Chapter 7: The Nervous System

Front 1

Receptors capable of sensing touch, pain, temperature changes, and chemical stimuli send information to the ___________ concerning changes in our environment.

Back 1

Central Nervous System

Front 2

A summary of the functions of the nervous system follows:
a. Control of the _______ environment
b. ________ control of movement
3. Programming of ______ ______ reflexes
4. Assimilation of experiences necessary for __________ and _______

Back 2

internal
voluntary
spinal cord
memory and learning

Front 3

The nervous system can be divided into two main parts:

Back 3

CNS and peripheral nervous system

Front 4

The ____ is the portion of the nervous system contained in the skull and the spinal cord.

The ____ consists of nerve cells outside the CNS.

What is the name for nerve cells?

Back 4

CNS
PNS
neurons

Front 5

The sensory division of the PNS is responsible for transmission of neuron impulses from sense organs (receptors) to the CNS through (afferent/efferent) fibers.

Back 5

afferent

Front 6

In the motor division of the PNS, (afferent/efferent) fibers transmit impulses from CNS to effector organs.

Back 6

efferent

Front 7

The motor portion of the PNS can be further subdivided into the ______ motor division (which innervatics skeletal muscle) and the _________ motor division (which innervates effector organs like smooth muscle in the gut, cardiac muscle, and glands)

Back 7

somatic
automatic

Front 8

The functional unit of the nervous system is the ______.

Back 8

neuron

Front 9

Neurons can be divided into three regions:
1.
2.
3.

Back 9

Cell Body
Dendrites
Axons

Front 10

The center of operation for the neuron which contains the nucleus is the _______.

Back 10

cell body.

Front 11

This part of a neuron is a narrow, cytoplasmic attachment that extends from the cell body and serves as a receptive area that can conduct electrical impulses toward the cell body.

Back 11

Dendrites

Front 12

This part of the neuron carries the electrical message away from the cell body toward another neuron or effector organ.

Back 12

Axon

Front 13

The axon may be covered by ________ cells, which forms discontinuous myelin sheath along the length of the axon.

Back 13

Schwann

Front 14

The gaps or spaces between the myelin segments along the axon are called ____________ and play an important role in neural transmission.

Back 14

Nodes of Ranvier

Front 15

True/False In general, the larger the diameter of the axon, the greater the speed of transmission. Thus, those axons with large myelin sheaths conduct impulses more rapidly than small, nonmyelinated fibers.

Back 15

True

Front 16

If there is damage done to the myelin in myelinated nerve fibers, does the nervous system fail to function and lead to multiple sclerosis?

Back 16

yes

Front 17

Neurons are considered "excitable tissue" because of their specialized properties of ________ and _________.

Back 17

irritability
conductivity

Front 18

_________ is the ability of the dendrites and neuron cell body to respond to a stimulus and convert it to a neural impulse.

Back 18

Irritability

Front 19

_______ refers to the transmission of the impulse along the axon. This electrical signal is initiated via some stimulus that causes a change in the normal electrical charge of the neuron.

Back 19

Conductivity

Front 20

At rest, all cells (including neurons) are (positively/negatively) charged on the INSIDE of the cell with respect to the charge on the exterior of the cell.

Back 20

negatively

Front 21

Because there is a difference in charge on the INSIDE of the cell and and OUTSIDE of the cell, a neuron is said to be ________ and this electrical charge difference is termed the ______ _________ __________.

Back 21

polarized
resting membrane potential

Front 22

In normal cells (not neurons) what is the resting membrane potential range?

Back 22

5 to -100 mv

Front 23

In neurons what is the resting membrane potential range?

Back 23

-40 to -75 mv

Front 24

The negative charge is the result of an unequal distribution of _______ ___ across the cell membrane.

Back 24

charged ions

Front 25

The magnitude of the resting membrane potential is primarily determined by two factors:
1. the __________ of the plasma membrane to different ion concentrations
2. the difference in ion concentrations between the __________ and ___________ fluids.

Back 25

permeability
intracellular, extracellular

Front 26

What three ions are commonly used?

Back 26

Sodium
Potassium
Calcium
sometimes Chlorine

Front 27

The permeability of the neuron membrane to potassium, sodium and other ions is regulated by proteins within the membrane that function as ________ that can be open or closed by "gates" within the channel.

Back 27

channels

Front 28

The concentration of potassium is (high/low) inside the cell while sodium is (high/low) outside the cell.

