Problem 5

Question

The structures at which one third of \(\mathrm{O}_{2}\) in the atmosphere moves into the blood of humans are: a. alveoli. b. bronchi. c. bronchioles. d. tracheae. e. pharynges.

Step-by-Step Solution

Verified
Answer
a. alveoli.
1Step 1: Identify the purpose of each structure
The first step is to understand the role of each structure. Alveoli are tiny air sacs in the lungs where exchange of oxygen and carbon dioxide takes place. Bronchi are the main passageway into the lungs. Bronchioles, are small branches of bronchi that lead to alveoli. Trachea is the windpipe that starts from the larynx to the bronchi. Pharynges are part of the throat behind the nose and mouth that help in breathing and swallowing.
2Step 2: Select the right structure
Out of all these structures, the key function of allowing oxygen to pass from the lungs to the bloodstream is performed by the alveoli. In the alveoli, oxygen from the air is transferred into the blood and carbon dioxide, a waste product of metabolism, is transferred from the blood to the air. The other structures are important parts of the respiratory system, but the actual gas exchange doesn’t take place there.