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Chapter 49
Nervous System and Sense Organs
Table of Contents
Section 1 Neurons and Nerve Impulses
Section 2 Structure of the Nervous System
Section 3 Sensory Systems
Section 4 Drugs and the Nervous System
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Objectives
• Describe the structure of a neuron.
• Summarize the electrical and chemical conditions
that characterize a resting potential.
• Outline the electrical and chemical changes that
occur during an action potential.
• Explain the role of neurotransmitters in transmitting a
signal across a synapse.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Neuron Structure
• A neuron, or nerve cell, is made up of a cell body, dendrites,
and axons.
– A cell body is the nucleus of a neuron and most of its
organelles.
– Dendrites extend from the cell body and are covered by
a membrane.
– The axon is a long membrane-bound projection that
transmits information away from the cell body in the
form of electrical signals.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Structure of
a Neuron
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Parts of a Neuron
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Neuron Structure, continued
• The electrical signals that transmit information
away from the cell body are called action
potentials.
• The end of an axon is called an axon terminal.
• Axons are covered by a lipid layer called a myelin
sheath.
– The myelin sheath insulates the neuron which
speeds up the transmission of action
potentials along the axon.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Neuron Structure, continued
• The signaling activity of the nervous system is made up of
electrical activity within neurons and chemical flow
between neurons.
• Neurons communicate with each other at special junctions
called synapses.
• These synapses do not communicate by touch, but by
releasing chemicals, or neurotransmitters, into a gap
between the synapses called the synaptic cleft.
– The synaptic cleft is a small gap between the axon
terminal and the receiving cell.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Nerve Impulses
• A neuron, like all other cells, has a membrane potential.
– A membrane potential is a difference in the electrical
charge across a cell membrane.
• A membrane potential can change with an addition or
removal of ions within the cell.
• Ions move in and out of the cell by passing through proteins
that act as ion channels. Whether the ion channels are open
or closed affects the membrane potential.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Nerve Impulses, continued
• Resting Potential
– A neuron is at rest when it is not sending or
receiving a signal.
– When at rest, the neuron is more negatively
charged on the inside than on the outside of
the cell body.
– The electric potential across the cell
membrane when the neuron is at rest is called
the resting potential.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Nerve Impulses, continued
• Action Potential
– When a dendrite or cell body is stimulated, the
permeability of the neuron’s membrane
changes suddenly.
– The membrane potential reverses and the
neuron’s cell body becomes more positively
charged than the exterior of a cell.
• This reverse in polarity begins an action
potential.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Nerve Impulses, continued
• Action Potential, continued
– After the first segment of the neuron is stimulated the
segment next to the first will become stimulated.
• The action potential will continue away from the cell
body.
– Soon after being stimulated, the interior of the neuron
begins to become more and more negative.
• This signals the end of the action potential.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Nerve Impulses, continued
• Action Potential, continued
– A neuron cannot generate another action
potential until it has returned to its resting
potential.
– The period in which a neuron cannot send a
signal is called the refractory period.
– Returning the neuron to its resting potential
requires energy.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Conduction of a Nerve Impulse
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Action Potential
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Communication Between Neurons
• Once an action potential reaches the axon terminal, it
releases neurotransmitters into the synaptic cleft. These
neurotransmitters bind to receptors proteins and open the
ion channels of the new neuron cell.
• If enough ion channels are opened, the action potential will
continue through the new neuron. If not, the nervous signal
will be terminated.
• After the neurotransmitters have opened the ion channels,
they will be cleared out of the synaptic cleft by being
reabsorbed by the neuron that released them or broken
down by enzymes.
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Synaptic Transmission
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Chapter 49
Section 1 Neurons and Nerve
Impulses
Release of Neurotransmitter
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Chapter 49
Section 2 Structure of the Nervous
Systems
Objectives
• Identify the two main parts of the central nervous
system.
• Summarize the functions of the major parts of the
brain.
• Describe the roles of the sensory and motor
divisions of the peripheral nervous system.
• Distinguish between the somatic and autonomic
nervous systems.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Organization of the Nervous System
• The nervous system includes two major
divisions.
– The first division is the central nervous system
and is made up of the brain and the spinal
cord.
• The brain is the control center of the
nervous system.
