The Nervous System: Basic Structure

Lesson 6-1

Objectives:Identify Parts of the Nervous SystemDescribe the functions of the Nervous System

How the Nervous System Works

2 parts to the nervous systemCentral nervous system- brain and spinal cordPeripheral nervous system- branches of nerves that reach other parts of the body

How the Nervous System Works

All parts of nervous system protected

Brain- skullSpinal cord- vertebraeNerves-sheathing

NeuronsName for a nerve cell

Like a flame travels over firecracker fuseReusable

Nerves send a signal whenever they are stimulated past a minimum pointUse the All-Or-None Principal- A neuron will fire completely or not at all.

Parts of a neuronCell Body-Dendrites- receive impulsesAxons- carries impulses away from the cellMyelin- insulates and protects the axon

In multiple sclerosis, the myelin sheath is destroyedSpeeds transmission of impulses

Axon terminals- branch out at end of axon

The Neuron ConnectionThe Space between neurons is called the synapseChemicals called neurotransmitters carry the impulse across the gap.

They can excite the next neuron or cause it to stop (inhibition)

The Neuron ConnectionMany different types of neurotransmitters

Norepinephrine- involved with memory and learningEndorphines- inhibit pain

Responsible for runner’s high

Ach- involved with movement

The neuron ConnectionMany diseases linked to neurotransmittersAlzheimer’sSchizophreniaParkinson’s diseaseDepression

The Neuron ConnectionOther nervous diseases

AutismDyslexiaMultiple sclerosisAlzheimer’s diseaseTourette’s syndromeBipolar disorder

Neuron ActivityAscending tracts carry impulses to the brainDescending tracts carry impulses away from the brain

Neuron ActivityAfferent or sensory neurons-relay messages from the sense organs to the brainEfferent or motor neurons-send signals from the brain to glands and musclesInterneurons- carry impulses between neurons in the body

Voluntary and Involuntary Activities

Somatic Nervous System is voluntary

You can control

Autonomic Nervous System is involuntary

You can’t controlCan be divided into two parts

Autonomic Nervous System

SympatheticDeals with emergencies and strenuous activityIncreases heart rate and blood pressure

ParasympatheticWorks to conserve energyReduces heart rate and blood pressure

Receptors tell the autonomic system what to do