Nervous Systems

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Nervous Systems
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Structure of a Vertebrate Neuron
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Diversity of Nervous Systems
Simple, slow moving animals like hydra have
neurons arranged in a network of bipolar neurons
called a nerve net.
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Basic Tasks of the Nervous System
Sensory Input Monitor both external and
internal environments. Integration Process the
information and often integrate it with stored
information. Motor output If necessary, signal
effector organs to make an appropriate response.
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The Nervous System
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Nervous System
A system that controls all of the activities of
the body.
The nervous system is made of
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The nervous system also allows you to react to a
stimulus.
Stimulus
A stimulus is a change in the environment.
Example A hot stove Or tripping over
a rock
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Your reactions are automatic.
Automatic
Automatic means that you do not have to think
about your reactions.
Example If a bug flies by your eye,
you will blink.
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Brain
An organ that controls your emotions, your
thoughts, and every movement you make.
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Central Nervous System
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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Outer Nervous System
The Outer Nervous System is made of the nerves
and the sense organs.
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Nerve Impulse
Messages carried throughout the body by nerves.
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You have a nerve along your whole arm.
"Funny Bone"
The funny bone is the only place on the arm
where the nerve is not protected. The funny
bone is on the elbow.
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Anatomy of a Neuron

• Cell body functional portion
• Dendrites short extensions that receive signals
• Axon long extension that transmits impulses away

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Nerve Impulse - The Action Potential
Threshold potential will trigger an action
potential or nerve impulse The action potential
is an all-or-none response
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Myelinated Neurons

• Myelin sheathing allows these neurons to conduct
  nerve impulses faster than in non-myelinated
  neurons.

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Saltatory Conduction in Myelinated Axons
Myelin sheathing has bare patches of axon called
nodes of Ranvier Action potentials jump from
node to node
Fig. 48.11
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How does a signal move from one neuron to another?

• A synape divides 2 neurons
• The action potential will not move across the
  synape
• Neuro transmitters
• Released by the signal cell to the receiver cell
• Move by diffusion

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Types of chemical synapse

• Acetylcholine neuromuscular junctions, glands,
  brain and spinal cord
• Norepinepherine affects brain regions concerned
  with emotions, dreaming

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The Nervous System
The Central Nervous System
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The Central Nervous System
The Central Nervous System controls all of the
bodys activities.
The Central Nervous System is made of two
main organs.
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The Spinal Cord
The spinal cord sends messages to the brain.
The spinal cord is the part of the nervous
system that connects the brain to the rest of the
nervous system.
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The Brain
The brain controls everything in the body.
The brain is made of more than 10 billion
nerves!
The brain is divided into three parts and is
protected by the skull.
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The Three Parts of the Brain
The Brain has three main parts
1. The Cerebrum
2. The Cerebellum
3. The Brain Stem
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The Cerebrum
The Cerebrum is the largest part of the brain.
1. The cerebrum controls your thinking.
2. The cerebrum controls your memory.
3. The cerebrum controls your speaking.
4. The cerebrum controls your movement and
identifies the information gathered by your sense
organs.
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The Cerebellum
The cerebellum is below and to the back of the
cerebrum.
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The Brain Stem
The Brain Stem connects the brain to the
spinal cord.
The nerves in the brain stem control your
heartbeat, breathing, and blood pressure.
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The Vertebrae
The vertebrae are the many bones that protect
the nerves in the spinal cord.
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The Outer Nervous System
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Outer Nervous System
The outer nervous system carries messages
between the central nervous system and the rest
of the body.
The Outer Nervous Systems job is to connect
the Central Nervous System to the rest of the
body.
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Outer Nervous System
The outer nervous system is made of the nerves
and the sense organs.
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Reflex
An automatic reaction that happens without
thinking about it.
A reflex happens quickly in less than a second.
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Automatic Nervous System
The outer nervous system controls the bodys
activities that you dont think about.
The outer nervous system controls activities
in your small intestine, your breathing, and your
heartbeat.
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The Senses
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Sense Organs
Sense organs carry messages about the environment
to the central nervous system.
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Sense Organs
The eyes, ears, nose, tongue, and skin are
examples of sense organs.
The sense organs gather information (light,
sound, heat, and pressure) from the environment.
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Environment
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
Vision involves the eye and the brain.
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Parts of the Eye

• Detectors on the Fovea
• Rods
• light intensity and motion sensitive
• Cones
• color sensitive
• The blind spot for the eye is cause by the optic
  nerve.

