The order of flow of oxygen within the human body may be described simply. Oxygen first is inhaled through the nasal cavity and then passes through the trachea, through the bronchi and into the lungs. In the lungs, the oxygen is passed into the blood stream through the alveoli and then is carried to the heart. The heart pumps this oxygenated blood throughout the body, primarily to organs and muscle cells, where it is consumed in respiration and is converted to carbon dioxide and excreted.
Answer:
they are smaller then cells
Explanation:
they are composed of many atoms
Of lower concentration and higher concentration
Well matter is basically any substance that has mass and takes up space. Example, you have a ball, or a table, or anything really. That is mass. But anything that doesn't take up space or has mass isn't matter. So, anything that doesn't have a mass or take up space is not matter. Hope this helped you understand. :D