Transcript Regents Biology - Mrs. Pisciotta

AP Biology
The
Nervous
System
2003-2004
Overview
 The Nervous System controls and
coordinates all the functions of the
body.
 The Nervous System consists of two
main sub-divisions:


Central Nervous System (CNS)
Peripheral Nervous System (PNS)
• The Peripheral Nervous System is
divided into two sub-divisions:


Somatic- voluntary
Autonomic- involuntary
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http://inside.salve.edu/walsh/cns_pns.jpg
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Structure and Function of the Neuron
 Neuron is the scientific name for a Nerve
Cell.
 Neurons consist of 3 basic structures:



Cyton, or cell body.
Dendrites- receive messages, impulses, and
send them to the cell body.
Axons- send messages away from the cell
body.
• Nerve impulses travel from one neuron to
another across synapses, or spaces in
between the cells.
• The “jumping across” the synapse is
facilitated (helped) by chemicals called
Neurotransmitters.
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Parts of the Cell
 Dendrites – Branched
 A Neuron
parts of a neuron that
receive impulses from
other neurons.
 Cyton- Contains
cytoplasm and the
nucleus. Impulses pass
through here to the
axon.
 Axon- Single long fiber
that carries impulses
away from the cell body.
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Myelin coating
signal
direction
 Axon coated with insulation
made of myelin cells

speeds signal
 signal hops from node to node

330 mph vs. 11 mph
myelin coating
Multiple Sclerosis
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 immune system (T cells) attacks myelin coating
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 loss of signal
Synapse
Junction between nerve cells


1st cell releases chemical to trigger
next cell
where drugs affect nervous system
synapse
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Types of Neurons
Neurons can also be classified by the direction
that they send information:
･Sensory (or afferent) neurons: send
information from sensory receptors (e.g., in
skin, eyes, nose, tongue, ears) TOWARD the
central nervous system.
･Motor (or efferent) neurons: send information
AWAY from the central nervous system to
muscles or glands.
･Interneurons: send information BETWEEN
sensory neurons and motor neurons. Most
interneurons are located in the central
nervous system.
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Reflexes
 Stimulus- a change


in the environment.
Response/Reactionhow the body reacts
to a stimulus.
Reflex Arc- the
pathway that an
impulse follows to
illicit a response to a
stimulus.
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Central Nervous System
 Brain
 Spinal cord
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Protections
1. Skull and Vertebrae
2. 3 protective layers called meninges
3. Dura Mater (outer layer): consists of connective tissues,
blood vessels, and nerves.
4. Arachnoid Layer (middle layer): elastic and weblike
5. Pia Mater (inner layer): contains nerves and blood vessels.
6. Cerebrospinal fluid




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a clear watery liquid
separates the middle and inner layers
Acts as shock absorber
exchange of nutrients between blood and nervous system
The Brain




Coordinates body activities
Made up of approximately 100 billion neurons
Uses 20% of bodies oxygen and energy
Divided into three major parts


the Cerebrum
the Cerebellum
the Brain Stem (Medulla Oblongata, Pons)
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Cerebrum
 Largest part of the brain
 Thinking
 Memory is stored
 Movements are controlled
 Impulses from the senses are
interpreted.
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Cerebrum specialization
 Regions specialized for different functions
 Lobes

frontal
frontal
parietal
 speech,
control of emotions

temporal
 smell, hearing

occipital
 vision

parietal
 speech, taste
reading
temporal
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occipital
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Brain Tumor Surgery
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Sub-Arachnoid Cyst Removal
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Subdural Hematoma
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Gray Matter vs. White Matter
 Gray Matter – Absence of myelin in

masses of neurons accounts for the gray
matter of the brain – Cerebral Cortex
White Matter - Myelinated neurons gives
neurons a white appearance – inner layer
of cerebrum
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Cerebellum
 Responsible for the
coordination of
muscles and is the
center of balance
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Medulla
 Center of heart beat,
respiration, and
other involuntary
actions
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Other Structures inside the Brain
 Thalamus – receives messages from
sensory receptors; relays information to
proper regions of cerebrum
 Hypothalamus - Regulates hunger, thirst,
fatigue, anger, etc…

Control of pituitary for endocrine function
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Section 35-3
Cerebrum
Thalamus
Pineal
gland
Hypothalamus
Cerebellum
Pituitary gland
Pons
Medulla oblongata
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Spinal cord
The Spinal Cord
 Extension of the brain stem
 Bundles of neurons that carry impulses
from all parts of the body to the brain
and from the brain to all parts of your
body
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The
Peripheral
Nervous
System
Your brain
and spinal
Somatic
cord are
and
connected
Autonomic
to the rest
Systems
of your
The
body by
peripheral
the
nervous
peripheral
system
has
nervous
two
major
system.
divisions.
The PNS
is made up
somatic
of 12 pairs
system
of nerves
controls
from your
voluntary
brain It
actions.
called
is
made up
cranial
of
the
nerves, and
cranial
and 31
spinal
pairs from
nerves
that
your
go
from
spinal
the
cord called
central
spinal
nervous
nerves. to
system
Spinal
your
nerves are
skeletal
made up of
muscles.
bundles of
The
sensory
autonomic
and motor
system
neurons
controls
bound
involuntary
together by
actionsconnective
those
not
tissue. For
under
this
conscious
Research
reason,
controla
Visit the
single
such
as
Glencoe
spinal
your
heart
Science
nerve
rate,
can
Web site at
have
breathing,
tx.science.
impulses
digestion,
glencoe.co
going
and
to
m forfrom
more
and
glandular
information
the
functions.
brain at
about
the
the
These
same
two
nervous
time.
divisions,
Some
system.
nerves
along
with
Make
a
contain
the
central
brochure
only
nervous
outlining
sensory
system,
recentup
neurons,
make
medical
and
your
some
advances.
contain
body's
only motor
nervous
neurons,
system.
but most
nerves
contain
both types
of neurons.
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Peripheral Nervous System
 Connects body to brain & spinal cord
 12 pairs of nerves from your brain

