Download The Nervous system

The Nervous system
The nerve cell is the basic unit of communication in the
vertebrate nervous system
Components of the Nervous
System
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Figure 11.1
Three Classes of neurons
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The Neural circuit consists of
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Sensory neurons
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Interneuron (CNS)
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receptor for stimulus
integrate signals
Motor neuron
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transfer signal to effector (muscle)
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Types of Neurons in the
Nervous System
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Figure 11.2
Anatomy of a Neuron
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Cell body: functional
portion
Dendrites: short
extensions that receive
signals
Axon: long extension that
transmits impulses
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How does a neuron hold and
move info?
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A neuron at rest has a voltage difference
across the plasma membrane called a
resting voltage potential
An action potential (AP) is when this charge
across the membrane is briefly switched
The action potential moves down the
membrane at a rapid pace.
Ap can move faster over mylenated portions
is called saltatory conduction
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Myelinated Neuron
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Figure 11.7a
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Maintenance of the Resting
Membrane Potential
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Figure 11.3
Resting Membrane Potential,
Graded Potentials, and an
Action Potential
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Figure 11.4
The Nerve Impulse Is a
Bioelectrical Signal
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The sodium-potassium pump uses ATP to transport sodium ions out
and potassium ions in
The inside of a resting neuron has a negative charge relative to the
outside
An action potential is a reversal and restoration of the charge
difference across the membrane
The sodium-potassium pump restores the original distribution of ions
Action potentials are all-or-none events
A neuron cannot fire during the refractory period
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How does a signal move
from one neuron to another?
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A synaptic cleft divides 2 neurons
The AP will not move across the synaptic cleft
Neuro transmitters are released by the signal
cell to the receiver cell
Move by diffusion
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Transfer of Information from
Neuron to Target
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Synaptic transmission:
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Release of neurotransmitter: graded potential achieved
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Effects of neurotransmitter:
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Excitatory: depolarize postsynaptic cell
Inhibitory: hyperpolarize postsynaptic cell
Role of postsynaptic neuron: integrate and process
information
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Types of chemical synapse
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Acetylcholine: neuromuscular junctions,
glands, brain and spinal cord
Norepinepherine: affects brain regions
concerned with emotions, dreaming
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From table 11.1
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The nervous System
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Paths of information flow
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Signals between the
brain and spinal cord
move to the body
regions by nerves
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Sensory nerves move a
signal towards the brain
and spinal cord
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Motor neurons move a
signal from the brain or
spinal cord to the body
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Divisions of the nervous
System
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Central nervous system
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CNS
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Is the brain and spinal
cord
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Peripheral nervous
system
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PNS
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all nerves that carry
signals to and from the
CNS
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Parts of the PNS
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Sensory Division carries info to the brain
and spinal cord.
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Motor Division carries info from the brain to
the bodies effectors (things that do the work)
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The Motor division of the
PNS has 2 divisions
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Somatic nerves relay
commands to and from
skeletal muscle
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Autonomic nerves
send signals to and
from smooth muscles
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Voluntary control
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Involuntary control
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Sympathetic
Parasympathetic
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The autonomic divisions
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Parasympathetic
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Sympathetic
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slow down the body
activity when the body
is not under stress
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Rest and digest
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increase overall body
activity during times of
stress, excitement or
danger
fight or flight
response
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hormone epinephrine
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Fig 11.12
Sympathetic and
Parasympathetic
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Are Antagonistic
Work towards the automatic, subconscious
maintenance of homeostasis.
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Parts of CNS
Components of the CNS
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Spinal cord
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31 pair of spinal nerves
Grey matter
White matter
Controls some reflex
actions like bladder
emptying
Brain parts
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Hindbrain
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Midbrain
Forebrain
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medulla oblongata
cerebellum
pons
cerebrum
thalamus
hypothalamus
Ventricles of the Brain and
Circulation of Cerebrospinal
Fluid
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Figure 11.13
Brain: Major Divisions
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Hindbrain: coordinates basic, automatic, vital
functions
Medulla oblongata: controls automatic functions
of internal organs
Cerebellum: coordinates basic movements
Pons: aids flow of information
Midbrain: coordinates muscles related to vision
and hearing
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Brain: Processes and Acts
on Information
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Forebrain: receives and integrates information concerning
emotions and conscious thought
Hypothalamus: helps regulate homeostasis
Thalamus: receiving, processing, and transfer center
Limbic system: neuronal pathways involved in emotions
and memory
Cerebrum/cerebral cortex: higher functions
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Sleep
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Sleep center: reticular activating system
(RAS)
Stages: based on electroencephalograms
(EEGs):
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Stage 1: transitional, random small waves on EEG
Stage 2: skeletal muscles relax, little eye or body
movement, EEG shows sleep spindles
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Sleep (cont.)
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Stage 3: heart and respiration slower, EEG shows slow
wave sleep
Stage 4: difficult to awaken, heart and respiration
slowest, body temperature decreased
REM (rapid eye movement) sleep: dreaming, EEG same
as awake
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Limbic System: Emotions of
Fear, Anger, Sorrow, Love
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Figure 11.19
Memory: Storing and
Retrieving Information
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Short term: working memory, information
from previous few hours
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Long term: information from previous days to
years
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Other parts of the CNS
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The two cerebral hemispheres communicate
through the corpus collosum
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left verbal skills
right nonverbal skills such as music math, abstract
Brain cavities and Canals
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cerebrospinal fluid surrounds and fills in cavities in the
brain
Blood Brain barrier- controls what moves into the brain.
Will prevent infections.
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Our state of consciousness
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The CNS governs sleeping, dozing,
daydreaming and full alertness
neurons of the reticular activating system
RAS control the changing levels of
consciousness by releasing serotonin.
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Memory
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Association is the
linkage of information
to structural and
chemical changes
short term- few bits
lasts a couple of hours
Long term- permanent
and limitless
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The most important info
goes rapidly into long
term storage
memory is stored in a
form resistant to
degradation
Possibly caused by
changes in synapses.
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Tips on studying
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Concentrate on what you study.
Minimize interference.
Study takes time.
Break material into smaller portions.
Rephrase materials in your own words.
Test yourself to see what you know.
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Primary somatosensory and
motor areas of cerebral
cortex
Disorders of the nervous
system
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Trauma
Infections
Transmission and synaptic defects.
Abnormal growth
Headache
Tumors
Stroke
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Psychoactive Drugs
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Action: affects higher brain functions
Psychological dependence: user craves the
feeling associated with the drug
Tolerance: takes more of the substance to
achieve the same affect
Addiction: the need to continue obtaining and
using a substance; no free choice
Withdrawal: physical symptoms that occur upon
stopping the drug
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Know what the parts of the
brain do
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Brain parts
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medulla oblongata
cerebellum
pons
cerebrum
thalamus
hypothalamus
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Bio 130 Human Biology
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seratonin
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Just a reminder to talk
about drugs that
interact with brain.
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