• The spinal cord carries nerve signals
between the body and the brain.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Structure of the Human Brain
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Chapter 49
Section 2 Structure of the Nervous
Systems
Parts of a Human Brain
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Chapter 49
Section 2 Structure of the Nervous
Systems
Organization of the Nervous System,
continued
• The second division is the peripheral nervous
system and consists of neurons that have cell
bodies and that are not included in the brain and
spinal cord.
– Peripheral neurons send information to and
from the central nervous system.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain
• Cerebrum
– The cerebrum is the upper
part of the brain that receives
sensation and controls
movement.
• The cerebrum is made of two hemispheres, called the
cerebral hemispheres.
• Each hemisphere is made up of four lobes, called the
frontal, parietal, temporal, and occipital.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain, continued
• Cerebrum, continued
– The folded outer layer of the cerebrum is
called the cerebral cortex.
– The cerebral cortex is the portion of the
cerebrum that controls the higher mental
functions, general movement, organ function,
perception, and behavioral reactions.
• The many folds of the cerebral cortex allow
the brain to have a large surface area
and still fit into the skull.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain, continued
• Cerebrum, continued
– The cerebral cortex is called gray matter.
Beneath the gray matter is white matter.
– White matter is made up of myelinated axons,
which link specific regions of the cortex with
each other and with other neural centers.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Cerebrum
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain, continued
• Diencephalon
– This section of the brain is made up of two
parts, the thalamus and hypothalamus.
• The thalamus directs most incoming
sensory signals to the proper region of the
cerebral cortex.
• The hypothalamus helps maintain
homeostasis and directly controls most of
the body’s hormone production.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain, continued
• Brain Stem
– This section of the brain is made up of three
parts: the midbrain, pons, and medulla
oblongata.
• The midbrain relays visual and auditory
information.
• The pons relays communications between
the cerebral hemispheres and the
cerebellum.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain, continued
• Brain Stem, continued
– The last section of the brain stem is the medulla
oblongata. The medulla oblongata serves as both a relay
center and a control center for heart rate, respiration
rate, and other homeostatic activities.
– The brain stem also has a network of neurons called the
reticular formation. This section of the brain stem helps
control respiration and circulation and helps separate
signals that are important from those that are not.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain Stem
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Chapter 49
Section 2 Structure of the Nervous
Systems
Brain, continued
• Cerebellum
– The cerebellum lies below and behind the
cerebral hemispheres and helps to coordinate
muscle action.
– The cerebellum receives sensory impulses
from muscles, tendons, joints, eyes, and ears
and other brain centers.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Cerebellum
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Chapter 49
Section 2 Structure of the Nervous
Systems
Spinal Cord
• The spinal cord is a
column of nervous tissue
that starts at the medulla
oblongata and runs
throughout the vertebral
column.
– The spinal cord is
composed of white and
gray matter.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Parts of a Human Spinal Cord
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Chapter 49
Section 2 Structure of the Nervous
Systems
Peripheral Nervous System
• The central nervous system interacts with the peripheral
nervous system through nerves.
– Nerves are bundled axons and dendrites of many
neurons. Spinal nerves are made up of both a dorsal and
ventral root.
– The dorsal roots carry signals into the central nervous
system from sensory receptors.
• The sensory receptors are neurons that are specialized
to detect stimuli such as light, pressure, and heat.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Peripheral Nervous System, continued
• The peripheral nervous system also contains
ventral roots. Ventral roots contain the axons of
motor neurons.
– Motor neurons are neurons that carry
information from the central nervous system to
muscles and glands.
• Interneurons can also be found in both sections of
the nervous system. Interneurons can relay
information between other neurons.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Peripheral Nervous
System
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Chapter 49
Section 2 Structure of the Nervous
Systems
Sensory Division
• The sensory division of the peripheral nervous
system contains sensory receptors and the
interneurons that connect them to the central
nervous system.
– Sensory receptors receive information from the
body’s external and internal environments.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Motor Division
• The motor division of the peripheral nervous
system allows the body to react to sensory
information.
– The motor division of the peripheral nervous
system is made up of the somatic nervous
system and the autonomic nervous system.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Motor Division, continued
• Somatic Nervous System
– The somatic nervous system contains motor
neurons that control the movement of skeletal
muscles.
• The somatic system is considered voluntary,
but can operate without conscious control.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Motor Division, continued
• Somatic Nervous System, continued
– Somatic system also relays the signals in
reflexes.
