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Nervous System
Section 1: Structure of the Nervous System
Section 2: Organization of the Nervous System
Section 3: The Senses
Section 4: Effects of Drugs
Neurons
Neurons are specialized nerve cells that help you gather information about your environment, interpret the information, and react to it.
Structure of the Nervous System
Nervous System
Neurons consist of three main regions: the dendrites, a cell body, and an axon.
Section 1
Dendrites pass signals they receive on to the cell body in electrical impulses.
Nervous System
The axon passes those impulses on to the other neurons or muscles.
Structure of the Nervous System
Section 1
There are three kinds of neurons: sensory neurons, interneurons, and motor neurons.
Nervous System
Sensory neurons send impulses from receptors in the skin and sense organs to the brain and spinal cord.
Interneurons carry impulses to motor organs.
Structure of the Nervous System
Section 1
Nervous System
Structure of the Nervous System
Motor neurons carry impulses away from the brain and spinal cord to a gland or muscles, resulting in a secretion
or movement. The nerve impulse
completes a reflex arc, or a nerve pathway thatconsists of a sensory neuron, an interneuron, and a motor neuron.
Section 1
Nervous SystemSection 1
A Nerve Impulse
Nervous System
Neurons at rest do not conduct impulses.
Sodium ions (Na+) collect on the outside of the cell membrane.
Structure of the Nervous System
Section 1
Potassium ions (K+) collect on the inside of the cell membrane.
Nervous System
Structure of the Nervous System
Negatively charged proteins actively transport sodium ions out of the cell andpotassium ions into the cell.
Section 1
An Action Potential
Nervous System
A nerve impulse is also known as an action potential.
The minimum stimulus to cause an action potential to be produced is called a threshold.
Structure of the Nervous System
Section 1
When a stimulus reaches the threshold, channels open in the plasma membrane.
Nervous System
Sodium ions are rapidly pumped through these channels causing a temporary change in the electrical charges.
More positive charges are now inside the membrane.
Structure of the Nervous System
Section 1
The now positive charge inside the membrane causes other channels to open and the potassium is quickly pumped out of the cell.
Nervous System
The potassium restores the positive charge outside the cell.
Structure of the Nervous System
Section 1
This rapid positive to negative to positive charge reversal moves along the axon like a wave.
Nervous System
The movement can be seen by finding the sodium-potassium reversal pattern in the three diagrams.
Structure of the Nervous System
Section 1
Nervous SystemSection 1
Nodes along the axon allow ions to pass through the myelin layer to the plasma membrane.
Nervous System
The ions jump from node to node and increase the speed of the impulse.
Speed of an Action Potential
Structure of the Nervous System
Section 1
Nervous SystemSection 1
The small gap between the axon of one neuron and the dendrite of another neuron is called a synapse.
Nervous System
An action potential is carried across these gaps by neurotransmitters.
The Synapse
Structure of the Nervous System
Section 1
Nervous SystemSection 1
The nervous system consists of two major divisions: the central nervous system and the peripheral nervous system.
Organization of the Nervous System
Nervous SystemSection 2
The Central Nervous System
Nervous System
The central nervous system (CNS) is made up mostly of interneurons.
Coordinates all of the body’s activities
Relays messages, processes information, and analyzes responses
Organization of the Nervous System
Section 2
The Brain
Nervous System
The brain is sometimes called the control center of the entire body.
Divided into the cerebrum, the cerebellum, and the brain stem.
Organization of the Nervous System
Section 2
The cerebrum is divided into two halves called the left and right hemispheres.
Nervous System
The functions of the brain include thought processes (learning), memory, language, speech, voluntary body movements, and sensory perception.
Organization of the Nervous System
Section 2
The cerebellum controls balance, posture, and coordination.
Nervous System
The skeletal muscles are controlled to make your motor skills coordinated and smooth.
Organization of the Nervous System
Section 2
The brain stem connects the brain and spinal cord and is composed of the medulla oblongata and the pons.
Nervous System
The medulla oblongata helps control breathing rate, heart rate, and blood pressure.
The pons also aids in breathing.
Organization of the Nervous System
Section 2
The hypothalamus, located between the brain stem and the cerebrum, is essential for homeostasis.
Nervous System
Regulates body temperature, thirst, appetite, and water balance.
Organization of the Nervous System
Section 2
The Spinal Cord
Nervous System
Nerve column that extends from the brain to the lower back.
Protected by the vertebrae
Processes reflexes
Organization of the Nervous System
Section 2
The Peripheral Nervous System
Nervous System
A nerve is a bundle of axons and may contain sensory and motor neurons.
The peripheral nervous system (PNS) contains all the neurons that are not part of the central nervous system.
Organization of the Nervous System
Section 2
The Somatic Nervous System
Nervous System
Nerves in the somatic nervous system relay information from external sensory receptors to the central nervous system, and motor nerves relay information from the central nervous system to skeletal muscles.
Voluntary movements and reflexes are a part of the somatic nervous system.
Organization of the Nervous System
Section 2
The Autonomic Nervous System
Nervous System
The autonomic nervous system carries impulses from the central nervous system to the heart and other internal organs.
The body responds involuntarily, not under conscious control.
Organization of the Nervous System
Section 2
There are two branches of the autonomic nervous system.
Nervous System
The sympathetic nervous system is most active in times of emergency or stress when the heart rate and breathing rate increase.
The parasympathetic nervous system is most active when the body is relaxed.
Organization of the Nervous System
Section 2
Nervous SystemSection 2
Taste and Smell
Specialized neurons in your body enable you to taste, smell, hear, see, and touch, and to detect motion and temperature.
The Senses
Nervous System
Taste buds detect combinations of chemicals that we identify as sweet, sour, salty, and bitter.
Section 3
Receptors associated with taste and smell are located in the mouth and nasal cavity.
Nervous System
The Senses
Signals from these receptors work together to createa combined effect in the brain.
Section 3
Sight
Light travels through the cornea and the pupil to the lens.
Nervous System
The lens focuses the image on the retina.
The Senses
Rods and cones in the retina providelight-sensitivity and information about color.
Section 3
Hearing
Nervous System
The Senses
Sound waves enter the auditory canal andcause a membrane, called the tympanum, at the end of the ear canal to vibrate.
These vibrationscause the cochlea to generate nerve impulses that are interpreted by the brain.
Section 3
Balance The semicircular canals, located in the
inner ear, transmit information about body position and balance to the brain.
Nervous System
The Senses
Section 3
Touch
Many types of sensory receptors that respond to temperature, pressure, and pain are found in the epidermis and dermis layers of the skin.
Nervous System
The Senses
Section 3
How Drugs Work
A drug is a substance, natural or artificial, that alters the function of the body.
Effects of Drugs
Nervous SystemSection 4
Nervous SystemSection 4
Some drugs affect the nervous system in the following ways:
Nervous System
can cause an increase in the amount of a neurotransmitter that is released into a synapse
can block a receptor site on a dendrite, preventing a neurotransmitter from binding
can prevent a neurotransmitter from leaving a synapse
can imitate a neurotransmitter
Effects of Drugs
Section 4
Nervous System
Effects of Drugs
Many drugs that affect the nervous systeminfluence the level of a neurotransmitter called dopamine.
Normally, dopamine is removed from a synapse by beingreabsorbed by the neuron that released it.
Section 4
Nervous System
Classes of Commonly Abused Drugs
Stimulants
Drugs that increase alertness and physical activity
Nicotine
Caffeine
Effects of Drugs
Section 4
Nervous System
Depressants
Drugs that tend to slow down the central nervous system
Alcohol
Inhalants
Illegal drugs
Effects of Drugs
Section 4
Nervous System
Tolerance and Addiction
Tolerance occurs when a person needs more and more of the same drug to get the same effect.
The psychological and/or physiological dependence on a drug is addiction.
Effects of Drugs
Section 4
Nervous System
Chapter Resource Menu
Chapter Diagnostic Questions
Formative Test Questions
Chapter Assessment Questions
Standardized Test Practice
Glencoe Biology Transparencies
Image Bank
Vocabulary
AnimationClick on a hyperlink to view the corresponding feature.
Chapter
connected.mcgraw-hill.com
1. A2. B3. C4. D
CDQ 1
Which is not one of the main parts of a neuron?
A. axon
B. cell body
C. dendrites
D. nucleus
Nervous System
Chapter Diagnostic Questions
Chapter
1. A2. B3. C4. D
CDQ 2
Nervous System
Chapter Diagnostic Questions
Another name for a nerve impulse is _______.
