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Brain
WHAT PARTS DO YOU KNOW THAT
ARE IN THE NERVOUS SYSTEM?
Spinal Cord
Peripheral Nerves
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Classification of the Nervous System
Central nervoussystem (CNS):
BrainSpinal cord
Peripheral nervoussystem (PNS):
Nerves outside the
brain and spinal cord
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Functions of the Nervous System
Sensory input gathering information
To monitor changes occurring inside andoutside the body
Integration - To process and interpretsensory input and decide if action isneeded
Motor outputA response to stimuli
Activates muscles or glands
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The Peripheral Nervous System
Sensory (afferent) division - Nervefibers that carry information tothe centralnervous system
Motor (efferent) division -Nerve fibers
that carry impulses away fromthe central
nervous system.
Somatic system:
voluntary
Autonomic system:
involuntary
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Autonomic Nervous System
The involuntary branch of the nervoussystem
Consists of only motornerves
Divided into two divisions
Sympathetic divisionfight or flight response
Parasympathetic divisionhousekeeping
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The Central Nervous System is made of the brain and the spinal
cord.
The Central Nervous System controls everything in the body.
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Nervous System Histology
Neurons = nerve cells
Cells specialized to transmitelectrochemical messages
Major regions of neurons
Cell body nucleus and
metabolic center of thecell
Processes fibers thatextend from the cell body
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Neuron Anatomy
Dendrites conduct impulsestoward the cell body
Cell body (soma): containsorganelles & Nissl
substance (specializedrough ER)
Axons conduct impulsesaway from the cell body
Schwann cells produce myelinsheaths in jelly-roll likefashion
Nodes of Ranvier gaps inmyelin sheath along the axon
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Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors
Cutaneous sense organsReceptors detect stretch or tension
Interneurons (association): connector
Motor (efferent) neurons
Carry impulses from the central nervous
system
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What makes up the brain, the spinal cord or
your peripheral nerves?
Neurons are the cell
Cell body
Nucleus
Axon
Dendrite QuickTime and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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Key NoteNeurons perform all of the communication,
information processing, and control functions
of the nervous system.
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Someone getting on your nerves?
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How are neurons connected?
Synapses!!
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Why are neurons connected?
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More neuron connections!
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General Organization of the nervous system
Brain & spinal
cord
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How does the Synapse carry the signal?
1. Electrical current travels down the axon2. Vesicles with chemicals move toward the membrane - what is
that called?
3. Chemicals are released and diffuse toward the next cells
plasma membrane4. The chemicals open up the transport proteins and allow the
signal to pass to the next cell -
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1
23 4
The synapse carries a signal from cell to cell
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Are all neurons equal in size? Brain vs spinal cord vs peripheral nerves?
About how many neurons are in the human brain? 100 billion
1 billion
around 15 feet
About how many neurons are in the spinal cord?
How long do you think the longest axon in the world is?
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How many synapses
are in one neuron?1,000 to 10,000!!
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This science is called Neurobiology Looking at the actual cells - how do they work?
Looking at the connections - how and when do they work?
Looking at what can change normal cells and connections
Looking at diseases that occur in the brain
One of the largest areas still unknown
Neurons connecting!
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What do you think can change
neurons and their connections? Accidents
Drugs
Alcohol Disease
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Accidents
Physical injury of your neurons
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Drugs and alcohol bind important receptors on neurons
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Repeated binding causes the neuron to die
D d h
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Drugs = neuron death
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Parkinson's Disease
ALS - Lou Gehrigs Disease
Huntingtons Disease
Multiple SclerosisAlzheimer's
Cerebral Palsy
Epilepsy
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100 Billion or so neurons - whats the
problem with some of them dying?
Cells multiply all the time
- will your neurons?
Does everyone react the
same way to accidents, or
drugs and alcohol?
Do all organisms react the
same to all stimulus?Which of your activities
use your neurons?
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Specialized Area of the Cerebrum
Figure 7.13c
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Cranial Nerves
12 pairs of nervesthat mostly serve thehead and neck
Numbered in order,front to back
Most are mixednerves, but threeare sensory only
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* The Outer Nervous Systems job is to connect the Central
Nervous System to the rest of the body.
* The outer nervous system carries messages between the central
nervous system and the rest of the body.
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* The outer nervous system is made of the nerves and the sense
organs.
EarEyeSkin
Nerves
Tongue
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* An automatic reaction that happens without thinking aboutit.
* A reflex happens quickly in less than a second.
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* The outer nervous system controls the bodysactivities that you dont think about.
* The outer nervous system controls activities in your small
intestine, your breathing, and your heartbeat.
controls
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Sense organs carry
messages about the
environment to the central
nervous system.
The eyes, ears, nose,
tongue, and skin are
examples of sense organs.
The sense organs gatherinformation (light, sound,
heat, and pressure) from
the environment.
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The environment is
everything outside the
body.
The sense organs gather
information from
outside the body, then
send the messages to
the brain.
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Vision is your ability to see.
Vision involves the eye and the brain.
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The eye is one of your sense organs.
The eye is made of the iris and thepupil.
The eye gathers pictures and sends them to the brain.
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The colored part of the eye is the iris.
The black part of the eye is the pupil.
The pupil becomes larger and smaller
as it controls the light coming into the
eye.IrisPupil
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When a sound is made, the air around the sound vibrates.
Hearing starts when some of the sound waves go into the
ear.
h f h i l d i h ki
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The sense of touch is located in the skin.
The nerves in the skin allow us to feel texture,
pressure, heat, cold, and pain.
Texture is how something feels.
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The nose controls your sense of smell.
The nose is able to smell 80 different kinds of smells.
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Your sense of taste comes from the taste buds in the tongue.
Taste buds are the parts on the tongue that allow
us to taste.
The four kinds of taste buds are sweet,
sour, bitter, and salty.
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Tastes and smells work together to make flavors.
Flavors are the tastes of food and drinks.