Nervous System

Topics: Neuron, Action potential, Nervous system Pages: 4 (999 words) Published: June 6, 2013
Nervous System Review Sheet

1. List three functions of the nervous system and give a specific example of each. • Reception of stimuli from environment (internal or external) and relay of info to CNS (Sensory division of PNS) – e.g. Receptors in your ear send a signal to the brain when the bell rings. • Integration of stimuli to decide on a response (CNS) – e.g. Your brain receives the signal that the bell is ringing, along with signals from your eyes that tell you it is time for class to end and decides you should get up and move to your next class. • Signaling effectors to produce a response (Motor division of PNS) – e.g. Your brain sends a signal to the muscles in your legs telling them to contract so you can stand up.

2. Refer to the diagram below to answer these questions:

a) Identify the parts labeled a and b and describe their functions. a = dendrites
b = axon

b) What is c?
c = myelin sheath

c) How would a signal travel through this neuron differently if c were not present? The myelin sheath is a layer of insulation. It forces the nerve impulse to leap from node to node as shown above. This allows the nerve impulse to travel much faster. If the myelin sheath were missing, the nerve impulse would travel at a much slower speed.

d) What is d? Explain what happens when an action potential reaches d. The structures labeled d are synaptic knobs. When an action potential reaches the knobs, they release neurotransmitters that carry the signal across the synapse. These neurotransmitters usually work by binding to receptor proteins in the membrane of the receiving neuron. This binding opens gates that allow sodium ions to enter the cell.

3. Name two ways in which the structure of a neuron is well adapted to perform the functions of the nervous system. A neuron’s structure is well adapted to the function of sending and receiving signals in many ways: • A...
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