Describe the path of oxygen from when it enters your mouth to the blood.
When oxygen enters your mouth, it first passes through the nasal cavity. The nasal cavity is lined with tiny hairs called cilia, which help filter out dust and other particles, as well as warm and humidify the air. From the nasal cavity, the oxygen travels down the pharynx, a muscular tube at the back of the throat.
From there, the oxygen moves into the larynx, commonly known as the voice box, which helps produce sound. The larynx connects to the trachea, also known as the windpipe. The trachea is a wide tube lined with cilia and mucus-producing cells, which continue to filter and moisten the air.
The trachea divides into two bronchi, one leading to each lung. Within the lungs, the bronchi branch out into smaller tubes known as bronchioles, which further divide into tiny air sacs called alveoli. The alveoli are the gateway to the bloodstream.
Here, the oxygen diffuses across the thin walls of the alveoli and enters into tiny blood vessels called capillaries. The walls of the capillaries are incredibly thin, allowing for efficient exchange of gases. Oxygen molecules bind to the red blood cells inside the capillaries, forming oxyhemoglobin.
The oxygen-rich blood then travels through the pulmonary veins to the left side of the heart. The heart pumps oxygenated blood into the aorta, the largest artery in the body. From the aorta, the oxygenated blood flows to all parts of the body through a network of smaller arteries and arterioles, eventually reaching the tissues and organs.
At the cellular level, oxygen diffuses from the capillaries into the tissue cells, providing essential oxygen for metabolic processes. After oxygen is utilized, carbon dioxide, a waste product of cellular respiration, is produced. The carbon dioxide will travel back to the lungs, following the reverse pathway, to be exhaled out of the body.