Have a primitive digestive system
Answer:
Oxygen molecules in the tissues of the lung diffuse into the blood because the concentration of oxygen in the lung's tissues is more than the concentration of oxygen in the blood.
Explanation:
Diffusion is the movement of molecules from the region of higher concentration of the molecule to the region of lower concentration of the same molecule. Molecules in diffusion move <em>downward the concentration</em> <em>gradient</em> created by difference in concentration between two regions until an <em>equilibrium (equal concentration in the two regions)</em> is established.
Oxygen molecules diffuse into the tissues of the lung when an organism breathes-in during the process of breathing. The molecules in the now oxygen-rich tissues eventually start diffusing into the blood in the lung because the blood passing through the lung is always de-oxygenated or has lower oxygen concentration compared to the tissues of the lung.
Oxygenated blood moves into the heart, pumps round the body by the heart, gets depleted of oxygen and eventually find its way back to the lung where the process is repeated.
Diffusion of oxygen from the tissues of the lung into the blood will keep happening as long as oxygen keeps getting dissolved into the lung's tissues and an equilibrium is yet to be established between the tissues and the blood.
Explanation:
they are all related to CO2 in a way
