Introduction

Complexities occurring even with simplest function◦ Example

synapse

Structure of the neuron

Neuron- individual cells in our nervous system that receive, integrate and transmit information.

Components of a neuron:◦ A.) cell body (soma)- contains nucleus and chemical

machinery

◦ B.) Dendrites – Part of neurons that receive information “Branches”

Components of neuron (continued)

◦ C.) Axon- Long thin fiber that transmits signals from cell body to other neurons.

◦ D.) Myelin Sheath- Insulating material that coats an axon. Speeds up transmission Problems if it degrades

Easier way of thinking about axon and myelin sheath

◦ E.) Terminal Buttons- Axon ends with a cluster of these small knobs secreting chemicals known as neurotransmitters.

◦ F.) Synapse – A “Gap” or junction where information is transmitted from one neuron to another.

Summary of neural communication:◦ Dendrites cell body axon (coated with myelin

sheath) terminal buttons synapse at other dendrites(where signal jumps gap)

◦ Process repeats itself

Neural Impulse- Signal sent through neuron

Neuron at rest:◦Slightly negative charge◦Contains ions flowing back and forth

Charge is referred to as Resting Potential- charge when a neuron is not activated

When neuron is activated, channels open allowing in positive ions (+)◦ Charge now becomes positive

Called Action Potential- Brief shift in neuron charge that travels along axon.

Channel closes briefly after firing:◦ Absolute Refractory Period- Minimum length of time

after action potential during which another action potential can’t begin

Neurons either fire or do not (action potentials occur or don’t)

Transmission of signals from one neuron to another (at dendrites) occurs here

At this gap, the arrival of action potential triggers release of neurotransmitters.

Neurotransmitter- Chemical that transmits information from one neuron to another◦ Play role in behavior◦ Specific ones function at specific synapses

Example Neurotransmitters:◦ Dopamine◦ Norepinephrine◦ Serotonin◦ Endorphins

Certain chemicals or drugs can cause increase or decrease in release.

Dopamine- Pleasurable emotions

Norepinephrine- contributes to mood and arousal

Serotonin- plays role in depression

Endorphins- Body’s own internally produced morphine like substance◦ Plays role in pain relief