All the organisms are made up of cells. Group of cells make a tissue. Tissues collectively form organs and organs, working together form an organ system. Human and animal bodies are made up of many such organ systems which carry out different functions.
Respiration is the process in which oxygen is taken in and carbon dioxide is released from the body. Energy is also released which is utilized to carry out various living processes. The respiratory system consists of the following organs:-
Air enters the nose through two nostrils and reaches the nasal cavity. Here the air is warmed and filtered. The hair present in the nostrils stop the dust or germs from entering the human respiratory system.
The nasal cavity leads into an organ called pharynx. From the pharynx, the air passes into a chamber called larynx. The larynx produces sound and is also called the voice box. The opening of pharynx into larynx is guarded by a valve called epiglottis. This closes the opening while we swallow food and keeps it open during breathing.
The wind pipe is a delicate muscular tube situated in the front of oesophagus or the wind pipe. It is also called trachea. It is 12 cm in length and 2.5 cm in diameter. The wind pipe is divided into two parts called Bronchi as it enters the lungs.
When a person takes in a breath of air, the air travels through the nose or mouth, into the larynx, and then into the trachea, which is the main passageway into the lungs. The trachea divides into a right and left main bronchus. Each major bronchus then subdivides into smaller airway passages referred to as bronchi. As the airway passages make their way out to the lung tissue, the passages become smaller and are referred to as bronchioles.