Respiration Experiment of Rabbit本报告无抄袭现象 组员PURPOSE:To observe the effects of some factors on respiratory movementANIMAL:RabbitMETHOD:Grasp and weight a rabbit, anesthesia.Fixing the rabbit, shear its hair on middle of its neck, make the thachea was detached and thread under it. Insert and fix the cannula Separate the bilateral vagus nerves.Observation items Normal respiratory curve . Breathe in CO2. Hypoxia. Increasing the dead space. Stimulate the central end of vagus.RESULT: DISCUSSION:The medulla oblongata is the main centre of respiratory movement. And maintaining smooth rhythmic respiratory is also involved the lungs stretching reflection and breathing adjustment main centre.Increase the dead space, breathe become deeper and faster. The resistance of respiratory increase, then the traction force of Respiratory muscle increase, the excited of muscle spindle Increase, reach the central by afferent nerve, then, the traction of respiratory muscle is enhanced. Therefore, respiratory movement is enhanced.Increase the concentration of the CO2 gas inhalation, respiratory movement is becoming deeper and faster. There are two ways to achieve.First, the CO2 in blood through the blood-brain barrier with the help of the CA in CSF, the concentration of H+ increase (CO2+H2OH2CO3HCO3- +H+, H+ role of receptors in the respiratory center directly, the respiratory center excitability, through the efferent nerves and respiratory muscle function, respiration movement increase.Second, the elevated CO2 in blood role of the carotid body and aortic body chemoreceptor peripheral, income respiratory center, the respiratory center excised, respiration movement increase.Hypoxia leads the respiratory movement deeper and faster. The CO2 in gas inhalation decrease makes the CO2 in blood decrease, then, respiration movement increase through the two ways witch is mentioned. However, hypoxia can inhibit the central nervous, so hypoxia mainly affects peripheral.Vagus nerve, an afferent nerve of stretching reflex of lung, through the inhibition of central inspiratory neurons in time to adjust the depth and frequency of breathing. Cut off one side of the vagus nerve, inspiratory is extended and the frequency is slow down. At that time, the receptor of stretching reflex of lung cant take the stimulation to the respiratory center, inspiratory change into expiratory is depended on respiratory adjustment center in pons. This is showed as long-suction respiratory.Cut off the other side of the vagus nerve, inspiratory is extended significantly. The stretch reflex of lung is completely useless.Give the center of vagus nerve an electrical stimulation, respiratory become shallow, frequency speed. When the electrical stimulation is given, impulses afferent respiratory center constantly, which Inhibit the central inspiratory neurons. It becomes into expiratory when the inspiratory is not yet complete.CONCLUSION:Under normal circumstances, animals maintain uniform rhythmic breathing movements. Respiratory movement of animals is affected by the stretch reflex of lung, the concentration of O2 CO2 and so on.: