Events that occur during internal respiration.

1. Oxygen diffuses from the alveoli in the lungs into the bloodstream.
2. Oxygen is transported by red blood cells to tissues and cells throughout the body.
3. Carbon dioxide produced by cells is transported by red blood cells back to the lungs.
4. Carbon dioxide diffuses from the bloodstream into the alveoli in the lungs.
5. Oxygen is released from red blood cells and diffuses into cells for cellular respiration.
6. Carbon dioxide is produced as a byproduct of cellular respiration and is carried back to the lungs for exhalation.

Internal Respiration: The exchange of oxygen and carbon dioxide between body cells and blood capillaries.

Events:

1. In Capillaries:
- Oxygen from blood diffuses into interstitial fluid and then into cells.
- Carbon dioxide from cells diffuses into interstitial fluid and then into blood.

2. In Cells:
- Oxygen enters mitochondria for use in cellular respiration.
- Carbon dioxide is produced as a waste product of cellular respiration.

3. Back in Capillaries:
- Carbon dioxide diffuses back into blood.
- Oxygen-depleted blood flows to lungs for exchange with fresh air.

Additional Factors Affecting Diffusion:

- Partial pressures: Higher partial pressure of oxygen in capillaries promotes diffusion into cells, while higher partial pressure of carbon dioxide in cells promotes diffusion into blood.
- Concentration gradients: Differences in oxygen and carbon dioxide concentrations between blood and cells drive diffusion.
- Membrane permeability: Oxygen and carbon dioxide must pass through capillary and cell membranes, which have varying permeability.
- Blood flow: Adequate blood flow is necessary to maintain oxygen and carbon dioxide exchange.