(cranial nerves)
31 pairs from your spinal cord (spinal
nerves)

Bundles of sensory and motor neurons
held together by connective tissue
 Two divisions
Somatic
 Autonomic

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http://www.christopherreeve.org/Research/Research.cfm?ID=178&c=21
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Divisions of the PNS:
Somatic Nervous System
 Controls voluntary actions
 Made up of the cranial and spinal
nerves that go from the central nervous
system to your skeletal muscles
Autonomic Nervous System
 Controls involuntary actions-those not
under conscious control-such as your
heart rate, breathing, digestion, and
glandular functions
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Drugs and the Nervous System
 Drug – any substance, other than food
that changes the structure or function
of the body
 Legal
 Illegal
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Commonly Abused Drugs
Section 35-5
Drug Type
Medical Use
Examples
Effects on the body
Stimulants
Used to increase alertness,
relieve fatigue
Amphetamines
Increase heart and respiratory rates;
elevate blood pressure; dilate pupils;
decrease appetite
Depressants
Used to relieve anxiety,
irritability, tension
Barbiturates
Tranquilizers
Slow down the actions of the central
nervous system; small amounts cause
calmness and relaxation; larger
amounts cause slurred speech and
impaired judgement
Opiates
Used to relieve pain
Morphine
Codeine
Act as a depressant; cause
drowsiness, restlessness, nausea
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1. Stimulants
 Increase




Heart rate
Blood pressure
Breathing
Release of neurotransmitters at some
synapses in the brain
 Deplete neurotransmitters and lead to:




Fatigue
Circulatory problems
Hallucinations
Depression
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2. Depressants
 Decrease





Heart rate
Breathing rate
Blood pressure
Relax muscles
Relieve tension
 Enhances release of neurotransmitters
that prevent nerves cells from firing
 Alcohol with depressants can lead to
death – depresses CNS to a point one
stops breathing
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3. Opiates
 Mimics endorphins
 Endorphin – natural chemical in brain that
helps overcome pain
 When person stops taking



Brain has adjusted to high levels of
endorphins
Cannot produce enough natural endorphins
Suffer uncontrollable pain and sickness
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4. Cocaine





Sudden release of Dopamine
Powerful Stimulant
Increases heart rate and blood pressure
First time users can have heart attack
Dopamine – neurotransmitter in brain that is
released to give feeling of pleasure and
satisfaction
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5. Marijuana
 Active ingredient (THC) tetrahydrocannabinol
 More destructive to lungs than cigarettes

5 marijuana cigs = 120 conventional cigs
 Results in:


Lower WBC count by 40% - susceptible to infections
Teens –
 inhibits maturity
 Retards normal brain growth
 Memory loss
 Inability to concentrate
 Fall short on memory as well as math and verbal skills


Males – reduced testosterone levels and increases estrogen
levels
Females –
 disturbs menstrual cycle
 DNA damage to eggs
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More Effects (FYI)
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Impaired perception
Loss of coordination
Increased risk of accidents
Impaired judgement
Loss of motivation
Diminished inhibitions
Increased heart rate
Anxiety, panic attacks, and paranoia
Hallucinations
Damage to the respiratory, reproductive, and immune systems
Increased risk of CANCER
Psychological dependency
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6. Alcohol
 Depressant
 Slows down CNS



40% of 50,000 highway deaths are caused by
drinking and driving
1/3 of homocides attributed to effects of
alcohol
$150 billion dollars of U.S. economy alcohol
abuse treatment
 Fetal Alcohol Syndrome (FAS)


Drinking while pregnant
Heart defects, malformed faces, delayed
growth, poor motor development
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Alcohol and Disease
 Long-term alcohol use or bouts of
excessive consumption
Destroys liver cells
 Cirrhosis of liver – formation of scar
tissue that prevents blood flow through
liver

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Drug Abuse
 Intentional misuse of any drug for
nonmedical purposes
 Addiction – uncontrollable dependence
on a drug
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Only Way to Prevent Addiction
and Effects of Drugs
 NOT taking them to begin with
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Diseases, Conditions, and
Syndromes of the Nervous System
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Stroke
 Occurs when
there is not
enough oxygen
going to the
brain.
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Autism
Overview
Autism is a developmental disorder that appears in the first 3 years of life, and affects
the brain's normal development of social and communication skills.
Symptoms
Most parents of autistic children suspect that something is wrong by the time the child is
18 months old and seek help by the time the child is age 2. Children with autism typically
have difficulties in:
•Pretend play
•Social interactions
•Verbal and nonverbal communication
Some children with autism appear normal before age 1 or 2 and then suddenly "regress"
and lose language or social skills they had previously gained. This is called the
regressive type of autism.
People with autism may:
•Be overly sensitive in sight, hearing, touch, smell, or taste (for example, they may
refuse to wear "itchy" clothes and become distressed if they are forced to wear the
clothes)
•Have unusual distress when routines are changed
•Perform repeated body movements
•Show unusual attachments to objects
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Polio
 Viral disease of the central nervous
system that can cause paralysis.
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Meningitis
 Is an inflammation
of the membranes
that surround the
brain and spinal
cord.
 Disease is caused
by bacteria, or a
virus.
 Symptoms – Very
bad headache
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Cerebral Palsy
 Congenital
disease
 (born with)
 Disturbance of
motor functions
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Herniated Disk
 Disk in vertebra
moves up
against the
spinal nerves.
Very painful
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