Respiratory System
Cellular respiration is a series of reactions that breaks down glucose, a simple sugar, releasing chemical energy for your body to use. In order to use this sugar or “burn these calories,” your body needs oxygen (like a fire needs oxygen for combustion). Cellular respiration uses oxygen and releases carbon dioxide and water as waste products. Blood is the delivery system that carries oxygen to all your cells from the lungs and returns to the lungs with carbon dioxide waste.
Respiratory Tract:
- You breathe air in through your mouth and nose.
- From there, the air moves into your pharynx, which is a passageway in your throat that leads to both your stomach and lungs. The epiglottis is a flap (the little punching back in the back of your throat) that prevents food from going into your airway, but when you breathe, the epiglottis remains open.
- From there, air moves into the larynx, a part of the air passage where your vocal cords are located.
- The air then moves into the trachea, which is lined with cartilage to keep it firm and ensure it doesn’t collapse. The trachea also has tiny hairlike structures (called cilia) and mucus to trap bacteria, dust, or any particles that shouldn’t be going into your lungs.
- Next, the air moves into tubes leading to your lungs called bronchi. The word ‘bronchi’ looks like of like ‘branch’, and that is exactly what happens to the bronchi: They branch into smaller tubes called bronchioles.
- Bronchioles connect directly to alveoli, millions of tiny air sacs. Oxygen from the air in the alveoli moves into the blood in the capillaries to be distributed throughout your body so respiration can happen in all of your cells. At the same time, carbon dioxide waste in the blood moves into air in the alveoli to be exhaled.
Breathing
Breathing is the mechanical process of taking in air. You breathe automatically--you don’t have to think about breathing. If you need more oxygen, you breathe faster (which is why you get out of breath when you exercise--your body needs more oxygen to burn more calories for energy).
When you squeeze a sponge, all of the air and water rushes out, and when you let go, the sponge expands and the air rushes back in. Breathing works the same way. Air gets pulled into your chest when your chest expands, and pushed out when it contracts. A muscle under your rib cage called the diaphragm controls this expanding and contracting motion.