External respiration takes place in the
External respiration takes place in the lungs.
External respiration takes place in the respiratory system, specifically in the lungs. To understand how external respiration occurs, let's break it down into three main steps:
1. Breathing: The process starts with inhalation, where you draw air into your lungs through the nose or mouth. The air travels down the trachea and further into smaller branches called bronchi, which eventually lead to tiny air sacs called alveoli in the lungs.
2. Gas exchange: Once the air reaches the alveoli, oxygen molecules in the air pass through the thin walls of the alveoli and enter the bloodstream. At the same time, carbon dioxide molecules, which have accumulated in the bloodstream from cellular respiration, move from the blood into the alveoli to be exhaled.
3. Transport: The oxygen molecules in the bloodstream bind to red blood cells, which then carry it to various parts of the body. Conversely, carbon dioxide, which has been collected from the body's cells, is transported by the red blood cells back to the lungs to be exhaled.
In summary, external respiration occurs in the lungs and involves the process of breathing in air, gas exchange between the alveoli and the bloodstream, and the transportation of gases to and from the body's cells.