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