UNIT 2, PACKET 3: THE ORGANIZATION OF THE NERVOUS SYSTEM
AND THE MOLECULAR BASIS OF NEURAL TISSUE
I like nonsense, it wakes up the brain cells. Fantasy is a necessary ingredient in living, it's a way of looking
at life through the wrong end of a telescope. Which is what I do, and that enables you to laugh at life's
realities. Dr. Seuss
OBJECTIVES:
 Describe the anatomical and functional divisions of the nervous system
 Learn to draw and label the structure of a typical neuron and know what each
part does
 Learn the names and functions of neuroglia (honor- all 6; regular credit- 4)
 Explain how resting potential is maintained and why that is important
 Learn what happens when an action potential is generated
 Describe the synapse and what happens when an action potential reaches a
synapse
 Know some of the neurotransmitters and how they are excitatory or
inhibitory (we’ll decide which NT to know later)
 Know how various diseases/disorders/toxins affect the NS- rabies, brain
tumors, MS, puffer fish venom, diptheria
THIS PACKET BELONGS TO _______________________________________________.
IF YOU HAVE FOUND IT, PLEASE RETURN TO ROOM 345 OR THE
BHS SCIENCE OFFICE, ROOM 365.
LECTURE NOTES: THE NERVOUS SYSTEM, PART I
What do YOU think is the MAIN FUNCTION of the Nervous System?
ORGANS AND TISSUES
STRUCTURAL ORGANIZATION
3 MAJOR FUNCTIONS:
HISTOLOGY: TWO MAIN TYPES OF CELLS IN THE NS
NEUROGLIA HAVE A (MOSTLY) SUPPORTIVE ROLE
NEURON ANATOMY-structure vs function
NERVES ARE….
GRAY MATTER VS WHITE MATTER
READING GUIDE: CHAPTER 12
Write the chapter title here: ___________________________________________
Write the headings for Sections 12-1 through 12-6.
Section 12- 1 ___________________________________________________________
Section 12- 2 ___________________________________________________________
Section 12- 3 ___________________________________________________________
Section 12- 4 ___________________________________________________________
Section 12- 5 ___________________________________________________________
Section 12- 6 ___________________________________________________________
Label the diagram below. See Figure 12-1, p. 388.
Section 12-1 The nervous system has anatomical and functional divisions
The Anatomical Divisions of the Nervous System
1. What are the two main anatomical divisions of the nervous system?
The Functional Divisions of the Nervous System
1. The Peripheral Nervous System is divided into two divisions: the _________________ and the
______________________.
2. What are receptors? Give examples.
3. What does afferent mean?
4. What does efferent mean?
5. There are two main divisions of the nervous system: Central and Peripheral. What are the
two main divisions of the Peripheral Nervous System?
6. Draw a concept map (without looking at the answers) illustrating the divisions of the
Nervous System below using: Central, Peripheral, Brain, Spinal Cord, Somatic, Autonomic,
Voluntary, Involuntary, Parasympathetic, Sympathetic
NERVOUS SYSTEM
Section 12-2 Neurons are nerve cells specialized for intercellular communication
The Cell Body
1. What is the function of the cell body?
2. Why are neurons generally unable to divide by mitosis?
Dendrites and Axons
1. What is the function of the dendrites?
2. What is the function of the axon?
The Synapse
Label the diagram below using the following: mitochondrion, presynaptic membrane,
synaptic vesicles (aka neurotransmitters), synaptic cleft, post-synaptic membrane (of
next neuron)
1.What happens at the synapse?
Read the Clinical Note Rabies
1. How does the rabies virus travel from the site of the bite to the brain?
The Classification of Neurons
Optional: Structural Classification of Neurons
Functional Classification of Neurons
Sensory Neurons
1. What do sensory neurons do and where are they found?
Motor Neurons
1. What do motor neurons do?
Section 12-3 CNS and PNS neuroglia support and protect neurons
Label the diagram below. See Figure 12-4, p. 393. Try to condense the information into your
own words.
1.
1. What is the blood brain barrier? Why is it important? When might it be problematic?
Read the Clinical Note TUMORS
1. What types of cells in the nervous system are responsible for tumors in adults?
2. What types of cells can give rise to tumors in young children under the age of 4? Why are
those cells involved in brain tumors?
Neuroglia of the Peripheral Nervous System
Label the diagram below using the following terms: myelinated internode, nodes, axon,
nucleus, dendrite. See Figure 12-6 on p. 395.
