The human heart pumps blood to all parts of the body, but it refers to the lungs to displace CO2, bringing in new oxygen stores that can regenerate the blood supply.
The air passing through the body can be better described in this way ...
oAir enters the nostrils
opuses through the nasopharynx,
oral pharynx
through publicity
in trachea
as well as the right and left bronchi, which
obronchioles, each of which ends in a cluster
oalveoli [1]
The inner part of the lungs contains 300 million alveoli, which are the "Final branches of the respiratory tree and act as primary gas exchange units in the lungs." The gas barrier between the alveolar space and the pulmonary capillaries is extremely thin, which allows you to quickly exchange gas. To reach the blood, oxygen must diffuse through the alveolar epithelium, thin interstitial space and capillary endothelium; CO2 follows a return course to reach the alveoli. " [2]
The estimated surface area of the alveoli is approximately equivalent to an area 80 times the size of our skin covering. And each of these alveoli works to provide the proper function of the ratio of oxygen to CO2 in our systems.
In essence, whenever you breathe, you pass oxygen through the walls of the lungs into the bloodstream, while CO2 gases pass through the lining of the lungs to escape through your nose or mouth.
Most adults breathe between 4-12 times per minute. This allows the body to continue to transmit oxygen to every part of your body - even while you sleep.
A variety of muscles (abdominal, intercostal) help the lungs draw in air and push away CO2 gases.
Several independent systems must work together to ensure that the lungs accept the necessary oxygen. The lungs help the heart to recharge the blood system with oxygen. Blood fills the body with nutrients and oxygen, which are necessary for returning to the lungs to remove gases emitted by CO2.
You lungs will adjust to higher elevations to draw in more air to get similar oxygen requirements. This is often achieved through dilated bronchioles. This essentially allows your body to breathe faster with fewer problems than in an environment rich in oxygen.
Is it possible that several of the systems needed to effectively supply the body with oxygen are a product of advanced design or a series of random, independent improvements over millions of years?
Perhaps the lungs look like they are designed.
[1] http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Pulmonary.html
[2] http://oac.med.jhmi.edu/res_phys/Encyclopedia/Alveoli/Alveoli.HTML
