Transcript The Nervous System

Extra Credit Opportunity
(during Spring Break)
Research a Neurological Disorder (up to 25 pts. Possible)
-15 pts. Trifold Display with all Questions & Concepts
-5 pts. Brief Presentation (3-5min) of your disorder
-5 pts. Peer voting of the best display (0-5 pts. poss.)
**If you are planning on presenting you must highlight
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accordingly.
*Presentations will begin this Friday (chosen randomly).
Introduction to the Nervous System
Alzheimer’s:
-Over 4 million American affected
-Ronald Reagan was diagnosed with it
-Mental and performance tests are conducted
-Plaques become present in the brain
Symptoms include:
-memory loss (forgetfulness)
-confusion & frustration
-depression
Tropicamide-causes pupils to dilate with Down’ Syndrome
individuals and people with Alzheimer’s disease
The Nervous System
• Chapter 10
-Structure of a Neuron
-Neuroglial cells
-Classifying Neurons
-Nerve Conduction
-Regeneration
-Synaptic Potentials
-Reflex Arcs
Homework (Mon. 4/16)
• Read Pgs. 356 – 360 in Chapter
• Printout the Study Outline for Chapter 10
http://highered.mcgraw-hill.com/sites/0072919329/student_view0/
• Do Pgs. 10-1 & 10-2
Introductory Questions #1
1)
2)
3)
4)
5)
6)
7)
8)
After reading the introduction in chapter 10, name the disorder
that our ex-president Ronald Reagan had. How many American
are estimated to have the same disorder? What are some of the
symptoms of this disorder? How can this disorder be diagnosed?
What drugs are used?
Another name for a nerve cell is:
.
There are TWO types of cells that make up the neural tissue.
Name them
How do nerve cells transmit information (generally)?
How do neuroglial cells differ from typical nerve cells?
What is the name of the small spaces that exist between the
neurons? Can you give an example of a chemical that can be
found in this space?
How do we classify neurons? What two criteria do we use?
How many different types of neuroglial cells are there? Name
them.
Characteristics of the Nervous System
• Composed of Blood, connective tissue, and neural
tissue
• Two types of nerve cells: Neurons & Neuroglial
• Impulses are sent as electrochemical signals
• Organs include: Brain & Spinal cord (Central NS)
Nerves or neurons (Peripheral NS)
• Three general functions:
-sensory
-integration
-motor
Three General Function of the
Nervous System
A Typical Neuron Cell
Nervous Tissue
Basic Structure of a Typical Neuron
• Cell body- contains the genetic information & organelles
•
•
•
•
•
•
•
Axon- nerve fiber, conducts impulse away from cell body
Myelin sheath- lipoproteins surrounds the axon
Nodes of Ranvier- gaps in the myelin sheath
Dendrites – nerve fibers that are receptive surfaces
Schwann cells- neuroglial cells compose the sheath
Nissl bodies –membranous sacs (rough ER)
Neurofibrils –proteins that support the tissue
Cross Section of the Axon
Gray vs. White Matter
White matter: Nerve cells that are myelinated
-appears white in brain & spinal cord
-myelin produced by oligodendrocytes
-lack neurolemmal sheaths
Gray Matter: Nerve cells that are unmyelinated
-appears gray in the brain & spinal cord
-composes most of the CNS tissue
**Note: Myelinated cells more common in the peripheral
nervous system produced by schwann cells
Read the Article and answer the following questions:
1) What does the book “Driving Mr. Albert” tell about?
2) What did Marian C. Diamond discover about Einstein’s
brain?
3) What is the traditional thought of what glial cells do?
What is the new view in this article suggesting?
4) How are the voltage-sensitive ion channels different in a
glial cell vs. a typical neuron?
5) How do glial cells convey messages to other neurons?
6) Why are glial cells thought to be able to respond to a
range of chemicals?
7) What new laboratory method did scientists devise in order
to determine if glial cells (schwann cells) were sensitive to
neuronal signals?
8) How do glial cells and neurons work together? (pg. 57)
9) What did Peter Guthrie discover about astrocytes an ATP
in 1999? (pg. 58)
Article Questions
Read the Article “The Other Half of the Brain” and answer the
following questions:
•
What does the book “Driving Mr. Albert” tell about?
•
What did Marian C. Diamond discover about Einstein’s brain?
