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Ventilation, Diffusion and Perfusion


Published: 20 June 2019

Cover image for article: Ventilation, Diffusion and Perfusion

Ausmed Explains... Ventilation, Diffusion and Perfusion

The respiratory process consists of three components. Ventilation, diffusion and perfusion.

Ventilation consists of two parts:

  • Inspiration, which is the expansion of the chest with a negative intrapulmonary pressure when air flows into the thorax; and
  • Expiration, when the intrapulmonary pressure is higher than the atmosphere, air will flow out of the lungs.

Diffusion is the process whereby gases move from an area of high pressure to low pressure. This includes during:

  • Internal respiration - this is the movement in the internal tissues between cells and capillaries, and
  • External respiration - when gas is exchanged between the alveoli and lung capillaries.

Perfusion refers to the blood flow to tissues and organs. Alveoli are perfused by capillaries so the diffusion of oxygen and carbon dioxide can take place.

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12 Total Rating(s)

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Hayley Brosnan
11 Jan 2020


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Vanessa Milne
24 Oct 2019

Complex topic reasonably well explained.

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Helena Mitipelo
08 Jul 2019

Very informative I understood what was being said.

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Lynda O'Maley
24 Jun 2019

A quick snap shot of pulmonary function.

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Yvonne Martin
22 Jun 2019

Explanation of ventilation, Diffusion and Perfusion