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Myopia (Near-Sightedness)
People with near-sightedness cannot see clearly
at distance.
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Hyperopia (Farsightedness)
People with far-sightedness cannot see clearly up
close
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When a sound is made, the air around the sound
vibrates.
Hearing
Hearing starts when some of the sound waves go
into the ear.
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Parts of the Ear
There are nine main parts of the ear.
1. Pinna
5. Anvil
2. Ear canal
6. Stirrup
3. Ear drum
7. Cochlea
4. Hammer
8. Eustachian tube
9. Auditory nerve
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Parts of the Ear
The pinna is the part of the ear
that you can see.
The ear canal is the tube between the outside of
the ear and the ear drum.
The ear drum is in the middle ear. It vibrates
when sound waves hit it.
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Parts of the Ear
The three smallest bones in the body, the hammer,
the anvil, and the stirrup, are in the
middle ear.
The hammer gets the vibrations from the eardrum,
then sends them to the anvil.
The anvil passes the vibrations to the stirrup.
The stirrup passes the vibrations
to the inner ear.
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Parts of the Ear
The Eustachian tube controls the amount of
pressure in the ear.
The inner ear is made of
the cochlea and liquid.
The cochlea is in the inner ear. The cochlea
looks like a shell.
The auditory nerve carries the hearing
information to the brain and the brain
tells us what we heard.
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The Ear and Balance
The ear works with the brain to control your
balance.
All of your movements are controlled by balance
and muscles.
The liquid in your inner ear is responsible for
your balance.
The liquid in your ear moves when we move. The
liquid movement sends information to the brain to
tell it how we are moving.
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The sense of touch is located in the skin.
Touch
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.
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
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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Flavors
Tastes and smells work together to
make flavors.
Flavors are the tastes of food and
drinks.
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Addictive Drug Use Tobacco, Alcohol, Illicit
Drugs

• Dr. Robert B. Coambs
• Psy333
• November, 2002

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Pharmacology of Addictive Drugs

• All addictive drugs produce
• Short-term pleasure to some degree
• Long-term negative consequences
• Tolerance physical dependence
• A withdrawal syndrome
• Activation of dopamine neurons in the Nucleus
  Accumbens

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Transmission Across the Synapse
Source Gray
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How Drugs Become Addictive
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Detail of Axon Terminal
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Detail of the Synapse Itself
Neurotransmitter molecules (e.g., Acetylcholine
or Dopamine)
Postsynaptic membrane
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How binding sites work
Binding site
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Neurotransmitter re-uptake helps keep binding
sites clear
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Cocaine inhibits the re-uptake of dopamine
producing effects such as increased heart rate
and blood pressure
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Nicotine fills activates acetylcholine binding
sites producing effects such as increased heart
rate and blood pressure
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What is Addiction?

• All definitions describe behaviour which produces
  positive sensations in the short term, but
  negative consequences in the long term
• A straightforward definition
• Compulsive use
• Loss of control
• Use despite harm

Portnoy
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How People Start Using Drugs

• Genetics
• Predisposing risk factors
• Age 11-22 for onset
• Primitive character structures
• Especially Conduct Disorder
• Peer influence
• Parental influence
• Smoking and alcohol use
• Constricted temporal focus?

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Nicotine Use is Associated With Other Drug Use
Kozlowski, Coambs, et al., 1989
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Some People Never Start

• Factors which reduce risk
• Age 35
• Nuanced character structures
• No Peer influence
• No Parental drug use history
• No other smoking or alcohol abuse
• E.G., the SISAP

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Basic Treatment For Addiction

• Treat the urges directly, if possible
• Establish why the person uses the drug
• What needs are being fulfilled by that drug?
• Find methods to fulfil those needs without the
  drug

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How People Quit Drug Abuse

• Most quit on their own (cold turkey)
• Most use no medication
• Probably those people who can quit easily do so
• Clinicians tend to see the difficult cases
• Ambivalence is normal
• Most quit by age 40

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Relapse Prevention

• Plan for relapse Abstinence Violation Effect
• Relapse is common it is not failure!
• Repeated relapse is associated with success in
  quitting
• Learn from it in next attempt
• Find a way to control urges