2. What is the advantage of myelination?
Read the Clinical Note DEMYELINATION, p. 397
1. What is demyelination and what is the result?
2. What can cause demyelination?
3. What is diptheria?
4. What is Multiple Sclerosis?
5. What is Guillain-Barre Syndrome?
Neural Responses to Injury, p. 397
1. The key to recovery for neurons is in the part of the neuron called the _____________.
2. Pressure on the damaged axon that is alleviated (removed) within a few hours can lead to
recovery within a few weeks. Can a neuron recover if the pressure is severe or prolonged?
3. HONOR credit: Describe how Schwann cells in the PNS help the injured neurons recover
(See Fig. 12-7). When is it not successful?
Section 12-4. The transmembrane potential is the electrical potential of the cell’s
interior relative to its surroundings.
1. All cells have a transmembrane potential. What is the transmembrane potential?
Below is a description in a nutshell of how neurons communicate with one another. Read
the red bullets on p. 399 to follow along.
a. A stimulus produces a temporary change in the electrical potential of the neuron
membrane. It is called a graded potential because it ________________________.
b. If the graded potential is large enough, it triggers an ______________________.
The action potential is the change in membrane potential along the axon. It does NOT
diminish as it moves towards the opposite end of the neuron.
c. When the action potential reaches the terminal end of the neuron it produces a
________________ potential in the postsynaptic cell, usually be releasing a neurotransmitter.
d. The response of the postsynaptic cell depends on what the stimulated receptors do and
what other stimuli are present. The integration of all the stimuli at this point is the simplest
form of ______________________________ in the nervous system.
The Transmembrane Potential
Three Important Concepts to understand about the Transmembrane Potential
1. The ECF- fluid outside the neuron- is high in ____________ and ___________, whereas the
cytosol (inside the cell) is high in _______________ and ____________.
2. The neuron membrane is ________________ _______________________, though membranes have
___________ channels. Active transport also moves specific ions _____ or ________ of the cell.
3. Passive and active transport mechanisms do not mean that there will be an equal
distribution of ions on either side of the membrane. Why not?
Passive Forces acting across the Plasma Membrane
1. Passive forces are due to both ________________ and ___________________ gradients.
2. What is a chemical gradient?
3. What is the electrical gradient?
4. (choose negative or positive to fill in the blanks) Overall, a neuron is ________________
INSIDE and ________________________OUTSIDE.
See Tips and Tricks on p.401.
5. Describe the Electrochemical Gradient in a nutshell.
6. Given that K+ concentrations are higher inside the cell than outside, why doesn’t K+ move
out of the cell in higher numbers?
7. Given that Na+ concentration is higher outside than inside the cell, why doesn’t more Na+
move into the cell when the neuron is at rest?
8. Since some K+ leaks out of the cell and a little Na+ manages to move into the cell, how
does the cell maintain a difference in electrical charge and concentration of K+ and Na+ ?
(see Active Forces across the Membrane: The Sodium and Potassium Pump)
***Skip to p. 409 and read the Summary Table 12-3 Generation of an Action Potential
Write what is happening at each stage in the process.
Section 12-8 Write the title here: __________________________________________
1. The nervous system produces a number of neurotransmitters, some that are USUALLY
excitatory and others that are USUALLY inhibitory. Why do they say USUALLY?
2. HONOR CREDIT: (optional for Regular credit)What is a neuromodulator? Give an
example. Briefly describe the 3 ways that neuromodulators work. Use the table below. Info
is on p. 418.
How Neuromodulators
work
Direct Effects
Indirect via G Proteins
Indirect via Enzymes
3. Define the following neurotransmitters- whether they are USUALLY excitatory or
inhibitory or equally excitatory and inhibitory, and where they typically act. SEE P. 420-421
TO COMPLETE THE TABLE
NEUROTRANSMITTER/
MODULATOR
Acetylcholine
Norepinephrine
Dopamine
Serotonin
GABA
Substance P
Endorphins
Anandamide
WHERE IT ACTS
EXCITATORY
INHIBITORY
THE FROZEN ADDICT video, aka Brain Transplant
1. The illicit chemist who tried to produce a synthetic version of heroin actually
produced a dangerous drug. What was his/her mistake and what was the drug
called?
2. What part of the brain was affected in the people who took the bad form of synthetic
heroin? Which neurotransmitter was involved?
3. What were the symptoms of the patients? What disease did this resemble?
4. Explain briefly the surgery performed on two of theses patients. Why was it
controversial?
IN CLASS: Online Tutorial for The Nervous System: Neuroscience: Addiction and
Genetics of the Brain.
