MA+Nervous+System+HW

1. What are the two major divisions of the nervous system? The two major divisions are the central nervous system and the peripheral nervous sytem. 2. What are the three types of neurons? The three types of neurons are sensory neurons, interneurons, and motor neurons. 3. What are the three parts of a neuron? The three parts of a neuron are the dendrites, the cell body, and an axon. 4. What is a nerve impulse and how does it spread (this requires a long answer). A nerve impulse informs the nervous system with information. The resting condition is when there is more Na+ outside of the axon and more K+ inside the axon and there is no activity or "impulse". Action potential is when the sodium gates open up and there is a change in polarity across the axonal membrane due to a nerve impulse.. Depolarization happens when Na+ moves to the inside of the axon. Then the potassium gates open up leading to K+ moving to the outside of the axon. 5. Since neurons don't physically touch, how is an impulse transmitted from one neuron to the next? When a neurotransmitter is released into a synaptic cleft, transmission of a nerve impulse occurs. Binding of the neurotransmitter to receptors in the receiving membrane causes excitation or inhibition. Integration is the summing of excitatory and inhibitory signals. 6. What structures compose the central nervous system? The spinal cord and the brain. 7. What are the two main functions of the spinal cord? Conduction to and from the brain and it carries out reflex actions. 8. What are the four major parts of the brain and the general function of each? Cerebrum: Sensation, reasoning, learning, memory, language, and speech occur here. Sends out motor commands. Diencephalon: controls homeostasis and sends sensory input to the cerebrum. Cerebellum: coordinates skeletal muscle contractions Brain Stem: controls breathing and heartbeat.