Back 28

high
high

Front 29

At rest, all sodium channels are (open/closed) whereas a few potassium channels are open. This means that there are more potassium ions leaving the cell than sodium ions leaking into the cell. this results in a net loss of positive charges from the inside of the membrane, thus making the resting membrane potential negative.

Back 29

closed

Front 30

What prevents the concentration gradients for sodium and potassium ions from decreasing?

True/False This pump does NOT help generate an action potential because it exchanges three sodium ions for every two potassium ions.

Back 30

A sodium/potassium pump which utilizes ATP.

False it DOES

Front 31

A neural message is generated when a stimulus of sufficient strength reaches the neuron membrane and opens _____ gates, which allows _______ ions to diffuse into the neuron, making the inside more and more positive (depolarizing the cell)

Back 31

sodium

Front 32

When depolarization reaches a critical value called a "_______", the sodium gates open wide and an ______ _________, or nerve impulse is formed.

Back 32

threshold
action potential

Front 33

After an action potential has been generated, a sequence of ionic exchanges occurs along the axon to propagate the nerve impulse in a sequential fashion at the _____ ___ ________.

Back 33

Nodes of Ranvier

Front 34

________ occurs immediately following depolarization, resulting in a return of the resting membrane potential with the nerve ready to be stimulated again.

Back 34

Repolarization

Front 35

Repolarization occurs when after depolarization, with a slight time delay, causes a brief increase in membrane permeability to _________. As a result, ________ leaves the cell rapidly, making the inside of the cell more negative. Second, the _______ gates within the membrane close, and sodium entry into the cell is slowed.

Back 35

Potassium
potassium
sodium

Front 36

True/False An action potential can be stopped and is not described as an "all-or-none" action.

Back 36

False

Front 37

The sodium/potassium pump requires energy (ATP) and is just is therefore an _________ transport pump that moves (two/three) sodium molecules out and (two/three) potassium molecules in.

Back 37

active
three
two

Front 38

Neurons communicate with other neurons at junctions called ________.

Back 38

synapses

Front 39

A synapse is a small gap between the synaptic _________ and the _________ neuron and a dendrite of a __________ neuron

Back 39

endfoot
presynaptic
postsynaptic

Front 40

Communication between neurons occurs via a process called synaptic ___________, and it happens when a sufficient amount of a specific neurotransmitter is released from synaptic vesicles contained in the presynaptic neuron.

Back 40

transmission

Front 41

The nerve impulse results in the synaptic vesicles releasing stored neurotransmitters into the _______ ________.

Back 41

synaptic cleft

Front 42

Neurotransmitters that cause the depolarization of membranes are ___________ transmitters.

Back 42

excitatory

Front 43

After release into the synaptic cleft, these neurotransmitters bind to "______" on the target membrane, which produces a series of graded depolarizations in the dendrites and cell body.

Back 43

receptor

Front 44

Graded depolarizations are known as _________ __________ ____________.

Back 44

excitatory postsynaptic potentials

Front 45

True/False If sufficient amounts of the neurotransmitter are released, the postsynaptic neuron is depolarized to threshold and an action potential is generated.

Back 45

True

Front 46

Excitatory Postsynaptic Potentials can bring the postsynaptic neuron to threshold in two ways:
1.
2.

Back 46

Temporal Summation
Spatial Summation

Front 47

The summing of several EPSPs from a single presynaptic neuron over a short time period is termed ________ summation.

How many EPSPs are estimated to create an action potential?

Back 47

Temporal

about 50

Front 48

The summing of EPSPs from several different presynaptic inputs is known as ________ summation.

Back 48

spatial

Front 49

A common neurotransmitter, which also happens to be the transmitter at the nerve/muscle junction is ______________.

Back 49

acetylcholine

Front 50

Upon release into the synaptic cleft, ATC binds to receptors on the postsynaptic membrane and opens "channels", which allow _______ to enter the muscle cell. When enough sodium enters the postsynaptic membrane of a neuron or muscle, _________ results. To prevent chronic depolarization of the postsynaptic neuron, the neurotransmitter must be broken down into less active molecules via enzymes found in the ________ cleft. In the case of acetylcholine, the degrading enzyme is ___________.

Back 50

sodium
depolarization
synaptic
acetylcholinesterase

Front 51

Inhibitory transmitters cause a ______________ of the postsynaptic membrane.

Back 51

hyperpolarization

Front 52

This hyperpolarization of the membrane is called an ____________ __________ _________.

