Work 3. Donders’s model

The purpose: to Study a role of negative pressure in a pleural cavity in a respiratory cycle.

Work course: Donders’s model represents a glass large bottle at which the bottom is cut off and is replaced by a rubber membrane which carries out a diaphragm role. The large bottle mouth is closed by a stopper through which glass tubes are spent. On one of them puts on canula with lungs of an animal. The second is informed with an environment.

To close a clip on a by-pass tube which is informed with an environment. To delay a rubber membrane and to observe increase in volume of lungs at respiration imitation.

To weaken a membrane or to press on it and to observe reduction of volume of lungs at exhalation imitation.

To receive model opened pneumothorax. For this purpose to delay a membrane downwards and, not releasing it to open a clip on a tube which is informed with an environment. Air fills a large bottle («a pleural cavity») and lungs are fallen down. Change of position of a membrane upwards and downwards does not lead to change of volume of lungs. We are convinced, that respiration in the conditions of opened pneumothorax is not possible.

To sketch Donders’s model.

References:

Basic:

1. GuytonJ.E.Hall.Medical Physiology. by W.B.Saunders company, 2003.-1064p.

2. William F.Ganong.Review of medical physiology. New York: Mc Graw-Hill, 2003.-912p.

Additional:

1. K Sembulingam /Prema Sembulingam/ Essentials of medical Physiology 2001.Jaypee.-480p.

2. G.I.Kositsky. Human physiology.1998.-445 p.

3. A.J.Vander. Human physiology: the mechanisms of body function/New York: Mc Graw-Hill Publishing Company,1990/-724 p.

4. R.Sh.Gull.Concise physiology: based on Guiton –Ganong-Chatterjee. Lahore: The Friends,2001.- 500 p.

5. S.Chaudhuri. Concise medical physiology/Calcutta: New Central Book agency cp.,2004.-624p.

6. C.L.Ghai/ a textbook of PRACTICAL PHYSIOLOGY/ Jaypee Brothers Medical Publishers/1993.-370 p.

 Control Questions

1. What muscles carry out the inspiration?

2. What muscles carry out the expiration?

3. How lungs participate in respiration?

4. What pressure in lungs on a inspiration and an expiration?

5. What motoneurones innervated intercostal muscles and a diaphragm?

6. For what purpose use Donders’s model?

7. What pressure in a pleural cavity on a inspiration and an expiration?

8. In what danger of getting wounds of a thorax?