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Nervous System Model Building

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Nervous System Model Building

Mission: build and test a model of how the nervous system carries a message. Use the self-contained case study and diagrams below. Answer in your own words; for the model task, you may use paper, string, or other safe classroom materials.

Case file: the hot baking tray

Ari accidentally touches the edge of a hot baking tray. Receptors in the skin detect the heat and send a signal along a sensory neuron to the spinal cord. A relay neuron passes the message on. A motor neuron carries instructions to muscles in the arm, which contract and pull the hand away. The spinal cord organises this quick response; the brain receives information about the event too. A neuron is a specialised cell that carries information. Signals travel within a neuron as electrical impulses. At a junction between neurons, chemicals carry the message across a tiny gap called a synapse.

1.Using the case file, put these events in the order they happen: muscles pull the hand away; skin receptors detect heat; motor neuron carries instructions; sensory neuron carries the signal to the spinal cord; relay neuron passes the message on.

2.Why can pulling a hand away from something hot happen before a person consciously decides to move?

The spinal cord organises a rapid response, while the brain is also informed.
The muscles detect heat and send instructions directly to the skin.
The brain is not involved in any way.
The signal travels from the muscles to the receptors.

3.Mark each action as a reflex (R) or a deliberate action (D): blinking when a speck approaches the eye; choosing a song to play; pulling away from a hot surface; tying a shoelace.

4.Sketch a neuron model in the box. Label the dendrites, cell body, axon, myelin sheath and axon terminals. Add arrows to show the direction a signal travels. Beside the sketch, name one safe material you could use to represent each part.

Draw and label your model here.

5.Match each neuron part to its main job.

Dendrites
Cell body
Axon
Myelin sheath
Axon terminals

Contains the nucleus and maintains the cell
Carries an impulse away from the cell body
Pass a message towards the next cell
Receive signals from other cells
Insulates the axon and helps impulses travel faster

6.Which sequence best describes the direction of an impulse through a typical neuron?

Axon terminals → axon → cell body → dendrites
Dendrites → cell body → axon → axon terminals
Cell body → dendrites → axon terminals → axon
Myelin sheath → nucleus → dendrites → muscles

7.A message reaches the end of one neuron's axon. Explain how it can continue to the next neuron across a synapse.

8.Classify each part of the hot-tray response as part of the central nervous system (CNS) or peripheral nervous system (PNS): brain; spinal cord; sensory neuron in the arm; motor neuron travelling to an arm muscle.

9.A student represents an axon with string and myelin with short sections of drinking straw placed around it. Explain what each material represents and one way this model is useful. Give one limitation of the model.

10.If myelin is damaged, how might this affect messages travelling along an axon? Use the role of myelin in your explanation.