A. synapse
B. threshold
C. reflex arc
D. action potential
Chapter
1. A2. B3. C4. D
CDQ 3
Nervous System
Chapter Diagnostic Questions
What occurs when a motor neuron synapses with a muscle cell?
A. muscle contracts
B. muscle relaxes
C. pain
D. numbness
Chapter
1. A2. B3. C4. D
FQ 1
Nervous System
What type of neuron begins a reflex arc?
A. interneuron
B. motor neuron
C. sensory neuron
D. transmitter neuron
Section 1 Formative Questions
Chapter
1. A2. B3. C4. D
FQ 2
Nervous System
What is another name for nerve impulse?
A. synapses
B. threshold
C. action potential
D. neurotransmitter
Chapter
Section 1 Formative Questions
1. A
2. B
FQ 3
Nervous System
A stronger stimulus will cause a stronger action potential.
A. TrueB. False
Chapter
Section 1 Formative Questions
1. A2. B3. C4. D
FQ 4
Nervous System
When a neuron is at rest, what maintains the high concentration gradients of potassium ions inside the cell and sodium ions outside the cell?
A. diffusion
B. osmosis
C. active transport
D. ion channels
Chapter
Section 1 Formative Questions
1. A2. B3. C4. D
FQ 5
Nervous System
Which is not part of the central nervous system?
A. brain
B. spinal cord
C. interneurons
D. sensory neurons
Chapter
Section 1 Formative Questions
1. A2. B3. C4. D
FQ 6
Nervous System
What does the cerebrum regulate?
A. breathing and heart ratesB. complex motor skillsC. sleep, aggression, and fearD. voluntary body movements
Chapter
Section 2 Formative Questions
1. A
2. B
FQ 7
Nervous System
Some reflexes are processed only in the spinal cord and do not need input from the brain.
A. TrueB. False
Chapter
Section 2 Formative Questions
1. A2. B3. C4. D
FQ 8
Nervous System
What is a nerve?
A. a bundle of axons
B. a chain of neurons
C. a sensory synapse
D. a series of impulses
Chapter
Section 2 Formative Questions
1. A2. B3. C4. D
FQ 9
Nervous System
What part of the nervous system is usually under voluntary control?
A. autonomic nervous systemB. somatic nervous systemC. sympathetic nervous systemD. parasympathetic nervous system
Chapter
Section 2 Formative Questions
1. A2. B3. C4. D
FQ 10
Nervous System
What are sensory receptors?A. cells that create action potentials and
thresholdsB. localized areas of the central nervous systemC. chemicals that cross a synapse between two
nerve cellsD. specialized neurons for detecting the world
around you
Chapter
Section 3 Formative Questions
1. A2. B3. C4. D
FQ 11
Nervous System
Which part of the eye contains light-detecting receptors?
Chapter
Section 3 Formative Questions
1. A2. B3. C4. D
FQ 12
Nervous System
What is the function of the optic nerve?
A. It forms a visual image.B. It controls the muscles of the iris.C. It interprets light intensity and colors.D. It sends action potentials to the brain.
Chapter
Section 3 Formative Questions
1. A2. B3. C4. D
FQ 13
Nervous System
Where are sound vibrations converted into nerve impulses?
Chapter
Section 3 Formative Questions
1. A2. B3. C4. D
FQ 14
Nervous System
Where are the sensory receptors that detect your body’s position and motion?
Chapter
Section 3 Formative Questions
1. A2. B3. C4. D
FQ 15
Nervous System
Why is caffeine a drug?
A. It is a depressant.B. It is an artificial substance. C. It influences the nervous system.D. It builds tolerance to its effects.
Chapter
Section 4 Formative Questions
1. A2. B3. C4. D
FQ 16
Nervous System
Which neurotransmitter is influenced by nicotine and amphetamines, and is involved with most types of addiction?
A. adenosine
B. dopamine
C. epinephrine
D. serotonin
Chapter
Section 4 Formative Questions
1. A2. B3. C4. D
FQ 17
Nervous System
Which is not a stimulant?
A. alcohol
B. caffeine
C. nicotine
D. methamphetamine
Chapter
Section 4 Formative Questions
1. A2. B3. C4. D
FQ 18
Nervous System
What is the term for the body’s decreased response to a drug?
A. addiction
B. dependence
C. tolerance
D. withdrawal
Chapter
Section 4 Formative Questions
1. A2. B3. C4. D
FQ 19
Nervous System
When people who are addicted try to quit, why is it difficult to resist going back to the drug?
