Download Nervous System WS (handed out after section exam)

Name: ____________________________
NERVOUS SYSTEM
Use pages 322-323, 329 (9 ed.) and the glossary or pages 318-319, 335 (10th ed.) of your text to
complete the following work.
th
1. Define the following terms:
Neurons:
3 parts of a neuron:

Dendrite:

Cell body:

Axon:
Nerve impulse:
Stimulus:
Receptors:
Effector:
Sensory neuron:
Interneuron:
Motor neuron:
Central nervous system (CNS):
Peripheral nervous system (PNS):
2. Label the following diagram of the 3 types of neurons:
3. On the diagram in question 2, use arrows to show the direction of the nerve impulse through the
3 types of neurons.
4. Complete the following table by observing the diagram you just labelled & using the textbook:
Sensory Neuron
Interneuron
Motor Neuron
Structure
______ dendrite
Short ______
Function
Conduct impulse____ Conducts impulse____
__________________ ___________________
__________________ ___________________
Conduct impulse to
_______________ (gland or
_________)
Location
Cell body and dendrite Entirely within _______
are ____________ of ________________
the spinal cord
___________________
_________ are located in
spinal cord
Cell body in _______
________________
Axon is _____________
spinal cord
______ dendrite
Long or short axon
Short _____________
Long _______
Name: ____________________________
5. Myelin Sheath:
a. What is the myelin sheath?
b. What is the name of the type of neuroglia cell that makes the myelin sheath?
c. What substance makes up the myelin sheath?
d. How does the myelin sheath form?
e. What are the nodes of Ranvier?
f. What part of the neuron is usually wrapped in myelin sheath?
 The myelin sheath is responsible for saltatory conduction / transmission. This is where the
electrical impulses jump from one node of Ranvier to the next node. This increases the speed
of the nerve impulse.
 The speed increases because the myelin sheath acts as an insulator, preventing ion loss from
occurring.
6. Neurons are organized into circuits: receptor cells  sensory neurons  interneuron (CNS)
 Brain  interneuron  motor neuron  effector cells (muscle or gland)
There is another circuit called the reflex arc:
Explain the path of a reflex arc (fig. 17.8 p. 329).
7. What is a reflex?
8. Use number to put the following events about the reflex arc in the correct order:
____Impulse causes the muscle to contract
____Impulse reaches interneuron dendrite
____Impulse splits: one axon to brain, one axon to motor neuron dendrite
____Impulse travels along the motor axon
____Impulse travels along the sensory axon
____Impulse travels along the sensory dendrite
____Impulse travels along the motor dendrite
____Stimulus causes and action potential in the sensory receptor