•
What is the traditional thought of what glial cells do? What is the
new view in this article suggesting?
•
How are the voltage-sensitive ion channels different in a glial cell
vs. a typical neuron?
•
How do glial cells convey messages to other neurons?
•
Why are glial cells thought to be able to respond to a range of
chemicals?
•
What new laboratory method did scientists devise in order to
determine if glial cells (schwann cells) were sensitive to neuronal
signals?
•
How do glial cells and neurons work together? (pg. 57)
•
What did Peter Guthrie discover about astrocytes an ATP in 1999?
(pg. 58)
Neuroglial cells (glial cells)
• Found in the Central Nervous System
• Fill spaces
• Provides scaffolding
• Guides & stimulates specialization
• Produces growth factors
• Nourishes other neurons
• Removes ions and neurotransmitters that accumulate
• Four different Types:
Astrocytes Oligodendrocytes Microglial Ependyma
Neuroglial Cells
Classifying Neurons
•
•
•
•
Size (length)
Shape:
Bipolar, Unipolar, Multipolar
Function: Sensory, Interneuron, Motor
Number of Synaptic knobs
Structural Differences of Neurons
• Bipolar neurons: eyes, ears, and nose (sensory)
• Unipolar neurons: (ganglia outside the CNS)
• Multipolar neurons: (brain & spinal cord)
Structural Types of Neurons
Functional Differences in Neurons
Sensory neurons
-receptor ends
-controls impulses toward the CNS
-referred to as afferent neurons
Interneurons
-association nerves
-multipolar neurons, CNS
Motor neurons
-Efferent nerve fibers
-controls impulses away from the CNS
-common in glands and muscle tissue
The Four Types of Neuroglial Cells
• Astrocytes~ star shaped cells
-found between neurons and blood vessels
-provides support & binds structures together
-regulated glucose and potassium concentrations
-responds to brain injury
-nourishes nearby neurons & releases growth factors
• Oligodendrocytes
-arranged in rows
-forms the myelin sheath around the axons (in CNS)
-produces nerve growth factors
• Microglial Cells
-scattered
throughout the CNS
-provides structural support
-Phagocytic (immune protection)
• Ependymal
-cuboidal /columnar cells
-lines the ventricles (cavities) of the brain
-allows free diffusion of CSF (cerebral spinal fluid)
Table-Pg. 366
Neuroglial Cells
Migraine Headaches (pg. 358)
• A response to changes in the diameters of the blood
vessels in the brain
• Constriction followed by dilation
• Symptoms: pain, vomiting, sensitivity to light
• Classical (4-6 hrs) observed in 10-15% sufferes
• Common migraines: lasts up to 3 to 4 days
• Serotonin levels are abnormal (constrict vessels)-deficiency
• Some think caused by diet: chocolate, wine, nuts, etc.
• Beta blockers (imitrex & tricyclic antidepressant)
keep the amount of serotonin available
Nerve Regeneration Pg. 362
• Can occur if the axon is damaged
• Will not occur if the cell body is damaged or separated from
the axon
• In peripheral nerves
-the proximal ends can regenerate (must be guided)
-distal portion will degenerate if damaged
-proximal end of injury regenerate with help from the
Schwann cells which will proliferate.
• In the CNS regeneration is highly unlikely
• Growth rate: 3 to 4 mm per day
• Neuromas can develop when the injury gap is more than
3mm.
A Typical Neuron Cell
Cross Section of the Axon
Impulses Conducted through Neurons
Florescent Image of two Neurons
The Axon of a Neuron
An Animated View
• Voltage gated channels & Proteins:
http://highered.mcgrawhill.com/sites/0072437316/student_view0/chap
ter45/animations.html#
**Choose the “sodium-potassium exchange” clip
Introductory Questions #2
1)
2)
3)
4)
5)
6)
How are motor neurons different from sensory neurons? How are
neuroglial cells different from typical nerve cells? Name all four
types of neuroglial cells and indicate the one that provides immune
protection.
What is the name of the small spaces that exist between the
neurons? Can you give an example of a chemical that can be found
in this space?
How does the cell membrane become polarized in a neuron?
What are the major ions associated with generating a membrane
potential? Which ions are present in large amounts inside and
outside the cell? What causes the inside of the cell to be more
negative (less positive) compared with the outside? How much of a
difference is there?
