Path of an O2 molecule

11

O2 makes its way to mitochondria for cellular respiration for ATP

6

Then it dissolves in plasma or enters RBC and binds to hemoglobin

4

Then it goes into the smaller branching tubes: bronchi, bronchioli, and then the aveoli

2

Then it travels down the pharynx.

3

Then the trachea

9

There is another gas exchange at the muscle cell. RBC's partial pressure is bigger than the partial pressure of oxygen which causes it to to diffuse into the muscle.

10

Here it removes itself from the hemoglobin so it can pass through the capillary wall, into the interstitial fluid, and then diffuse through the membrane of the muscle cell.

8

O2 (bound to Hb) goes to the heart via pulmonary vein and leavs via aorta to the body cells (like muscle cells)

1

O2 enters the body via the sinuses or mouth.

7

O2 goes into the capillary because the pressure of the oxygen is greater in the aveolus and things move from high pressure to low pressure

5

In the aveoli, gas exchange occurs. O2 travels through the fluid in the aveolus and goes through the aveolus membrane, into the interstitial fluid and then into the capillary