– Reflexes are involuntary and often selfprotective movements. An example is the
patellar, or knee-jerk, reflex.
– The patellar reflex is an example of a spinal
reflex, which involves only neurons in the body
and bypasses the brain
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Chapter 49
Section 2 Structure of the Nervous
Systems
Knee-Jerk Response
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Chapter 49
Section 2 Structure of the Nervous
Systems
Reflex
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Chapter 49
Section 2 Structure of the Nervous
Systems
Motor Division, continued
• Autonomic Nervous System
– The autonomic nervous system controls internal
body conditions by regulating smooth muscles
in blood vessels and organs.
• The autonomic system is considered
involuntary, and can be broken up into two
subdivisions.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Motor Division, continued
• Autonomic Nervous System, continued
– The first subdivision of the autonomic nervous
system is the sympathetic division.
• The sympathetic division prepares the body
when activated by physical or emotional
stress.
• For example, pupils dilate and heart rate
increases.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Motor Division, continued
• Autonomic Nervous System, continued
– The second subdivision of the autonomic
nervous system is the parasympathetic division.
• The parasympathetic division controls the
internal environment during routine
conditions.
• For example, pupils constrict and heart rate
decreases.
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Chapter 49
Section 2 Structure of the Nervous
Systems
Physiological Effects of the Autonomic
Nervous System
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Chapter 49
Section 2 Structure of the Nervous
Systems
Comparing the Somatic and Autonomic
Nervous Systems
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Chapter 49
Section 3 Sensory Systems
Objectives
• List the stimuli to which each of the five types of sensory
receptors respond.
• Identify the parts of the ear responsible for hearing and for
maintaining balance.
• Describe the structure of the eye and roles of rods and cones in
vision.
• Discuss how taste and smell are detected.
• Compare the detection of touch, temperature and pain.
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Chapter 49
Section 3 Sensory Systems
Perception of Stimuli
• In order to detect changes in the environment,
organisms use their sense organs.
• Sense organs are organs that receive stimuli and
give rise to the senses such as sight, smell,
hearing and pain.
• Sense organs are part of the sensory division of
the peripheral nervous system.
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Chapter 49
Section 3 Sensory Systems
Sense Organs
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Chapter 49
Section 3 Sensory Systems
Perception of Stimuli, continued
• Receptors and Sense Organs
– Sensory receptors can be categorized based
on the type of stimuli that they respond to.
• Mechanoreceptors respond to movement,
pressure and tension.
• Photoreceptors respond to variations in
light.
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Chapter 49
Section 3 Sensory Systems
Perception of Stimuli, continued
• Receptors and Sense Organs, continued
– Chemoreceptors are sensory receptors that
respond to chemicals.
– Thermoreceptors are sensory receptors that
respond to changes in temperature.
– Pain receptors are sensory receptors that
respond to tissue damage.
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Chapter 49
Section 3 Sensory Systems
Types of Sensory Receptors
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Chapter 49
Section 3 Sensory Systems
Perception of Stimuli, continued
• Receptors and Sense Organs, continued
– Sensory receptors are found in higher concentrations in
the sense organs than in other parts of body.
– When stimulated, these sensory receptors turn the
stimulus into electrical signals and send those signals
to the brain.
– Each signal that is sent to the brain is similar but may
be sent to different parts of the brain to be interpreted.
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Chapter 49
Section 3 Sensory Systems
Hearing and Balance
• The ear performs two main functions: detecting
sound and maintaining balance.
• Sound vibrations are directed into the ear by the
fleshy structure of the outer ear.
• The outer ear is connected to the middle ear by
the auditory canal.
– The auditory canal is also the tube that allows
air into the ear.
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Chapter 49
Section 3 Sensory Systems
Hearing and Balance, continued
• The middle ear begins with the tympanic
membrane.
– The tympanic membrane is also called the
eardrum.
• The Eustachian tube controls the air pressure
beyond the tympanic membrane.
– The Eustachian tube is an opening to the
throat that equalizes the pressure on both
sides of the tympanic membrane.
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Chapter 49
Section 3 Sensory Systems
Tympanic Membrane
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Chapter 49
Section 3 Sensory Systems
Hearing and Balance, continued
• When sound waves hit the tympanic membrane it
begins to vibrate.
• These vibrations cause the three bones of the
middle ear (hammer, anvil, and stirrup) to also
vibrate.
