Download Unit 3A Nervous System - Teacher Version

Neurons
I bet your neurons are all fired
up now!
The Nervous System
Neuron = 1 cell
• Example: Afferent,
Efferent and
Interneurons

Nerve = a bundle of
neurons
•
Example: Optic Nerve
Types of Neurons
• Efferent (Motor) Neurons
carry outgoing messages from the brain
and spinal cord to the muscles and glands
• Interneurons -
neurons within the
brain and spinal cord that communicate
internally and between sensory inputs
and motor outputs
• Afferent (Sensory) Neurons carry messages from tissues and sensory
organs to the brain and spinal cord for
processing
Think Pair Share
• Explain which neuron’s are at
work when you swat a mosquito
• Which neurons are at work when
you pick up a fork?
Warmup
• Think of an example (not one we discussed in
class) where you are using
a) Afferent neurons
b) Efferent neurons
c) Interneurons
Neurons
Neurons
Neurons
Neurons
Neurons
Neurons
Neurons
How neurons communicate
Electro-Chemical process
1. Electrical – within a neuron
–
Action Potential – brief electrical charge that
sends a message down the neuron
•
Information is pushed through the axon based on process
of positive and negative charges of electrical atoms (ions)
– Potassium (K+), Sodium (Na+), Chloride (Cl-)
2. Chemical – between neurons
–
Neurotransmitters (chemicals) travel across the
synapse: different ones send different messages
on to the next neuron
•
Neurotransmitters can either excite (fire) or inhibit
(prevent firing)
• Messages are sent at a speed of 2-200 mph
How does a neuron fire
Step 1 : Resting potential – neuron is charged and ready to fire (-70mv)
– Polarized – positive outside, negative inside
(Na+)
(K+)
– Selectively permeable – gates do not allow sodium ions to pass through the
cell membrane
Step 2: Threshold – the minimum energy needed to generate an action potential
(-55mv)
–
Excitation- the process of making a neuron more likely to generate an
action potential (excitatory neurotransmitters binding to receptors) must
be greater than
– Inhibition – the process of making the neuron less likely to generate an
action potential (inhibitory neurotransmitters binding to receptors)
Step 3: Action potential – brief electrical charge that travels down the neuron
–
Depolarizes - Sodium (Na+) rushes in creating a positive charge on the
inside of the cell membrane.
– All or None Response – neurons can only send message in one direction at
the same speed and strength
– Repolarization - Potassium (K+) flows out of the cell membrane, reversing
the polarity
– Step 4: Refractory period - the recharging period that must occur to
ready a neuron to generate another action potential
– Sodium/Potassium pumps push Sodium (Na+) out and Potassium in (K+)
bringing axon back to resting potential
Action Potential
Electrical Transmission –
The Action Potential
http://www.outreach.mc
b.harvard.edu/animatio
ns/actionpotential_shor
t.swf
Between Neuron Communication
• Neurotransmitters – the chemical messengers that carry
information across the synapse between one neuron and then
next are released from terminal buttons on the sending neuron
Can be:
– Excitatiatory Neurotransmitters – make the neuron receiving
neuron more likely to generate an action potential
• Glutamate
– Inhibitory Neurotransmitters – make the neuron receiving
neurotransmitters less likely to generate an action potential
• GABA
• Synapse – the small gap between neurons which
neurotransmitters travel across to send a message to the
receiving neuron’s dendrites
• Reuptake – the process of the sending neuron’s terminal buttons
taking back excess neurotransmitters from the synaptic gap
How do neurons communicate with
each other?
The chemical process
How Neurons Communicate
How Neurons Communicate
How Neurons Communicate
How Neurons Communicate
How Neurons Communicate
Synaptic Transmission
http://learn.genetics.utah.edu/
content/addiction/crossingdivi
de/
Think Pair Share
1. Put the following terms in order as they occur.
2. Identify which are part of the “electro” (E) part and
which are part of the “chemical part” (C)
3. Briefly describe the electro-chemical process of
neural transmission:
– Resting potential
– Synapse
– Action potential
– Repolarization
– Refractory period
– All-or-None
– Threshold
– Excitation
– Inhibition
– Reuptake
– Depolarization
1.
