A Quick Neuron ReviewMrs. Schlicht

Learning Targets

● To review identifying & defining the parts of the neuron

● To review the steps in which a neuron fires/sends messages.

● To discuss various neurotransmitters and their role in the body

soma

types of neuronsSensory (Afferent)- from senses to your brainMotor (Efferent)- from brain to your body partsInterneurons- in the spinal cord connects the messages from sensory & motor (make reflexes happen)Mirror- reflect what we see (copies the actions of others)- newest neuron still learning about it, no consistent model exists yet

How do neurons communicate? 1. Dendrite receives the message (listens)

2. Soma (cell body) gets the message- send or

not?

3. Message travels down axon (speaker)

4. Action potential (neural impulse): fire signal

-excitatory: fire neuron

-inhibitory: don’t fire neuron

Neurons’ “stages” 1.Resting- inactive neuron …not sending

messages, but could (negative charge inside neuron- positive charge outside=polarization/homeostasis)

2.Action potential- zooms across the axon to send the message

3.(Absolute) refractory period- the neuron can’t send impulses (messages) for 1.2 milliseconds…this is the rest after it sends a message

Depolarization: the initial movement of the action potential...Movement in cell body to axon terminal- Resting Potential to Action

Potential

The All-or-None Response•The idea that either the neuron fires or it does not.•No “half way” about it!•The “strength” of the stimulus doesn’t matter. The intensity is the same.–More neurons may fire, or fire more often (NOT FASTER, but repeat the action more often)•A kiss on the cheek

•A slap to the cheek

It’s Electric!It is an electrochemical process!•Electrical because of impulses inside the neuron.•Chemicals because the neuron (in the synapse)releases chemicals in the form of a neurotransmitters.

Axon terminal buttons make the neurotransmitters.

Sodium Potassium Pump

The Sodium Potassium songI’m a little neuron, short and stout…Here is my dendrite, here is my spout [axon]...When I reach my threshold, hear me shout:“Let the sodium in, and the potassium out!”

Courtesy of the lovely M. Vita

p.54 in book