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 with each cut (in answering the questions below with reference to Fig 5 and the associated text). BOTH VAGUS NERVES INTACT FIRST OUT SC NERVES CUT SUPER LICULI SECOND CUT INFER LLICULI NBUMOTAK CENTRE 2 APNBUSTC CENTRE THIRD OUT 3 DRG VRG FOURTH CUT SPINAL CORD Figure 6: Tidal volume tracings with sectioning of the nervous system The first cut between the midbrain and pons shows that higher brain centres are not necessary for controlling respiratory movements. At the same time cutting both vagal nerves influences rhythm What effect does it have on depth and rate? (2 Marks). Explain why this happens (1 Mark)

Explanation / Answer

1.

Vagus nerves are important for anaphylactic reactions for respiratory system. Cutting these two nerves cause hypoxemia in patients. The lung starts to function less and take small breaths. This causes reduction in oxygen level. Therefore, the tidal volume gets decreases and rate of breathing increases.

2.

This happens because vagus nerves innervate lungs and hence control it through parasympathetic way. Therefore, cutting them cause disruption in lung’s function.

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