What is the primary structure for gas exchange in the respiratory system, how is it deisgnedf or the job?

Alveoli.

http://oac.med.jhmi.edu/res_phys/Encyclopedia/Alveoli/Alveoli.HTML
http://en.wikipedia.org/wiki/Alveoli
http://lungdiseases.about.com/od/glossaryofterms/g/alveoli.htm
http://science.nhmccd.edu/biol/respiratory/alveoli.htm
http://hyperphysics.phy-astr.gsu.edu/hbase/ptens2.html

I hope this helps. Thanks for asking.

The primary structure for gas exchange in the respiratory system is the alveoli. The alveoli are millions of tiny, sac-like structures found at the end of the respiratory bronchioles in the lungs. They are designed specifically for the efficient exchange of gases, such as oxygen and carbon dioxide, between the air and blood.

To understand how alveoli are designed for their job, let me explain the process of gas exchange in the respiratory system:

1. Breathing: When you inhale, air containing oxygen enters your respiratory system through the nose or mouth. It travels through the trachea and branches off into smaller airways called bronchi, bronchioles, and finally reaches the alveoli.

2. Structure: Alveoli are surrounded by a network of capillaries, which are tiny blood vessels. This close proximity allows for direct contact between the air in the alveoli and the blood in the capillaries.

3. Thin walls: The walls of the alveoli are extremely thin, consisting of a single layer of flattened cells called epithelial cells. This thinness facilitates the diffusion of gases across the alveolar membrane, making it easier for oxygen to move from the air into the bloodstream and for carbon dioxide to move in the opposite direction.

4. Moist surface: The inner surface of the alveoli is lined with a thin layer of moisture. This moisture helps to dissolve oxygen from the air, making it more accessible for diffusion into the bloodstream.

5. Large surface area: Alveoli are numerous and clustered together, providing a large surface area for gas exchange. This allows for a greater amount of oxygen to be absorbed into the blood and a larger volume of carbon dioxide to be expelled from the body.

In summary, the alveoli are designed with thin walls, moist surfaces, and a large surface area to optimize the exchange of gases between the air and blood, thereby ensuring efficient respiration.