Oxygen enters the blood in the
D. alveoli
the choices are
A. bronchi.
B. pharynx.
C. larynx.
D . alveoli
Oxygen enters the blood in the lungs through a process called respiration. During respiration, we breathe in oxygen-rich air, which travels down our respiratory system and enters the lungs. Let me explain the process in more detail:
1. Inhalation: When we inhale, the diaphragm contracts, and the rib muscles expand the chest cavity. This action increases the volume of the lungs, causing a decrease in air pressure within them. As a result, air from the atmosphere flows into the lungs through the nose or mouth.
2. Gas Exchange: Inside the lungs, there are millions of tiny sacs called alveoli. These sacs are surrounded by an extensive network of capillaries. As the inhaled air enters the alveoli, it comes into contact with the capillaries.
3. Diffusion: Oxygen in the alveoli has a higher concentration compared to the oxygen in the capillaries. This concentration gradient allows oxygen molecules to diffuse from the alveoli into the capillaries.
4. Oxygen Binding: Once oxygen enters the capillaries, it binds to a protein in red blood cells called hemoglobin. Hemoglobin has a high affinity for oxygen, allowing it to bind to oxygen molecules easily.
5. Oxygen Transport: Once bound to hemoglobin, oxygen is carried by the red blood cells throughout the body. The circulatory system ensures that oxygen-rich blood is pumped to various tissues and organs, delivering the oxygen they need to function.
It's important to note that carbon dioxide, a waste product of cellular respiration, also diffuses into the alveoli from the capillaries. During exhalation, carbon dioxide is released from the body. This gas exchange of oxygen and carbon dioxide in the lungs enables the oxygen to enter the bloodstream and carbon dioxide to be eliminated from the body.