How is the resting potential different from an action potential?
What does it mean when a membrane is “Depolarized” and
“Repolarized”?
A Look at the Membrane Proteins
Factors that lead to a Resting Potential
• A charge difference builds across the membrane
• It becomes Electrically charged (polarized)
• Unequal distribution of ions one each side of the
membrane: K+ and Na + (cations)
• Inside is negatively charged vs.the outside
which is positively charged
• Involves pores and channels (proteins) that are
embedded within the membrane
Factors that Build a Polarized State
• Potassium ion move through the membrane more
easily than sodium
• High [Na+] on the outside & low on the inside
• High [K+] on the inside and low on the outside
• Anions are present inside the cell that cannot
diffuse through the membrane (impermeable)
(phosphates, sulfates, and proteins)
• Potassium ions can diffuse out faster than sodium
ions can diffuse in
Animated view:
http://bcs.whfreeman.com/thelifewire/content/chp44/4401s.swf
The Sodium-Potassium Pump:
Establishing a Resting Potential
Neural Signaling
Resting Potential & Action Potential
• Resting Potential:
–
–
–
–
–
–
Cell reaches a charge difference of –70mV
More Cations (Na+ & K+) on the outside
More anions inside and very little Na+ & K+
K+ is diffusing out (high to low)
Na+ can’t diffuse in so remains high outside
Sodium/potassium pump increases this difference
• Action Potential:
– A depolarization & repolarization occurs
– Speed is one-one millionth of a second
Neural Signaling
Threshold potential: Must reach
The action potential involves: Depolarization & Repolarization
Voltage-gated ion channels open & close (Na+& K+)
1-Resting state: both channels closed Membrane potential (-70mV)
2-Threshold is reached (-50 to -55 mV) caused by a stimulus
- Na+ channels open and sodium rushes in the cell
3-Depolarization action potential is generated as Na+ moves in cell
-cell internally becomes more positive: -40mV----20mV---etc
***A peak is reached of about +35 mV
4-Repolarization- begins once the peak voltage of +35mV is reached
-Na+ channels close
-K+ channels open and potassium ions leave the cell
-The cell internally becomes negative
5-Undershoot –80mV to –90mV is reached for a brief time
-Both gates close
-K+ channel is slow to close & resting potential is restored
Introductory Questions #3
1)
2)
3)
4)
5)
6)
7)
8)
After reading Clinical application 10.1 (pg. 358), how does a
migraine headache occur? What can be done to relieve the
pain?
How does gray matter different from white matter (other than
color)?
Is it possible for a neuron to regenerate? If so, explain how.
How does the cell membrane of a neuron become polarized?
What are the major ions associated with with generating a
membrane potential?
Explain what a threshold potential is and give the voltage value
that must be reached by the neuron’s membrane.
What happens during the refractory period?
What is the peak voltage for the action potential?
Explain what is happening when “hyperpolarization” occurs.
How is hyperpolarization different from Depolarization?
Key Steps of an Action Potential
An Action Potential
• Voltage gated channels & Proteins:
http://highered.mcgrawhill.com/sites/0072437316/student_view0/c
hapter45/animations.html#
Choose: “Action potential propagation in an
unmyelinated axon”
Beginning of an Action Potential
Self-Propagating Signaling
•
•
•
•
•
•
The impulse travels as a “wave of Depolarization”
The action potential Regenerates itself after refractory period
Forward direction only
Action potential speed:
1-Axon diameter (larger = faster; 100m/sec)
2-Nodes of Ranvier (concentration of ion channels); saltatory conduction;
150m/sec
Homework Fri. 4/20
• Do the Practice STAR Test for Biology on my website.
(90 questions)
• Continue work on your Study Outline
– Do Pgs. 10-3 & 10-4
Homework Fri. 4/20
• Go to my website and do the Practice STAR Test for
Biology. (there are 90 questions)
• Write your answers on a separate sheet of paper.
• Bring it in on Monday, Receive a stamp, and you will be
able to grade it.
• After grading it, then you will able to attempt another 15
Question test and for every THREE questions you get
correct you will earn an extra credit point for a total or
possible of 5 points.
• Overall you can earn:
5 pts.
+
2 pts. +
1 pt.
= 8 pts.
