Neurons and Action Potential

Objectives1. Understand the anatomy of a neuron and how

signals travel along neurons. • Describe parts and function of neuron and build

complete neuron.

2. View the concept “Fire together, wire together” and graph signal strength. • Use built neuron to fire to another neuron and

strengthen connection.

3. Visualize the idea of creating an action potential.• Show how neurons need to reach threshold to fire

action potential.

Neurons and Action Potential

If a neuron fires and activates another neuron then the connection between those neurons is strengthened.

Neurons:

• Are cells of the nervous system

• Process and transmit information electrically and chemically

• Produce voltages

• Have a nucleus and other organelles and are surrounded by a cell membrane

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Neurons and Action Potential• Dendrites bring information to the cell body and axons

take information away from the cell body.

• Signals travel down the axon to the terminal branches.

• A typical synapse is a contact between the axon of one neuron and a dendrite of another.

Neurons and Action Potential• When you learn, messages travel from one neuron to

another, over and over making connections between neurons.

• Information flows from one neuron to another across a synapse, which is a gap that separates neurons.

• Neurotransmitters from the presynaptic region flow to receptors at the postsynaptic region.

Neurons and Action Potential• When a neuron is not sending a signal it is at resting

potential.

• Action potential occurs when a neuron sends info down an axon.

• When a neuron receives a message from other neurons, the neuron is depolarized.

• The neuron must reach threshold to fire an action potential.

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Neural Tissue EngineeringNeural tissue engineering is a sub-field of tissue engineering.

Neuronal tissue grafts and scaffolds are implanted to promote nerve regeneration and to repair nerve damage.

Current Research:• Spinal cord regeneration• Inflammation and fibrosis elimination

Student Activity

Goal:

Build a neuron and create a setup that will allow neurons to fire to other

neurons.

Student Activity

Materials:• Clay

• LED

• Copper wire strips

• Pennies

• Paper clips

• Alligator clips

• Voltmeter

• Neurotransmitters

Student Activity

Procedure:1. Create your own neurons using clay, wire and LED.

The wire will act as dendrites and axon branches. The LED will be placed in the cell body of the neuron with leads sticking out.

2. Insert a paper clip and penny into a neurotransmitter.

3. Using alligator clips make a connection between two neurons by sending a neurotransmitter from one neuron to another.

Student Activity5. Using the voltmeter measure the voltage. If the LED

is lit threshold has been reached and that neuron can fire an action potential.

6. Keep adding neurotransmitters and measuring the voltage. If the LED gets brighter the connection between the neurons is strengthened.

7. Graph the voltages.

Student Activity

Questions:• What are the different parts of a neuron and what are

their functions?

• What direction do neurons communicate?

• What are neurotransmitters?

• How many neurotransmitters did it take to reach threshold?

• What happened to the connection between the neurons as you added more neurotransmitters?

• Did the voltages increase or decrease as you added neurotransmitters?