• These vibrations are passed to the oval window
by the stirrup.
– The oval window separates the middle ear
from the inner ear.
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Chapter 49
Section 3 Sensory Systems
Hearing and Balance, continued
• Past the oval window is the inner ear. The inner
ear includes the cochlea.
• The cochlea is a coiled tube consisting of three
fluid-filled chambers that are separated by
membranes.
• The middle chamber is called the organ of Corti
and is the hearing organ.
– The organ of Corti rests on the bottom
membrane in the cochlea.
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Chapter 49
Section 3 Sensory Systems
Hearing and Balance, continued
• The vibrations in the fluid of the cochlea move
the bottom membrane, which causes hair cells to
bend.
– Hair cells are the mechanoreceptors in the ear
and can be easily damaged.
• The bending of the hair cells cause the release of
neurotransmitters.
• These neurotransmitters stimulate the neurons
in the auditory nerve. This stimulation allows
you to hear.
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Chapter 49
Section 3 Sensory Systems
Structure of the Ear
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Chapter 49
Section 3 Sensory Systems
Parts of the Human Ear
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Chapter 49
Section 3 Sensory Systems
Human Hearing
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Chapter 49
Section 3 Sensory Systems
Hearing and Balance, continued
• The ear also helps maintain balance.
• Balance is maintained by mechanoreceptors in
the three fluid-filled semicircular canals of the
inner ear.
– When the head moves the hair cells bend.
– The brain interprets the hair cell movement
and sends out the proper signals to help the
body maintain balance.
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Chapter 49
Section 3 Sensory Systems
Vision
• The eyes detect light and transmit signals to visual
processing areas of the brain.
• The retina is where all structures focus light.
– The retina is the light sensitive layer. It receives
images and transmits them through the optic
nerve to the brain.
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Chapter 49
Section 3 Sensory Systems
Vision, continued
• In order to reach the
retina, light must first
pass through the
cornea, pupil, iris, and
lens.
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Chapter 49
Section 3 Sensory Systems
Parts of the Human Eye
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Chapter 49
Section 3 Sensory Systems
Vision, continued
• The cornea is a transparent membrane that forms the front
portion of the eyeball, where light is first encountered.
• The pupil is the next to receive light and is the opening to
the interior of the eye.
• The amount of light that enters the pupil is controlled by the
colored circular part of the eye, the iris.
• The lens is a crystalline structure that muscles adjust to
focus the light on the retina.
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Chapter 49
Section 3 Sensory Systems
Vision, continued
• The retina interprets light through photoreceptors
that translate light energy into electrical signals
that can be interpreted by the brain.
• The photoreceptors within the eye can be broken
down into two types: rods and cones.
– Rods can detect dim light and play a major role
in noncolor and night vision.
– Cones can distinguish colors and are sensitive
to bright light.
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Chapter 49
Section 3 Sensory Systems
Structure of
the Eye
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Chapter 49
Section 3 Sensory Systems
Comparing Rods and Cones
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Chapter 49
Section 3 Sensory Systems
Taste and Smell
• Chemoreceptors
responsible for taste
are called taste buds
and can be found on
the tongue, the
throat, and the roof
of the mouth.
• Taste buds are
found on the tongue
between bumps
called papillae.
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Chapter 49
Section 3 Sensory Systems
Taste and Smell, continued
• Chemoreceptors in
the nasal passages
that can detect
chemicals in the air
are called olfactory
receptors.
• They are located in
the mucous lining of
the epithelium in the
nasal passage.
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Chapter 49
Section 3 Sensory Systems
Comparing Taste and Smell
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Chapter 49
Section 3 Sensory Systems
Pressure and Temperature
• Mechanoreceptors located throughout the skin
make it possible to sense touch, pressure, and
tension.
• Two types of receptors monitor skin temperature:
hot and cold receptors.
• Pain receptors are located throughout the interior
of the body and at the base of the epidermis.
• Sensory input from sensory receptors travels
in an orderly way to the brain.
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Chapter 49
Section 4 Drugs and the Nervous
System
Objectives
• Define the relationship between addiction and
tolerance.
• Explain the physical basis of cocaine addiction.
• Identify six types of psychoactive drugs.
• List the effects of alcohol and tobacco on the body.
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs
• Drugs are substances that cause a change in a
person’s physical or psychological state.
