Answer the following:

Explain respiration in human beings.

● Taking in and giving out air is called breathing.

● Breathing is done with the help of the respiratory system.

● The respiratory system consists of nose, pharynx, larynx, trachea, bronchi, and lungs.

● Lungs include bronchioles and alveoli.

● The process of breathing:

● Air enters the nasal cavity through the nostrils.

● Dust particles present in the air are prevented from reaching the lungs.

● Air passes to the pharynx, and then into the trachea with the help of epiglottis.

● The trachea is supported by ‘C’ cartilaginous rings which prevent the trachea from collapsing.

● The trachea is divided into two branches called bronchi.

● One bronchus enters the left lung and the other enters the right lung.

● These bronchi are further branched into bronchioles.

● Air sacs are present at the terminals of bronchioles. These are called alveoli.

● Gaseous exchange occurs in the alveoli, gives out carbon dioxide and collects oxygen.

● Oxygenated blood distributes oxygen to the cells.

● Oxygen is used to oxidize food to release energy in the process of cellular Respiration.

● Carbon dioxide that is formed as a by-product during respiration is carried by the blood to the alveoli.

● Carbon dioxide is exhaled out through nostrils.