capillaries
Capillaries are the blood vessels that surround the alveoli, or air sacs, in your lungs. These capillaries are the site of gas exchange.
The air sacs send oxygen to the cells.
The lungs are the primary organs that fill blood with oxygen. Oxygen from the air is inhaled into the lungs, where it moves into the bloodstream through tiny blood vessels called capillaries surrounding the lungs' air sacs.
kidney glomeruli, air sacs of the lungs, lining of the heart, blood vessels, and lymphatic vessels, lining of the ventral cavity (serosae).
air sacs are in the lungs and when you breathe in blood carries it to the lungs.
lungs
The tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged are called alveoli. They are surrounded by blood vessels through which gas exchange takes place during the process of respiration.
A lot of the lung tissue can be damaged by smoking, but you seem to be asking about the alveoli (singular = alveolus). These are small sacs surrounded by blood vessels that are located at the end of the various branches of the air passageways inside the lungs.
Capillaries . The smallest of the blood vessels: capillaries.
Because the air sacs carry oxygen to the blood!
They are the alveoli.
The lungs take in oxygen, this oxygen travels down to the alveoli (thin, permeable sacs), which are covered in blood vessels, and the oxygen travels into the blood due to a pressure difference and CO2 goes from the blood to the lungs to be exhaled. The body needs that oxygen for almost every system in the body.