how respiration takes place in our body

The human respiratory system supplies our body with O2 and also helps in removing CO2, which is a waste product formed during cellular respiration. The intake of O2 and exit of CO2 involves two processes:

1) Inhalation: It involves bringing in air from outside the body into the lungs. When we breathe in, the size of our chest increases.

This happens because when air enters, the lungs expand and the ribs move outwards. Simultaneously, the diaphragm contracts and becomes flat. Thus, the size of our chest increases.

2) Exhalation: It involves removal of CO2 from the body. When we breathe out, the size of our chest decreases. This happens because when air moves out of our lungs, the lungs contract, the ribs move back, and the diaphragm curves upwards into the chest decreasing the size of the chest.

Organs involved in respiration:

The organs of the respiratory system extend from the nose to lungs. They include the nose, pharynx, trachea, bronchi, and bronchioles.

1) Nostrils: The air from outside first enters the nostrils, which is divided into the left and the right nostril. These nostrils lead to open spaces in the nose called the nasal passage. This passage contains hair and mucus, which perform the functions of filtering, moistening, and warming the air entering the nasal passage.

2) Pharynx: Air travels from the nasal passage to the pharynx, which is commonly known as throat. The pharynx is lined with a protective mucus membrane and cilia, which removes the impurities entering with air.

3) Larynx: The air from the pharynx enters the larynx or voice box. It contains two true vocal cords, which are made up of cartilage and fibres. When air passes through this area, the vocal cords vibrate and this produces different sounds. Human beings can control this vibration. Thus, they can make various sounds and are capable of speech.

4) Trachea: From the larynx, the inhaled air moves into the wind pipe or trachea.

The trachea is a long narrow tube, which is lined with ciliated mucus membrane. The trachea branches into two tubes, the left and right bronchi. The cilia move the mucus containing dust particles back to the pharynx, where it is swallowed.

5) Bronchi and bronchioles: The air from the trachea moves into the bronchi, which are formed because of the division of the trachea. Each bronchus enters one of the lungs. Inside the lungs, the bronchi further divide into bronchioles. The air moves through these bronchioles.

6) Alveoli: The bronchiole divides many times in the lungs to create smaller branches. These branches ultimately terminate into tiny air-sacs known as alveoli. These cells are surrounded by many blood capillaries.

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