Figure 6 (below) shows tidal volume tracings (the peaks on the right) obtained f

Question

Figure 6 (below) shows tidal volume tracings (the peaks on the right) obtained from animals with various brain areas severed. The tracings illustrate the role each of the centres of the brain has in controlling breathing WARNING: This is a difficult exercise and you will have to think about what happens witlh each cut (in answering the questions below with reference to Fig 5 and the associated text). BOTH VAGUS BOTH VAGUS NERVES INTACTNERVES CUT FIRST CUT SC SUPERICR COLLICUL SECOND CUT INFER LICULI CENTRE 2 APNBUSTC CENTRE THIRD CUT et VRG FOURTH CUT 4. Figure 6: Tidal volume tracings with sectioning of the nervous system

Explanation / Answer

Cutting at the apneustic center lost reflex activity from pneumotaxic center of pons to medulla and its now controlled by medulla alone, The inspiratory and expiratory centers alone is present and it lost control over higher brain. So the inspiration and expiration is very irregular in both cycle and duration. The breathing is very shallow and deep at irregular intervals.

Vagus nerve contols over inflation of the lung by stimulating the receptors present in the muscles and carry from lungs to brain, cutting vagus nerve at this stage causes loss of this control and causes lung to overinflate.

Cutting the level of brain below the medulla completely stops breathing because, It lost all the contol of centers like pons, and medulla now there is no stimulas from brain to lung. so the respiration is completely stopped. Leading to death if there is no medical interventions.

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