2.
3.
4.
5.
A brief electrical charge that travels
down the axon of a neuron is called
the
Synapse
Agonist
Action Potential
Resting Potential
Refractory period
Table
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
The function of dendrites is to
1. receive incoming signals from other
neurons.
2. release neurotransmitters into the
spatial junctions between neurons.
3. coordinate the activation of the
parasympathetic and sympathetic
nervous systems.
4. control pain through the release of
opiate-like chemicals into the brain.
5. transmit signals to other neurons.
0%
1.
Table
0%
0%
2.
3.
0%
0%
4.
5.
The movement of positively charged
ions across the membrane of a neuron
can produce a(n)
1.
2.
3.
4.
5.
Action potential
Synapse
Neurotransmitter
Myelin sheath
Interneuron
Table
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
The axon of a resting neuron has gates that do
not allow positive sodium ions to pass through
the cell membrane. What is this characteristic
called?
1. Myelin sheath
2. Threshold
3. Selective
permeability
4. Action potential
5. Refractory period
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
Table
The minimum level of stimulation
required to trigger a neural impulse is
called the
1.
2.
3.
4.
5.
Reflex
Threshold
Synapse
Action potential
All-or-none
response
Table
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
Reuptake refers to the
1. movement of neurotransmitter
molecules across a synaptic gap.
2. release of hormones into the
bloodstream.
3. inflow of positively charged ions
through an axon membrane.
4. reabsorption of excess
neurotransmitter molecules by a
sending neuron.
5. the ending of the refractory
period.
0%
1.
Table
0%
0%
2.
3.
0%
0%
4.
5.
Drugs can be…..
• Agonists- mimic
neurotransmitters
• Antagonists- block
neurotransmitter
• Reuptake Inhibitors- block
the reuptake
Acetylcholine (ACH)
• Motor movement, memory
and learning.
• Too much and you will….
• Too little and you will…
• Alzheimer’s disease – lack of
AcH
• Black widow – increased AcH
• Botox – blocks AcH
• Curare – blocks AcH
Dopamine
• Motor movement and
alertness/attention,
emotion, rewards.
• Parkinson’s Disease
(too little)
• Schizophrenia (Too
much)
Serotonin
• Emotional
State/Mood, Sleep,
• Depression - Lack of
serotonin
• Anxiety
• OCD
Endorphins
• Pain control/perception,
mood booster
– Examples:
– Allows you to continue playing
in the game when you sprain
your ankle
– “endorphins make you
happy…happy people don’t kill
their husbands” – runners high
Norepenephrine
• Fight or flight
response – increased
heart rate,
breathing, pupil
dilation,
• High Blood Pressure
• Anxiety
GABA
• Inhibition of Brain
Activity
– Major inhibitory
neurotransmitter - keeps
the neuron from firing
(slows CNS)
• Undersupply linked to
seizures, tremors,
insomnia
• Alcohol consumption
causes an increase in
GABA
Glutamate
• Excitation of Brain
Activity
– Major excitatory
neurotransmitter Meaning…
It causes neurons to
fire – overactive CNS
• Migrains
• MSG
Antidepressants such as Prozac
target which neurotransmitter?
1.
2.
3.
4.
5.
A. serotonin.
B. glutamate.
C. GABA.
D. acetylcholine.
Dopamine
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
Lindsey has just played a long volleyball match after injuring
her ankle in the first game, but feels little fatigue or
discomfort. Her lack of pain is most likely caused by the
release of
1.
2.
3.
4.
5.
Glutamate
Dopamine
Acetylcholine
Endorphins
Insulin
Table
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
A person with schizophrenia may have an overactive dopamine
system. Drugs used to treat this disorder prevent the action of
dopamine by keeping it from binding to its receptors. These
drugs are
1.
2.
3.
4.
5.
Agonists
Reuptakes
Action Potentials
Antagonists
Synapses
Table
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
Neurotransmitters that bring a
neuron closer to firing are called
1.
2.
3.
4.
5.
