Recruitment

			RECRUITMENT

Definition :

	Recruitment in the respiratory system is the opening of preveously
closed (non conducting) capillaries to conduct blood flow during
increasing demands of gas exchange.


Description :
 	
	During an excercise or while under a stress, the demands of gas
exchange are enormously increased. Due to this fact, the pressure at the
pulmonary artery or vein increases which causes the resistance in the
pulmonary vascular to decrease. 
	Another thing that happens during this situation is that the
diffusing capacity in the lungs increases due to the increasing in both Dm
(diffusing capacity of the membrane) and Vc(Volume of blood in the
pulmonary capillary).
	Both of these factors is causing the opening of preveously closed
or non conducting capillaries. This non conducting capillaries are
particulary located in the upper parts of the lungs.

Relevant Equations :
        . 
	Vg = Dl.(P(2)-P(1))
        .
        Vg = Difussion flux of a gas across the membrane 	
      
        Dl = Diffusing capacity of a gas

        P1,2 = Change in pressure across the membrane

A sample problem:

Sample problems :

	Explain the chief mechanism for the fall in pulmonary vascular
resistance thast occurs as the pulmonary artery pressure is raised from
low levels.

Answers:

Recruitment, the opening of previously closed vessels, especially the capillaryes in the upper parts of the lung.

For more information see Chapter 4 (page 35-36) and Chapter 9 (page 135) in West .

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This page was written by Sandrawati Kosasih , a student in this course.

BME 403 Pages maintained by the T.A., Douglas Miles.