Go to http://learn.genetics.utah.edu or Google Learn.genetics.utah and go to the
home page. Scroll down to Neuroscience: Addiction and Genetics of the Brain.
I.
Watch The Brain’s Reward Pathways and do the short tutorials in that section.
II.
Scroll down to Addiction and Genes.
Read Genes and Addiction, the first segment.
1) Why can scientists use animals as models for the study of
addiction?
2) How many genes have scientists identified (at the time of this
tutorial was made) that play a role in addiction? What implication(s) might that have in
treating addiction?
III. Read Animal Models and Addiction
Mouse Models for Addiction
1) What was the first clue that addiction might have a genetic component when
using animals in addiction studies?
The Reward Pathway is Fundamental
2) What makes animals as susceptible to addiction as humans?
Of Mice and Men: How Similar are We?
3) Mice and humans have the same reward pathway and similar genes, so what
makes us so different?
Animal Models and Gene Discovery
4) How are animal models useful to studying addiction?
5) How do you feel about the use of animal models in studying addiction?
IV. Go to Challenges and Issues.
1) Start at Changing Attitudes at the top of the page and read/listen to the
segment about addiction as a brain disease.
2) Optional: Read Culture Use of Drugs. Should certain religious or cultural
groups be permitted to use an illegal drug? If so, how should that use be
regulated?
3) Optional: Prescribing Drugs of Abuse. Do you think clinical trials on
drugs like ecstasy and marijuana send the message that recreational
use of the drug is OK?
4) Optional: Genetic Profiles for Addiction.
Should knowing that there is a genetic susceptibility to addiction
change how society views and treats addiction? What about the addicts
themselves?
5) CHOOSE either Cannabis in the Clinic- The Medical Marijuana Debate OR
Ritalin and Cocaine.
a.) If you choose Cannabis in the Clinic- read and listen to the
segment for the second segment on The Endocannabinoid Receptor.
What is the endocannabinoid system and what does it do for us?
b. ) If you choose Ritalin and Cocaine: The Connection and the
Controversy, answer the following questions.
i) When was Ritalin first prescribed and who are the majority of
patients to whom it is prescribed?
ii) Describe how Ritalin is similar to cocaine at the molecular level.
iii) What do you think about the consequences of misdiagnosis of
ADHD?
V. Choose either Mouse Party or Meth Mouse (Which might not work-if it doesn’t go
to the next segment if you have already done Mouse Party). See separate handout.
A. Mouse Party. Choose 4 mice (drugs) to study what happens in the nervous
system and complete the chart below.
Drug
1.
2.
How Does it Interact with
receptors?
What are the dangers of this
drug?
3.
4.
Explain why specific drugs have the side effect(s) they have.
B. If you choose Meth Mouse- draw and label the parts of the synapse and
describe what is happening at each part.
VI. How Drug Use Affects the Brain Over Time- summarize in a few sentences in the
space below!
VII. Beyond the Reward Pathway- you can skim through most of this, but read and
summarize the part about Serotonin.
VIII. Go to How Drugs Can Kill and answer the following questions.
1. What is a Polydrug cocktail? Why can drugs in combination be lethal? Name the system(s)
involved and specific organs.
2. Describe how heroin can be lethal. Be specific. Name the system(s) involved and specific
organs.
3. Describe 2 ways that alcohol overdoses can be lethal. Name the system(s) involved and
specific organs.
4. How can people overdose on nicotine? What happens to a person who overdoses on
nicotine? Name the system(s) involved and specific organs.
5. How do stimulants cause death? Name the system(s) involved and specific organs. Give
two examples of stimulants
HOMEWORK: Read the article below and answer the following questions:
1. What was the drug he took that caused his symptoms?
2. Describe his symptoms.
3. What is pancreatitis and how did this drug cause pancreatitis?
Toxic Toking, By LISA SANDERS, M.D. MARCH 14, 2014
The Presenting Problem. For a young man, nausea is just the beginning.
Sweating it Out
“Dad, I’ve got to go to the hospital,” the young man croaked in a near whisper, which his father
barely heard over the hum of the traffic outside the car. “I’m sick again.” The middle-aged man
glanced over at his 25-year-old son. His face was drained of color and shiny with sweat despite
the frigid winter day.
He took the next exit and headed toward Waterbury Hospital, in Waterbury, Conn.
The young man woke early that morning with the familiar feeling of weight in his stomach that
always preceded an attack of vomiting. He forced himself out of bed and did a few quick pushups. His mouth flooded with the taste of bile — a hint of what was to come. If he could just take
his anti-nausea medication and get into a hot shower, he might still be able to fight it off. He
worked with his father in his contracting business, and he hated disappointing him.
