How does oxygen get from the air to working muscle?

The process of how oxygen gets from the air to working muscle involves several physiological mechanisms. Here's how oxygen is transported:

1. Inhalation: Oxygen enters the body through the respiratory system during inhalation. When we breathe in, the diaphragm contracts, and the intercostal muscles elevate the rib cage, causing the lungs to expand. This expansion creates a negative pressure in the pleural space, drawing air into the lungs.

2. Diffusion in the Lungs: The inhaled air reaches the alveoli, which are tiny air sacs in the lungs. Oxygen molecules diffuse from the alveoli into the capillaries surrounding them. This diffusion occurs because there is a higher concentration of oxygen in the alveoli compared to the capillaries.

3. Oxygen transport in Blood: Once oxygen diffuses into the capillaries, it binds to hemoglobin, a protein found in red blood cells. Each hemoglobin molecule can carry four oxygen molecules. The oxygen-rich blood is then pumped by the heart through the pulmonary veins to the left atrium.

4. Systemic Circulation: From the left atrium, the oxygenated blood flows into the left ventricle, which pumps it into the aorta, the largest artery in the body. The aorta branches into smaller arteries, which deliver oxygenated blood to various tissues and organs, including skeletal muscles.

5. Diffusion in Muscles: In the muscle capillaries, oxygen diffuses from the blood plasma into the interstitial fluid surrounding the muscle cells. Then, it further diffuses through the muscle cell membrane and into the muscle fiber, where it undergoes cellular respiration to generate energy.

Overall, the process involves inhalation, diffusion across the alveoli, transport in the bloodstream by hemoglobin, and subsequent diffusion into muscle cells, facilitating the delivery of oxygen to muscles for energy production.