Respiratory System

• Oxygen is the part of the air that we breathe
• The air you breathe is made up of Oxygen (21%), Nitrogen (78.1%), Carbon dioxide (0.03%) and other gases (0.87%)
• Breathing is a mechanical process. It is a process of pumping air into and out of the lungs. Breathing is done by a group of organs that make up the respiratory system.
• The function of the respiratory system is to exchange oxygen and carbon dioxide between the air and the cells
• The function of the nose is to filter and warm the entering air with the help of the cilia (hairs inside it).
• The pharynx is commonly called the throat. It connects the nose with the windpipe.
• The trachea is a tube that enters the chest and allows air to flow from the mouth into the bronchi and from there into the lungs.
• When dust particles and germs in the air enter the trachea during inhalation, the mucus lining the trachea traps these particles and the cilia work together to move them out of the body. When you sneeze or cough you expel the mucus and foreign particles from your body.
• The trachea splits into two air tubes, called bronchi that connect to each of the lung
• As the bronchial tubes pass through the lungs, they divide into smaller air passages called bronchioles
• The bronchioles end in tiny balloon-like air sacs called alveoli. Your body has over 300 million alveoli. The alveoli are surrounded by a mesh of tiny blood vessels called capillaries.
• The main organs of the respiratory system are the lungs
• The lungs are two up- side-down, cone-shaped organs inside the chest
• The lungs are really two bags full of thousands of alveoli. The tiny alveoli or air bags in the lung are surrounded by small capillaries where gaseous exchange takes place.
• The diaphragm is a large muscle that lies at the bottom of the chest cavity. This dome shaped muscle below the lungs enables you to breathe.
• When it contracts, it moves downwards, and your lungs fill with air. When it relaxes again it moves upwards and forces the air out of your lungs. This is the main muscle used for breathing
• The Process of Respiration

  1. Breathe in/inhale

  2. Diaphragm contracts

  3. Diaphragm moves down

  4. Chest cavity size increases

  5. Ribs move up

  6. Chest cavity size increases

  7. More space in lungs

  8. Lower air pressure in lungs

  9. Air pushes in from outside

  10. Breathe out/exhale

  11. Diaphragm relaxes

  12. Diaphragm and ribs return to original place

  13. Chest cavity returns to original size

  14. Less space in lungs

  15. Higher air pressure in lungs

  16. Air pushes out to outside
• RESPIRATION is a chemical process in which oxygen and carbon dioxide are exchanged between the outside air and the cells.
• Respiration takes place in two stages: 1. External Respiration: is the

  exchange of gases between the

  air and the blood.

  2. Internal Respiration: is the

  exchange of gases between the

  blood and the cells.

  External respiration takes place

  at the alveoli.
• The surfaces of the alveoli are covered with a network of tiny blood vessels that are called Capillaries
• The walls of the alveoli are one cell thick. The walls of the capillaries are also one cell thick. By diffusion, oxygen passes from the alveoli in the lungs into the capillaries. Across two rows of cells. At the same time, carbon dioxide passes from the capillaries to the alveoli across the same two rows of cells.