Question

With regard to the respiratory system and the process of respiration, answer the following questions:

(a) Name the two muscles that help in breathing.

(b) Briefly describe how the above mentioned muscles help in the inspiration of air.

(c) What is meant by :

1. Residual air
2. Dead air space. [6 marks]

Answer 1

(a)The two muscles that help in breathing are: intercostal muscles and abdominal muscles.
[2 marks]

(b) The pressure in the thoracic cavity decreases while the volume of the chest cavity increases as the ribs moves upwards and outwards, which happens due to the contraction of the diaphragm.
[2 marks]
(d)

1. Residual volume is the volume remained in the lungs even after a forceful expiration. Its volume is 1500 ml.
   [1 mark]
2. Dead air space is the tidal space remaining in the respiratory passages like bronchi or trachea, where the gas diffusion does not take place. Its volume is 150 ml.
   [1 mark]