CBSE Class 10 - Science - Life Processes - Pathway of Air (#cbseNotes)

 Life Processes - Pathway of Air
(Breathing Process)

CBSE Class 10 - Science - Biology

Breathing process involves a the pathway of air from nostril to alveolus. It is a physical process. The pathway is described as follows:

Nostrils:         ⇅	Air usually enters the body through the nostrils.
Nasal cavity: ⇅	Air is filtered. The moist surface of the lining of the nasal cavity, and the hairs growing from its sides, remove some of the tiny particles of dirt in the air. In addition, as the inhaled air passes through the nasal cavity, its temperature is brought close to that of the body, and it takes up water vapour so that it becomes more moist than before.
Pharynx: ⇅	Warming and moistening goes on in this common passage of digestive and respiratory system. Epiglottis, a flap like muscular valve controls movement of food and air towards their respective passages.
Larynx: ⇅	This stiff box contains our vocal cords. When air passes out of the lungs and over the vocal cords, it causes them to vibrate. This produces sounds on the basis of our speech, song etc.
Trachea: ⇅	Wind pipe channeling air to lungs. Touch your neck to feel the tube like structure.
Bronchi: ⇅	At its lower end the trachea or the wind pipe divides into two bronchi-one leading to each lung.
Bronchioles: ⇅	Each bronchi is further divided into smaller and smaller branches called bronchioles.
Alveolus: ⇅	These finally terminate in clusters of air sacs called alveoli in the lungs which are very small and numerous. Gaseous exchange takes place here as blood capillaries take up oxygen and expel carbon dioxide.
Blood: ⇅	Carries oxygen, collects CO 2 to each and every cell of the body.

The whole passage from nostrils to alveolus is moist and warm.