Gas exchange takes place inside the alveoil of your lungs explain how the presence of alveoli results in an efficient surface for gas exchange?
The alveoli are the sites of gas exchanges. This means that the gases oxygen and carbon dioxide are exchanged (or swapped). Oxygen is breathed in from the air and enters the lungs and into the blood. It is used in respiration which is a chemical process that produces energy as well as waste products carbon dioxide and water. Carbon dioxide needs to be removed from the body. Build up of carbon dioxide is dangerous as it can affect blood pH. Carbon dioxide is removed by transporting it in the blood to the lungs where it can be breathed out. The movement of the gases are in the following: Oxygen : air -> lungs -> alveoli -> blood -> cells Carbon dioxide: cells -> blood -> alveoli -> lungs -> air Note that alveoli are structures inside the lungs. Inhalation and exhalation allow oxygen and carbon dioxide to enter and leave the body. The two gases oxygen and carbon dioxide move according to diffusion. Diffusion is the movement of particles from an area of high concentration to an area of low concentration. Another definition is the movement of particles down their concentration gradients. A concentration gradient is the difference is concentration between two point. The bigger the difference, the steeper the concentration gradient, the faster the diffusion. The alveoli are sac like structures and appear in clusters at the end of bronchioles. They have a number of adaptions that make them good at gas exchange which are the following. 1. Alveoli have a large surface area. There are lots of them so lots of sites of exchange. 2. They have a good blood supply. Each alveoli is surrounded by capillaries. Capillaries carry the oxygen away. This means there is a much higher concentration of oxygen inside the alveoli and low concentration in the capillary maintaining a steep concentration gradient. The opposite applies to carbon dioxide. There is a high concentration of carbon dioxide in the blood and low concentration in the alveoli so the carbon dioxide diffuse from the blood into the alveoli where it can then be removed through exhalation. The blood supply allows a steep concentration gradient to be maintained. 3. The alveoli have walls that are one cell thick. This means that there is a short diffusion distance. The gases do not have to move very far to be exchanged. In addition capillary wall is also one cell thick. 4. Alveoli are moist. This allows oxygen to easily dissolve and diffuse. I hope this answers your question.
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