• A psychoactive drug is a drug that alters the
functioning of the central nervous system.
– A psychoactive drug can be manmade or
natural.
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs of Abuse
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs, continued
• Addiction and Tolerance
– The abuse of a psychoactive drug usually
leads to dependence.
– Dependence is a state in which a person relies
on a drug physically or emotionally in order to
function.
– Dependence often leads to addiction.
Addiction is a condition in which a person can
no longer control his or her drug use.
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Chapter 49
Section 4 Drugs and the Nervous
System
Addiction
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs, continued
• Addiction and Tolerance, continued
– When exposure to a drug is repeated, a person
addicted to the drug can develop a tolerance.
– Tolerance is a characteristic of drug addiction
in which larger and larger amounts of the drug
are needed to achieve the desired sensation.
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Chapter 49
Section 4 Drugs and the Nervous
System
Tolerance
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs, continued
• Addiction and Tolerance, continued
– Once addicted, a user will go into withdrawal if
the drug is taken away.
– Withdrawal includes uncomfortable physical
and psychological symptoms produced when a
physically dependent drug user stops using
drugs.
– Symptoms of withdrawal vary from person to
person.
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs, continued
• Neural Changes
– The effect of psychoactive drugs on the brain
can be illustrated with the example of cocaine.
– Cocaine is a stimulant, or a drug that generally
increases the activity of the central nervous
system.
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs, continued
• Neural Changes, continued
– A normal synapse will allow dopamine to be
reabsorbed correctly by the reuptake receptors
of the presynaptic neuron.
– When cocaine is used, it will bind and block
reuptake receptors. This causes dopamine
molecules to remain in the synaptic cleft
longer.
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Chapter 49
Section 4 Drugs and the Nervous
System
Psychoactive Drugs, continued
• Neural Changes, continued
– The excess dopamine overstimulates the
postsynaptic neuron, which responds by
decreasing the number of receptor proteins on
the postsynaptic neuron.
– In the absences of the drug, dopamine release
returns to normal, but the postsynaptic cell is
understimulated due to a lack of receptors.
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Chapter 49
Section 4 Drugs and the Nervous
System
Action of Cocaine
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Chapter 49
Section 4 Drugs and the Nervous
System
Action of Cocaine, continued
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Chapter 49
Section 4 Drugs and the Nervous
System
Neural Changes Caused by Drug Use
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Chapter 49
Section 4 Drugs and the Nervous
System
Drugs and Abuse
• Alcohol
– Alcohol is a legal drug and can be classified as
a depressant.
– A depressant is a drug that decreases the
activity of the central nervous system.
– A measurement of how much alcohol is in a
person’s blood is called their blood alcohol
concentration or BAC.
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Chapter 49
Section 4 Drugs and the Nervous
System
Effects of Blood Alcohol Concentration
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Chapter 49
Section 4 Drugs and the Nervous
System
Blood Alcohol Concentration and Its Effects
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Chapter 49
Section 4 Drugs and the Nervous
System
Drugs and Abuse, continued
• Tobacco
– Tobacco, like cocaine, is a highly addictive
stimulant. The major drug in tobacco is
nicotine.
– Nicotine is a toxic, addictive alkaloid that is
derived from tobacco and is one of the major
contributors to the harmful effects of smoking.
– Nicotine mimics the action of a
neurotransmitter called acetylcholine.
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Chapter 49
Section 4 Drugs and the Nervous
System
Drugs and Abuse, continued
• Tobacco, continued
– Nicotine is not the only harmful substance
found in tobacco; burning tobacco produces
tars.
• Tars are complex mixtures of chemicals and
smoke particles.
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Chapter 49
Section 4 Drugs and the Nervous
System
Withdrawal
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Chapter 49
Section 4 Drugs and the Nervous
System
Drugs and Abuse, continued
• Tobacco, continued
– Long term use of tobacco can lead to cancer,
chronic bronchitis, and emphysema.
• Chronic bronchitis is an inflammation of the
bronchi and bronchioles.
• Emphysema is a degenerative lung disease
in which alveoli lose their elasticity and
eventually rupture.
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Chapter 49
Standardized Test Prep
Multiple Choice
1. Which of the following is true about the cerebral
cortex?
