The alveoli
Every cell in your body needs oxygen in order to live. The air we breathe contains oxygen and other gases. Once in the lungs, oxygen is moved into the bloodstream and carried through your body. At each cell in your body, oxygen is exchanged for a waste gas called carbon dioxide. Your bloodstream then carries this waste gas back to the lungs where it is removed from the blood stream and then exhaled. Your lungs and respiratory system automatically perform this vital process, called gas exchange. 1 ALVEOLI are the very small air sacs that are the destination of breathed-in air. 2  CAPILLARIES are blood vessels in the walls of the alveoli. 3  Blood passes through the capillaries, entering through your PULMONARY ARTERY and leaving via your PULMONARY VEIN. Oxygen from the air to cells. When we breathe in oxygen enters the small air sacs, called alveoli, in the lungs. Oxygen diffuses from there into the bloodstream. Oxygen is not carried in the plasma, but is carried by the red blood cells. These contain a red substance called haemoglobin, which joins onto oxygen and carries it around the body in the blood, then lets it go when necessary. The carbon dioxide produced during respiration diffuses out of the cells and into the blood plasma. The blood carries it to the lungs. It then diffuses across the walls of the alveoli and into the air, ready to be exhaled. 1  Page. 2  1. 3  2. 4  3. 5  4. 6  5. · just now. Report Abuse. The oxygen enters the bloodstream in the smallest part of the lungs called the alveoli. The alveoli are tiny structures on the lungs covered in capillaries, and this is where the gas exchange occurs. French Master · 6 years ago. Thumbs up. Best Answer: When you breathe in air, your lungs fill with oxygen. This happens because the air passes through the pharynx, then into your trachea (wind pipe), then goes through your left/right bronchus, into your bronchioles, and then FINALLY into your alveoli, which are small sacs. Through the very thin walls of the alveoli, oxygen from the air passes to the surrounding capillaries (blood vessels). A red blood cell protein called hemoglobin (HEE-muh-glow-bin) helps move oxygen from the air sacs to the blood. At the same time, carbon dioxide moves from the capillaries into the air sacs.  Other animals (including many vertebrates) oxygenate via other organs like the skin or gills. Oxygen dissolves in the liquid lining of the alveoli and then diffuses down a concentration gradient through the walls of the alveoli and capillaries into the plasma and into the red blood cells. Oxygen enters the tissues from the bloodstream because our bodies  need oxygen and food to release energy. The cells in the tissues  use the oxygen for various functions. Making the world better, one answer at a time. In most vertebrates oxygen enters the bloodstream via diffusion at the alveoli of the lungs. This diffusion (a passive thing) is accomplished because oxygen concentration in the lungs is much higher than that of the blood, even than that of oxygenated blood. Oxygen enters the tissues from the bloodstream because our bodies  need oxygen and food to release energy. The cells in the tissues  use the oxygen for various functions. In most vertebrates oxygen enters the bloodstream  via diffusion at the alveoli of the lungs. This diffusion (a  passive thing) is accomplished because oxygen concentration … in the  lungs is much higher than that of the blood, even than that of   oxygenated blood. Yes, in a sense the respiratory system removes oxygen from the air and replaces it with carbon dioxide. When the respiratory system takes in air, it reduces the concentration … of oxygen from 21% to 16%. The air is inhaled by the diaphragm into the trachea, which leads into the lungs via the bronchi. It enters the alveoli where the oxygen is taken to the red blood cells passing through the lungs. The red blood cells take the oxygen and combine it with the food from the intestines The exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.
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the part in the lungs where oxygen enters the bloodstream are