Back 52

inhibitory postsynaptic potential

Front 53

Receptors that provide the CNS with information about body position are called ___________, or kinesthetic receptors, and include muscle spindles, Golgi tendon organs, and joint receptors.

Back 53

proprioceptors

Front 54

The term __________ means conscious recognition of the position of body parts with respect to one another as well as recognition of limb-movement rates.

Back 54

kinesthesia

Front 55

There are three principle types of joint proprioceptors:

Back 55

1. Free nerve endings
2. Golgi-type receptors
3. Pacinian corpuscles

Front 56

What joint proprioceptors are sensitive to touch and pressure and are the most abundant?

Back 56

Free nerve endings

Front 57

What type of joint proprioceptor is not to be confused with Golgi tendon organs found in muscles but is found in ligaments around joints?

Back 57

Golgi-type receptors

Front 58

What type of joint proprioceptor is found in the tissues around joints and adapts rapidly following the initiation of movement? This rapid adaptation presumably helps detect the rate of joint rotation.

Back 58

Pacinian corpuscles

Front 59

Skeletal muscle contains several types of sensory receptors. Theses include:
1.
2.
3.

Back 59

1. Chemoreceptors
2. Muscle spindles
3. Golgi Tendon organs

Front 60

What type of skeletal muscle sensory receptor are specialized free nerve endings that send information to the central nervous system in response to changes in muscle pH, concentrations of extracellular potassium, and changes in oxygen and carbon dioxide tensions?

Back 60

Chemoreceptors

Front 61

For the nervous system to properly control skeletal muscle movements, it must receive continuous sensory feedback from the contracting muscle. _____________ provide the central nervous system with feedback concerning the tension developed by the muscle, while the ____________ provides sensory information concerning the relative muscle length.

Back 61

Golgi tendon organ
muscle spindle

Front 62

True/False Muscles that require the finest degree of motor control, such as the muscles of the hands, have the lowest density of spindles.

Back 62

False, highest

Front 63

The muscle spindle is composed of several thin muscle cells (called _________ fibers) that are surrounded by a connective tissue sheath. Like normal skeletal muscle fibers (called _______ fibers), muscle spindles insert into connective tissue within the muscle. Therefore, muscle spindles run (parallel/perpendicular) with muscle fibers.

Back 63

intrafusal
extrafusal
parallel

Front 64

Muscle spindles contain two types of sensory nerve endings. The ________ endings respond to dynamic changes in muscle length. The second type of sensory ending is called the _______ ending, and it does not respond to rapid changes in muscle length, but provides the central nervous system with continuous information concerning static muscle length.

Back 64

primary
secondary

Front 65

In addition to the sensory neurons, muscle spindles are innervated by ______ motor neurons, which stimulate the intrafusal fibers to contract simultaneously with extrafusal fibers.

Back 65

gamma

Front 66

Muscle spindles are responsible for the observation that rapid stretching of skeletal muscles results in a ______ contraction. This is called the _____ _____ and is common in all muscles, but is most dramatic in the extensor muscles of the limbs.

Back 66

reflex
stretch reflex

Front 67

In the stretch reflex, the muscle spindles detect stretch of the muscle, ______ neurons conduct action potentials to the spinal cord, and ________ with ______ motor neurons. Stimulation of the alpha motor neurons causes the muscle to contract and resist being stretched.

Back 67

sensory
synapse
alpha

Front 68

The ______ ________ __________ continuously monitor the tension produced by muscle contraction. When activated, GTOs send information to the spinal cord via ______ neuron, which in turn excite (inhibitory/excitatory) neurons. This reflex helps prevent excessive force generation

Back 68

Golgi Tendon Organ
sensory

Front 69

______ _________ are sensitive to changes in chemical environment surrounding a muscle, and provide CNS with information about the metabolic rate of muscular activity.

Back 69

Muscle Chemoreceptors

Front 70

_______ are rapid, unconscious means of reacting to stimuli.

Back 70

Reflexes

Front 71

In a reflex, a _______ nerve sends impulse to spinal column, _________ activate motor neurons, motor neurons control movement of ________.

Back 71

sensory
interneurons
muscles

Front 72

In _________ _________, excitatory postsynaptic potentials cause muscles to withdraw from stimulus, and inhibitory postsynaptic potentials cause muscles to contract to antagonistic muscles.

Back 72

Reciprocal inhibition

Front 73

The ________ motor portion of the peripheral nervous system is responsible for carrying neural messages from the spinal cord to skeletal muscle fibers.

