, and exhalation ensures a constant supply of oxygen to different parts of the body and the removal of carbon dioxide, facilitating proper cellular function and sustaining life.