Asked Nov 12, 2019

Explain the changes in the atmospheric and intrapulmonary air pressure, muscle contraction, lung and thoracic cavity during inspiration and expiration


Expert Answer

Step 1

Pulmonary ventilation is comprised of three pressures.

  1. Atmospheric pressure:

It is the pressure of the air present outside the body.

  1. Intra-alveolar or intrapulmonary pressure:

It is also known as intrapulmonary pressure. It is defined as the pressure present inside the lung’s alveoli. So, the pressure inside the lungs is the intrapulmonary pressure.

  1. Intrapleural pressure:

It is the pressure present inside the pleural cavity.



Step 2


The process of breathing is known as respiration. It has two different phases that is inhalation or inspiration and exhalation or expiration.


Step 3
  1. During the inspiration:

During the breathing cycle, the process of taking air inside the lungs is known as inspiration. It is the dynamic phase of ventilation as it occurs due to the muscle contraction.


The variations in the atmospheric pressure, intrapulmonary air pressure, muscle contraction, lung and thoracic cavity is given below:

During inspiration the contraction of diaphragm takes place and volume of the thoracic...

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