(# correct)
(stamp)
(grading it)
Generating an Action Potential
Neural Signaling
• Excitable cells~ cells that can change membrane potentials
(neurons, muscle)
• Resting potential~ the unexcited state of excitable cells
• Gated ion channels (open/close response to
stimuli)photoreceptors; vibrations in air (sound receptors);
chemical (neurotransmitters) & voltage (membrane
potential changes)
• Graded Potentials (depend on strength of stimulus):
• 1- Hyperpolarization (outflow of K+) increase in
electrical gradient; cell becomes more negative
• 2- Depolarization (inflow of Na+) reduction in electrical
gradient; cell becomes less negative
Key Steps of an Action Potential
Depolarized & Repolarized
Membrane Activity
Membrane Proteins Role
Synaptic Cleft-Release of
Neurotransmitters
Homework (Thurs. 4/19)
• Read Pgs. 356 – 360 in Chapter
• Do more of the Study Outline for Chapter 10
http://highered.mcgraw-hill.com/sites/0072919329/student_view0/
• Do Pgs. 10-3 & 10-4
Multiple Synapses: IPSP & EPSP
Neurotransmitters
**There are thirty different types of Neurotranmistters
Acetylcholine (most common) “cholinergic”
•skeletal muscle
Biogenic amines (derived from amino acids)
•norepinephrine
•dopamine
•serotonin
Amino acids
•GABA (gamma-aminobutyric acid)
Neuropeptides
•endorphins
How Drugs affect Neurotransmitter activity
• Block the binding site for the neurotransmitter
• Reduce the effect of the enzyme that breaks down the
neurotransmitter
• Enhance the activity of the neurotransmitter
Drugs include:
-Nicotine (mimics activity)
-Curare (blocks the action acetylcholine)
Inhibitory
-Cannabis
-Alcohol
-Benzodiazepines
Causes Adrenalin release:
-Amphetamines
-Caffeine -Cocaine
Neurotransmitters affected by a Drug
•
•
•
•
Acetylcholine:
Serotonin:
Norepinephrine:
GABA:
Curare () & Nicotine ()
Prozac () & Tryptophan ()
Cocaine & Antidepressants
Valium
Read pg. 379-Clinical Application 10.5
What causes people to become addicted
to drugs?
Disorders with Neurotransmitters
Look at the tables listed on pg 377 and name the condition
and neurotransmitter that causes each condition.
-Excessive sleeping
-Inappropriate emotional responses, hallucinations
-Progressive muscular weakness (also pg. 373)
-Inability to sleep
-Memory loss, depression, and disorientation
-Tremor in the hands, slow movement from rigid muscles
-Uncontrollable movements of facial muscles
Simple Nerve Circuit
• Sensory neuron: convey information to spinal cord
• Interneurons: information integration
• Motor neurons: convey signals to effector cell (muscle or
gland)
• Reflex: simple response; sensory to motor neurons
• Ganglion (ganglia): cluster of nerve cell bodies in the
PNS
• Supporting cells/glia: nonconductiong cell that provides
support, insulation, and protection
Simple Nerve Circuit
Reflex- the Neurons involved
Sensory-Interneuron-Motor Neurons
Assignment Packet
•
•
•
•
•
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Study Guide (3 stamps)
Video notes (2 segments-20 statements)
Online quiz answers (one quiz only)
Practice (review) test ----today’s assign.
IQ’s #1-5
Notes taken in class
Introductory Questions #4
1) When a nerve cell is depolarizing what is happening in
regards to the sodium and potassium protein channels?
Is the potential becoming more positive or negative?
2) When an action potential arrives at the synapse, what
happens to the neurons permeability enabling the
exocytosis of neurotransmitters? Name three types of
neurotransmitters. Which is the most common
neurotransmitter?
3) From the video, which neurotransmitter was morphine
similar to? What happens to a neurotransmitter once it
has depolarized the postsynaptic membrane of the next
cell?
Introductory Questions #5
1) Name the neurotransmitter that effects sleep.
2) Name three drugs that have an effect on the
norepinephrine neurotransmitter (pg. 373) Name
the neurotransmitter that cannot be retaken up
and is blocked by Prozac .
3) How is an IPSP different from an EPSP?
4) How is a general visceral efferent nerve fiber
different from an special visceral efferent fiber?
5) Name three different reflex behaviors. Name the
five parts of a reflex arc. (See pg. 380, chart
10.7)