A. Adenosine levels increase.
B. Dopamine levels decrease.
C. The central nervous system slows down.
D. Action potentials in neurons become stronger.
Chapter
Section 4 Formative Questions
1. A
2. B
FQ 20
Nervous System
Physiological dependence on a drug is stronger than psychological dependence.
A. TrueB. False
Chapter
Section 4 Formative Questions
1. A2. B3. C4. D
CAQ 1
Nervous System
Name the part of the brain that is responsible for memory.
A. hypothalamus
B. medulla oblongata
C. cerebrum
D. cerebellum
Chapter Assessment Questions
Chapter
Contrast the functions of the cerebellum and the cerebrum.
Nervous System
Answer: The cerebellum controls balance,coordination, and motor skills. The cerebrum controls learning, memory, speech, voluntary body movements, and sensory perception.
Chapter Assessment Questions
CAQ 2
Chapter
1. A2. B3. C4. D
CAQ 3
Nervous System
Chapter Assessment Questions
What part of the brain is identified in the image?
A. pons
B. cerebrum
C. hypothalamus
D. medulla oblongata
Chapter
1. A2. B3. C
STP 1
Nervous System
How do nerve impulses travel in a neuron?
A. dendrite cell body axon
B. dendrite cell body axon
C. dendrite cell body axon
Standardized Test Practice
Chapter
1. A2. B3. C4. D
STP 2
Nervous System
Standardized Test Practice
What carries signals from the axon of one neuron to the dendrite of another neuron?
A. interneurons
B. ion channels
C. neural nodes
D. neurotransmitters
Chapter
1. A2. B3. C4. D
STP 3
Nervous System
Standardized Test Practice
Which word best describes thehypothalamus?
A. processor
B. reflexor
C. regulator
D. transmitter
Chapter
1. A2. B3. C4. D
STP 4
Nervous System
Standardized Test Practice
What part of the brain is highly developed in animals that have finely tuned balance and complex coordination?
A. cerebellum
B. medulla
C. thalamus
D. temporal lobe
Chapter
1. A2. B3. C4. D
STP 5
Nervous System
Standardized Test Practice
How do the sympathetic and parasympathetic nervous systems act together?
A. They send and receive neurotransmitters.B. They send opposing signals to the same organs.C. They balance voluntary and involuntary
responses.D. They receive the same impulses from different
receptors.
Chapter
1. A2. B3. C4. D
STP 6
Nervous System
Standardized Test Practice
Why is this receptor located closest to the surface of the skin?
A. It detects cold.
B. It detects heat.
C. It detects heavy pressure.
D. It detects light touch.
Chapter
1. A2. B3. C4. D
STP 7
Nervous System
Standardized Test Practice
What substances in the body are most closely associated with a drug’s influence on the nervous system?
A. endorphins
B. Na+ and K+ ions
C. neurotransmitters
D. proteins
Chapter
1. A2. B3. C4. D
STP 8
Nervous System
Standardized Test Practice
Where in the nerve pathway do drugs have their primary effect?
A. axons
B. dendrites
C. synapses
D. myelin sheaths
Chapter
1. A2. B3. C
STP 9
Nervous System
Standardized Test Practice
Which step is blocked by cocaine?
Chapter
Glencoe Biology Transparencies
Nervous SystemChapter
Image Bank
Nervous SystemChapter
neuron
dendrite
cell body
axon
reflex arc
action potential
threshold
node
synapse
neurotransmitter
Nervous System
Vocabulary
Section 1
Section 1
central nervous
system
peripheral nervous
system
cerebrum
medulla oblongata
pons
hypothalamus
somatic nervous
system
autonomic nervous
system
sympathetic
nervous system
parasympathetic
nervous system
Nervous System
Vocabulary
Section 2
Section 2
taste bud
lens
retina
rods
cochlea
semicircular canal
Nervous System
Vocabulary
Section 3
Section 3
drug
dopamine
stimulant
depressant
tolerance
addiction
Nervous System
Vocabulary
Section 4
Section 4
Nervous System
Animation
Rapid Reflex Arc
Action Potential
Visualizing Action Potential
Impulse Movement
Chapter
Nervous SystemChapter
Nervous SystemChapter
Nervous SystemChapter
Nervous SystemChapter
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