A. It is located deep in the brain.
B. It is the folded outer covering of the brain.
C. It is part of the peripheral nervous system.
D. It is a lobed, highly folded structure located at the
back of the brain.
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
1. Which of the following is true about the cerebral
cortex?
A. It is located deep in the brain.
B. It is the folded outer covering of the brain.
C. It is part of the peripheral nervous system.
D. It is a lobed, highly folded structure located at the
back of the brain.
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
2. When a neuron is at resting potential, which of the
following is true?
F. Both sides of the cell are equally charged.
G. The inside of the cell is negatively charged.
H. The polarity across the membrane reverses.
J. The outside off the cell is negatively charged.
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
2. When a neuron is at resting potential, which of the
following is true?
F. Both sides of the cell are equally charged.
G. The inside of the cell is negatively charged.
H. The polarity across the membrane reverses.
J. The outside off the cell is negatively charged.
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
3. Which of the following stimuli affects
mechanoreceptors?
A. heat
B. light
C. pressure
D. chemicals
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
3. Which of the following stimuli affects
mechanoreceptors?
A. heat
B. light
C. pressure
D. chemicals
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer
questions 4 and 5. The
graph shows the change in
voltage during an action
potential.
4. How long does the
action potential last?
F. 1 ms
G. 1.5 ms
H. 3 ms
J. 30 ms
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer
questions 4 and 5. The
graph shows the change in
voltage during an action
potential.
4. How long does the
action potential last?
F. 1 ms
G. 1.5 ms
H. 3 ms
J. 30 ms
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer
questions 4 and 5. The
graph shows the change in
voltage during an action
potential.
5. Which point on the
graph represents when
the voltage-gated
sodium channels are
open?
A. 1
B. 2
C. 1 and 2
D. There is not enough
information to determine
the answer.
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer
questions 4 and 5. The
graph shows the change in
voltage during an action
potential.
5. Which point on the
graph represents when
the voltage-gated
sodium channels are
open?
A. 1
B. 2
C. 1 and 2
D. There is not enough
information to determine
the answer.
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Complete the following analogy:
6. stimulant : nicotine :: depressant :
F. alcohol
G. cigarettes
H. neurotransmitters
J. tetrahydrocannabinol (THC)
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Complete the following analogy:
6. stimulant : nicotine :: depressant :
F. alcohol
G. cigarettes
H. neurotransmitters
J. tetrahydrocannabinol (THC)
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the diagram below to answer questions 7 and 8. The
diagram shows a neuron.
7. Which number indicates the structure from which the
neuron receives information from other neurons?
A. 1
B. 2
C. 3
D. 4
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the diagram below to answer questions 7 and 8. The
diagram shows a neuron.
7. Which number indicates the structure from which the
neuron receives information from other neurons?
A. 1
B. 2
C. 3
D. 4
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the diagram below to answer questions 7 and 8. The
diagram shows a neuron.
8. Which number indicates the structure that increases
the speed of action potentials?
F. 1
G. 2
H. 3
J. 4
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Chapter 49
Standardized Test Prep
Multiple Choice, continued
Use the diagram below to answer questions 7 and 8. The
diagram shows a neuron.
8. Which number indicates the structure that increases
the speed of action potentials?
F. 1
G. 2
H. 3
J. 4
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Chapter 49
Standardized Test Prep
Short Response
The effect of a drug on the body varies with the size
of the dose and an individual’s tolerance to the
drug.
Explain the difference between the effective dose
and the lethal dose of a drug.
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Chapter 49
Standardized Test Prep
Short Response, continued
The effect of a drug on the body varies with the size
of the dose and an individual’s tolerance to the
drug.
Explain the difference between the effective dose
and the lethal dose of a drug.
Answer: An effective dose is the dose that causes
the desired response. The lethal dose is the
amount that can kill the user.
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Chapter 49
Standardized Test Prep
Extended Response
Base your answers to parts A & B on the information below.
Both alcohol and tobacco can have a negative effect on
human health.
Part A Susan is addicted to alcohol. Predict what might
happen if she quit drinking.
Part B Mark smokes a pack of cigarettes a day. Describe some
of the health risks Mark faces if he continues to smoke for a
long period of time.
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Chapter 49
Standardized Test Prep
Extended Response, continued
Answer:
Part A She will undergo withdrawal.
Part B Mark will risk cardiorespiratory diseases
including emphysema, bronchitis, and various
forms of cancer.
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