Kicking a Bad Habit After he got out of the shower, he felt much better. On the way to work, his
father drove him to the methadone center, where he received the daily dose that kept him from
relapsing into his heroin habit. But, standing in line, waiting for the little cup of red liquid, the
heaviness again settled in his stomach. He gulped the medicine and hurried back to the car.
He sat with his eyes closed as his father drove. Suddenly he was ice-cold; sweat streamed from
every pore; acid burned deep in his throat. He knew he couldn’t work. Maybe he could make it to
the hospital before he started vomiting. He knew from experience that once he got started, he
wouldn’t stop for hours.
When the young man arrived at the E.R., he was drenched. In a small room, he pulled on a
hospital gown and lay down next to a large pink basin to wait for the inevitable paroxysms to
start. By the time a doctor came in, the patient had been vomiting for a while and had nothing left
in his system. He told the doctor that he got these episodes of nausea fairly regularly — maybe a
couple of times a month. Sometimes he could tough it out. But far too often, he ended up either
here or at the hospital across town.
Inflammation The young man looked tired and uncomfortable. His skin and lips were pale and
dry. His blood pressure was high, and his belly was a little tender. The doctor wasn’t surprised.
The results from the blood sample drawn earlier showed elevated levels of pancreatic enzymes,
which suggested that his pancreas was inflamed — a condition known as pancreatitis. The
pancreas makes the chemicals that break down food in the small intestines. But certain
medications, diseases or alcohol can occasionally cause those chemicals, so beneficial in the
digestion of food in the intestine, to be released inside the pancreas itself, causing the breakdown
of the delicate tissues of that organ. The result is nausea, vomiting and extreme abdominal pain.
All doctors can do at that point is to treat the pain and keep the patient from becoming dehydrated
from all the vomiting.
Dr. Virginia Brady, the resident on call that day, hurried down to the E.R. after hearing about the
young man being admitted with pancreatitis. When she entered his room, he was asleep, a slender
tattooed arm slung across his face. He awakened quickly and, after wiping the sweat from his
face, recounted the day’s on-again, off-again nausea and vomiting. It was frustrating, he told the
young doctor, because he used to think his nausea was caused by alcohol — but he gave that up
five years ago. Then he blamed drugs: heroin, cocaine, marijuana — he did them all. But a few
months earlier he gave them up too. And the methadone program made sure he stayed clean, he
added. But he was still getting sick just as often.
Other Drugs Brady asked whether he took any drugs at all. The man reported that he took an
antidepressant, an antihistamine to help him when he had trouble sleeping and a nausea pill that
he was prescribed when this started about eight years earlier. And, he added reluctantly, there was
this stuff sold under the name Spice — a so-called synthetic marijuana — that he smoked daily.
But it was mostly just a bunch of dried weeds, which he bought at a little neighborhood store. It
definitely wasn’t marijuana. Otherwise it would show up in the urine tests he had to take almost
every week.
On exam, his blood pressure had come down and his belly was soft and no longer tender. His
bowel sounds were quieter than normal but the rest of his exam was unremarkable.
Brady wondered what had made this young man so sick. The nausea, vomiting and elevated
pancreatic enzymes certainly suggested pancreatitis. But an ultrasound of his belly showed a
normal pancreas. Moreover, patients with pancreatitis usually have excruciating abdominal pain,
and this man had none.
Was there something about Spice that could affect enzymes in such a way to suggest pancreatitis
but without the abdominal pain? Brady wasn’t sure. But the nausea the patient described —
starting in the early hours of the morning, causing unremitting vomiting that got better with a hot
shower — sounded like a syndrome she had seen in patients who smoked pot nearly every day.
Why marijuana, a drug sometimes used to fight nausea, should in some people produce
cannabinoid hyperemesis (as the pot smoker’s vomiting syndrome was called) is not clear.
Cannabinoids have been shown to slow down the gut. One theory is that too much cannabinoid in
the system slows it down too much, leading to nausea and vomiting. Oddly, virtually all the
people who experience the nausea feel much better while they are taking a hot shower. Somehow
the water — as hot as they can stand it — makes the nausea disappear. It was the defining quality
of the syndrome, described by a physician in South Australia in 2004, who noted that several
patients with so-called psychogenic vomiting would get better just by being in the hospital, where
they couldn’t smoke marijuana, and taking very hot showers. All were heavy marijuana users.
The users who smoked again once more experienced the symptoms.