"Respiratory system of Human being"

Respiratory system:

• This system includes the nose, mouth, throat, voice box, windpipe, and lungs. Air enters the respiratory system through the nose or the mouth. If it goes into the nostrils (also called the nares).
•  Tiny hairs are called cilia.
•  The two loops of the airway meet at the pharynx, or throat, at the back of the nose and mouth. 
• The pharynx is part of the digestive system, and the respiratory system because it carries both food and air. At the bottom of the pharynx, this pathway divides in two, one for food — the esophagus, which leads to the stomach — and the other for air. 
• The epiglottis, a small flap of tissue, covers the air-only passage when we swallow, keeping food and liquid going into the lungs. 
• The larynx, or voice box, is the top part of the air-only pipe and it makes sound in voice. 
• The trachea, or windpipe, is the continuation of the airway below the larynx. The walls of the trachea are strengthened by stiff rings of cartilage to keep it. At its bottom end, the trachea divides into left and right air tubes, called bronchi, which connect to the lungs.
•  Within the lungs, the bronchi branch into smaller bronchi and even smaller tubes, bronchioles. Bronchioles end up in tiny air sacs, called alveoli, where the exchange of oxygen and carbon dioxide actually takes place. 
• The lungs also contain elastic tissues that allow them to inflate and deflate without losing shape.
•  They're covered by a thin lining, the pleura. The chest cavity, or thorax, is the airtight box that houses the bronchial tree, lungs, and other structures.
•  The top and sides of the thorax are formed by the ribs and attached muscles, and the bottom is formed by a large muscle, called the diaphragm in human being.