Unit-2 chapter-1 Pg:- 42,43,44,45.
Alveoli are a part of the lungs that help in gas exchange.
They are small air sacks located at the end of the lungs.
Alveoli are covered by large amounts of blood capillaries, which means a good blood supply.
The exterior of the alveoli is made up of only one layer of cells, and so is the blood vessel, this helps gases diffuse through the cells.
Because the blood is in motion there is a low concentration of gas in the blood vessel, this difference helps gas exchange.
There are two ways oxygen enters tissues, one through plasma, and another through hemoglobin.
There are three ways carbon dioxide enters the blood, one again through plasma, another by reacting with water to form bicarbonate and hydrogen ions. Still, the last way is similar to the second way, the carbon dioxide enters the red blood cell where an enzyme called carbonic anhydrase is found, what it does is that it catalyzes the carbon dioxide and water reaction, which is much faster than without it.