Agonist
Antagonists
Inhibitory
Reuptake
Excitatory
Table
0%
1.
0%
0%
2.
3.
0%
0%
4.
5.
Agonists and Antagonists
http://thebrain.mcgill.ca/flash/i/i_03/i_03_m/
i_03_m_par/i_03_m_par_cocaine.html#dro
gues
Agonist and Antagonists
Examples:
Agonists – Opiate Drugs i.e. Heroin,
Morphine (Mimic Endorphins)
Black Widow Spider Venom (mimics AcH)
Antagonists – Botulin (AcH), Curare
(AcH) (block neurotransmitters)
The Nervous System
Central Nervous System
• Brain
• Spinal chord
• Interneurons
Peripheral Nervous System
• All nerves that are
not encased in bone.
• Everything but the
brain and spinal
cord.
• Motor and Sensory
Neurons
• Autonomic and
Somatic
Somatic Nervous System
• Controls voluntary
muscle movement.
• Uses motor
(efferent) neurons.
• What are two
examples of you
using your Somatic
Nervous System
Autonomic Nervous System
• Controls the automatic
functions of the body.
– Lungs, stomach, intestines,
liver, kidney, heart
• sympathetic and the
parasympathetic
• What are two examples
of you using your
Autonomic Nervous
System
Sympathetic Nervous System
• Fight or Flight Response.
– Arouses and expends
energy
• Causes:
– Increase in heart rate,
breathing, dilates pupils,
slows down digestion,
relaxes bladder
• What are two examples
of you using your
Sympathetic Nervous
System
Parasympathetic Nervous System
• Rest and Digest Response
• Automatically slows the body
down after a stressful event.
• Causes:
– Heart rate and breathing slow
down, pupils constrict and
digestion speeds up.
• What are two examples of
you using your
Parasympathetic Nervous
system
The peripheral nervous system
consists of:
1.
2.
3.
4.
A.
B.
C.
D.
association areas.
the spina chord.
the reticular formation.
sensory and motor neurons.
Table
0%
1.
0%
2.
0%
3.
0%
4.
As Allison reaches for a box in her garage, out jumps a big spider. Her heart
immediately begins to race as she withdraws her hand, but soon she realizes
that the spider is harmless, and she begins to calm down. Which part of her
nervous system is responsible for brining her back to a normal state of
arousal?
1. A. sympathetic nervous
system
2. B. somatic nervous system
3. C. parasympathetic nervous
system
4. skeletal nervous system
0%
1.
Table
0%
2.
0%
3.
0%
4.
Reflexes
• Reflex - a simple, automatic,
inborn response to a sensory
stimulus
– Normally, sensory (afferent)
neurons take info up through
spine to the brain.
– Some reactions occur when
sensory neurons reach just the
interneurons in the spinal cord
= reflex
– Survival adaptation.
A Simple Reflex
Think Pair Share
• Which part of your nervous system and which
neurons would you rely on most heavily to
cross the street?
• Which part of your nervous system and which
type of neuron’s would you use to when Ms.
Short arrives at your class and calls you out to
the hall, then sends you back to class.
A Simplified Neural Network
Neural Network – interconnected cluster of
neurons in the CNS
Neurons learn to work together as a team.
Neurons that fire together, wire together =
learning
The Endocrine System
•A system of glands that secrete
hormones.
•Similar too Neurotransmitters
Neurotransmitters Hormones
Neurotransmitters
Location
Nervous System
Blood
Stream/Endocrine
System
Speed
Very fast – fraction
of a second
Travel from neuron
to neuron
Slow – several
seconds
Travel from gland to
tissue
Hormones
Pineal Gland – controls
circadian rhythm (melatonin)
Master Gland:controls other
glands
Responsible
for releasing
(growth
hormone
Controls
pituitary gland
Sends info to
CNS
Thyroxine
Overactive =
skinny
Underactive = fat
Parathyroid hormone
Adrenaline or
epinephrine and
norepinephrine
cortisol
Insulin
Too Low =
hyperglycemia
Too high =
hypoglycemia
Estrogen
Testosterone
Figure 3A.11 The endocrine system
© 2011 by Worth Publishers