Question

Instructions: Please answer the following questions to the best of your abilities. Write complete sentences to clearly communicate your ideas. Do not change the format of the document. Due to the school’s computer systems only Microsoft Word or PDF documents are accepted. Submit the completed assignment by uploading it to blackboard.

1. Sensory Neuron enter the CNS through the dorsal horn of the spinal cord. Is also called ?

2. Motoneurons leave the CNS through the ventral horn of the spinal cord, also called?

3. Mention the two main divisions of the Nervous System.

4. Explain – in detail- the generation and propagation of an action potential.

5. Explain - in detail - the all or none principle of motor units.

6. Name and explain the properties of the 3 different Motor Unit types.

Answer 1

1.Sensory Neuron enter the CNS through the dorsal horn of the spinal cord is also called dorsal root ganglion neurons or afferent neurons.

2.Motoneurons leave the CNS through the ventral horn of the spinal cord, also called as the ventral root ganglion neurons or efferent neurons.

3.The two main divisions of the Nervous System- central nervous system and peripheral nervous system. The central nervous system composed of the spinal cord and brain where as the peripheral nervous system composed of the nerves which runs all around the body.

4.The generation of the action potential initiates at the axon hillock, the electric stimulation cause the opening of voltage gated sodium channels and influx of the sodium inside the cells cause the change the negative charge of the cell inside into positive ,reults into the depolarisation.Upon reaching to the threshold, action potential will be generated named as 'all or nothing' principle.When cell will be completely depolarised, the sodium channel will close and the potassium channel will open to counterbalance the increases positive charge inside the cells, the potassium ion will cause the recuction in their electrochemical gradient outside the cell. Thus, it will result into the resting membrane potential due to potassium ion moving out of the cell and there will be decrease in membrane potential.Following to that repolarisation will cause the increase in the resting membrane potential ,results into the more negative potential called as hyperpolarisation. Just after the action potential, it enters into the inactive phase called as the refractory period where sodium channel closes regardless of membrane potential. Thus,the  action potential propagated via the axon of neurons through local currents. These currents follows the depolarization causes depolarisation of the adjacent membrane and the action potential furthers gets produced once reaches threshold.