Back 73

somatic

Front 74

The somatic neuron that innervates skeletal muscle fibers is called a _____ neuron. The cell body of motor neurons is located with the _____ ____.

Back 74

motor
spinal cord

Front 75

The axon of the motor neuron leaves the spinal cord as a spinal nerve and extends to the muscle that it is responsible for innervating. Once the axon reaches the muscle, the axon splits into collateral branches; each collateral branch innervates a single muscle fiber. Each motor neuron and all the muscle fibers that it innervates is known as a ______ ______.

Back 75

motor unit

Front 76

The number of muscle fibers innervated by a single motor neuron is called the ________ _____. Low ratio in muscles that require fine motor control.

Back 76

innervation ratio

Front 77

The ________ ___________ is located in the inner ear and is responsible for maintaining general equilibrium and balance. It is sensitive to changes in linear and angular acceleration and controls head and eye movement during exercise.

Back 77

Vestibular apparatus

Front 78

The brain can be divided into what three parts:

Back 78

1. Brain stem
2. Cerebrum
3. Cerebellum

Front 79

The ______ ______ is located inside the base of the skull just above the spinal cord.

Back 79

brain stem

Front 80

The major structures of the brain stem are the
1.
2.
3.
as well as the _________ ________.

Back 80

medulla
pons
midbrain
reticular formation

Front 81

The brainstem is responsible for many ________ functions, cardiorespiratory _______, and complex _________.

Back 81

metabolic
control
reflexes

Front 82

The __________ is the large dome of the brain that is divided into left and right cerebral hemispheres.

Back 82

Cerebrum

Front 83

The outermost layer of the cerebrum is called the ________ ______.

Back 83

Cerebral cortex

Front 84

The cerebral cortex performs three very important motor behavior functions:
1.
2.
3.

Back 84

The organization of complex movement
The storage of learned experiences
The reception of sensory information

Front 85

The portion of the cerebral cortex that is most concerned with voluntary movement is termed _______ ______.

Back 85

motor cortex

Front 86

The __________ plays an important role in coordinating and monitoring complex movement.

Back 86

cerebellum

Front 87

The cerebellum has connections to the _______ cortex, brain stem, and _______ cord.

Back 87

motor, spinal

Front 88

An __________ _______ results in blood vessel damage and is the leading cause of death in athletes.

Back 88

intracranial hemmorage

Front 89

A ___________ is a clinical syndrome characterized by impairment of neural functions.

Back 89

concussion

Front 90

Evidence exists that the spinal cord plays an important role in ___________ movement with groups of neurons controlling certain aspects of motor activity.

Back 90

voluntary

Front 91

The spinal mechanism by which a voluntary movement is translated into appropriate muscle action is termed ________ ______.

Back 91

spinal tuning

Front 92

The first step in performing a voluntary movement occurs in ___________ and ________ motivational areas, which send signals to the association cortex, which forms a "rough draft" of the planned movement.

Back 92

subcortical
cortical

Front 93

The movement plan is then sent to both the __________ and basal ganglia. These structures cooperate to convert the rough draft into precise temporal and spacial excitation programs.

Back 93

cerebellum

Front 94

The ___________ is important for making fast movements, while the ______ _______ are more responsible for making slow movements.

Back 94

cerebellum
basal ganglia

Front 95

From the cerebellum and basal ganglia, the precise program is sent through the ________ to the motor cortex, which forwards the message down to neurons for "spinal tuning" and finally to skeletal muscle.

Back 95

thalamus

Front 96

Feedback to the CNS from the muscle receptors and proprioceptros allows the modification of _______ programs, if necessary.

Back 96

motor

Front 97

The ________ _______ ______ plays an important role in maintaining the constancy of the body's internal environment. In contrast to somatic motor nerves, these nerves innervate effector organs (smooth muscle, cardiac muscle) which are not usually under voluntary control.

Back 97

automatic nervous system

Front 98

The automatic nervous system can be separated both functionally and anatomically into two divisions:
1.
2.

Back 98

sympathetic
parasympathetic

Front 99

The sympathetic division releases ___________ and (excites/inhibits) an effector organ.

Back 99

norepinephrine
excites

Front 100

The parasympathetic division releases ___________ and (excites/inhibits) an effector organ.

Back 100

acetylcholine
inhibits

Front 101

True/False Research indicates that exercise can improve brain (cognitive) function, by stimulating formation of new neurons, improving brain vascular function and blood flow, reduces peripheral factors for cognitive decline, and enhances learning and memory.

Back 101

True