Transcript The Nervous System: Basic Structure

The Nervous System: Basic
Structure
Lesson 6-1
Objectives:
Identify Parts of the Nervous System
Describe the functions of the Nervous
System
How the Nervous System
Works
2 parts to the nervous system
Central nervous system- brain and spinal
cord
Peripheral nervous system- branches of
nerves that reach other parts of the body
How the Nervous System
Works
All parts of nervous system protected
Brain- skull
Spinal cord- vertebrae
Nerves-sheathing
Neurons
Name for a nerve cell
Like a flame travels over firecracker fuse
Reusable
Nerves send a signal whenever they are
stimulated past a minimum point
Use the All-Or-None Principal- A neuron
will fire completely or not at all.
Parts of a neuron
Cell BodyDendrites- receive impulses
Axons- carries impulses away from the cell
Myelin- insulates and protects the axon
In multiple sclerosis, the myelin sheath is
destroyed
Speeds transmission of impulses
Axon terminals- branch out at end of axon
The Neuron Connection
The Space between neurons is called
the synapse
Chemicals called neurotransmitters
carry the impulse across the gap.
They can excite the next neuron or cause it
to stop (inhibition)
The Neuron Connection
Many different types of
neurotransmitters
Norepinephrine- involved with memory and
learning
Endorphines- inhibit pain
Responsible for runner’s high
Ach- involved with movement
The neuron Connection
Many diseases linked to
neurotransmitters
Alzheimer’s
Schizophrenia
Parkinson’s disease
Depression
The Neuron Connection
Other nervous diseases
Autism
Dyslexia
Multiple sclerosis
Alzheimer’s disease
Tourette’s syndrome
Bipolar disorder
Neuron Activity
Ascending tracts carry impulses to the
brain
Descending tracts carry impulses away
from the brain
Neuron Activity
Afferent or sensory neurons-relay
messages from the sense organs to the
brain
Efferent or motor neurons-send signals
from the brain to glands and muscles
Interneurons- 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 control
Can be divided into two parts
Autonomic Nervous System
Sympathetic
Deals with emergencies and strenuous
activity
Increases heart rate and blood pressure
Parasympathetic
Works to conserve energy
Reduces heart rate and blood pressure
Receptors tell the autonomic system
what to do