respiratory system
Snemalna Knjiga Besedilo
- Students, one by one all of you are going to tell about how air reaches our lungs.
- In humans air is taken into the body through nostrils. The air passing through nostrils is filtered by fine hairs and mucus that line the passage.
- Then, the air passes through pharynx, larynx and trachea.
- Then it passes through the bronchi , bronchioles and then reaches the lungs.
- Within the lungs, the passage further divides into balloon like structure called alveoli .
- The alveoli provide a surface where the exchange of gases takes place.
- The blood brings CO2 from the rest of the body for release into the alveoli and the O2 in the alveoli is taken up by blood to be transported to all the cells in the body.
- During the breathing cycle, when air is taken in and let out, the lungs always contain a residual volume of air so that there is sufficient time for O2 to be absorbed and for the CO2 to be released.
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