They are called alveoli
In mammals, air enters the lungs through tubes called bronchi, which branch into smaller tubules called bronchioles. These bronchioles extend out to tiny air sacs called alveoli, where gas exchange occurs.
It enters through the capillaries of the lungs.
the air enters the bronchioles, and into the aveoli, which are small, one cell-thick sacks of air. These sacks are surrounded by tiny capillaries, which is how your blood retrieves its oxygen. From here, the oxygenated blood is carried back to the heart through the pulmonary vein and pumped into your body.
As oxygen enters the body it will travel down the trachea (throat), through the bronchioles (tubes leading to the lungs), and into the lungs. In the lungs there are very tiny grape-like-sacs called alveoli. The membrane on these sacks is very thin, and they are surrounded by many tiny capillaries (blood vessels) whose membrane is also very thin. It is here where oxygen from the alveoli enters the capillaries, and carbon dioxide (waste product) from the capillaries enters the alveoli. The oxygen is now carried through the blood to the heart where it is pumped throughout the body, and the carbon dioxide, now in the alveoli, is expelled as the person exhales. In a situation of altitude it is this process that is hindered. Because of the lower pressure of oxygen the oxygen does not enter the capillaries as easily and the body is deprived of oxygen.
Glomerulus
Oxygen enters the body through the respiratory system. It is inhaled through the nose or mouth, travels down the trachea, enters the lungs, and then diffuses into the bloodstream through tiny blood vessels called capillaries in the lungs.
Capillaries. The diffusion of nutrients, oxygen, carbon dioxide and wastes take place in the capillaries. If you want to be more specific, it would be the venous ends of the capillaries where carbon dioxide enters the blood.
After air passes through the trachea, it enters the bronchial tubes that branch out into smaller airways called bronchioles. In the bronchioles, the air is distributed to the alveoli, small air sacs in the lungs where oxygen is absorbed into the bloodstream and carbon dioxide is released for exhalation.
The oxygenated blood first enters the capillaries, then they carry the blood through other veins to the rest of the body.
You breathe the oxygen into your lungs. The oxygen then dissolves into the water lining which is called the alveoli. Finally, the oxygen will cling to the red blood cells as they pass through the alveolar capillaries and now the oxygen is in the blood.
tertiary bronchioles
Yes, capillaries form a network around the alveoli. It is through the alveolar walls and into the capillaries that oxygen enters the blood stream. Carbon dioxide leaves the blood by the reverse route.