2. THE NERVOUS SYSTEM What is the girl doing? What keeps her in
equilibrium? How does she react to the crowd while she is
performing? What about the boy? What are the things he pays
attention to while walking? Can the girl and the boy do several
things at the same time? What particular body system controls all
their actions?
3. THE NERVOUS SYSTEM The nervous system is the most complex
and highly developed system of all the body systems. It allows you
to respond to all things in your environment. It tells you what you
see. It helps you distinguish between various sounds that you hear.
It keeps you in equilibrium. It controls the muscles of your hands,
arms and other body parts. It informs you when you are tired, when
you are hungry, when you are thirsty and so on. It stores
information which you may use within a second, a minute or even
days, months or several years later.
4. It is responsible for your thinking, feelings, attitudes and
behavior. You usually experience all these things without
consciously being aware of it. Your nervous system can do all these
things because of billions of nerve cells throughout your body,
your brain, the control center of the nervous system and the spinal
cord where most messages from the brain travel through. The nervous
system is considered to be the communication system of your body.
Do you know why?
5. PARTS OF THE NERVOUS SYSTEM Lesson 1
6. Shown are the three different body systems. How fast can you
identify each body system? The simple mental exercise you have just
done, no matter how easy it may be, involves your nervous system.
You used your eyes to see the different body systems. More
importantly, you used your brain to distinguish one body system
from another. Do you know how you were able to do this? What makes
up the nervous system? What does the nervous system do?
7. PARTS OF THE NERVOUS SYSTEM The nervous system is a network
of nerve cells called neurons that coordinate and control the
various activities of the body, both voluntary and involuntary. It
is made up of the brain, the spinal cord and the nerves. The
nervous system has two main parts. These are the central nervous
system (CNS) and the peripheral nervous system (PNS). The central
nervous system includes the brain and spinal cord. The peripheral
nervous system includes the nerves that are linked with the central
nervous system and their motor and nerve endings.
8. THE CENTRAL NERVOUS SYSTEM The brain and spinal cord, as
mentioned earlier, make up the central nervous system. The brain
and the spinal cord are both protected by bone structures. The
brain is protected by the skull. It is the control center of the
nervous system. The spinal cord on the other hand is protected by
the spinal column. Messages to and from the body travel through the
spinal cord. Both the brain and the spinal cord are also protected
by certain membranes called the meninges. The central nervous
system stores and processes information and sends information to
muscles and glands.
9. THE PERIPHERAL NERVOUS SYSTEM The peripheral nervous system
consists of 43 pairs of nerves leading from the brain and spinal
column to other parts of the body. Twelve pairs of these nerves are
the cranial nerves that lead from the brain and 31 pairs are spinal
nerves that originate in the spinal cord. The peripheral nervous
system carries messages to and from the central nervous
system.
10. THE AUTONOMIC NERVOUS SYSTEM The autonomic nervous system
is part of the peripheral nervous system. It is so called because
it is self-acting and not under control of the will. The autonomic
nervous system is a built-in control. It is responsible in
controlling involuntary actions. In other words, it controls the
automatic movement of internal organs such as the lungs, heart,
glands, urinary bladder and alimentary canal. The alimentary canal
consists of the mouth, esophagus, stomach, small intestine, large
intestine and rectum.
11. The autonomic nervous system also keeps these parts
functioning well. If it were not for the ANS, life would become
impossibly complicated. Our attention would have to be devoted at
all times to such matters as speeding up or slowing down the
heartbeat, dilating or constricting the pupil of the eye, bringing
about secretion from different parts of the body and checking these
secretions.
12. The autonomic nervous system can be divided into two parts:
the sympathetic system and the parasympathetic system. The
sympathetic system speeds up the heartbeat and prepares the body
for fight or flight. It is a part of the ANS that works when you
are active or under emotional stress. The parasympathetic nervous
system is the part of the ANS that generally slows down the bodys
functions. For example, when you are sleeping, it slows down the
heartbeat and rate of breathing. It is most active when you are
resting.
13. HOW THE NERVOUS SYSTEM WORKS The nervous system is the
bodys communication network. Nerves run throughout the body,
carrying messages to the brain through the spinal cord. Nerve cells
in the brain receive messages from all over the body. The brain
processes these messages and sends a response back to other parts
of the body through other nerve cells. Most of these messages
travel through the spinal cord. Did you know that your nervous
system sends messages as fast as 185 miles per hour?
14. REMEMBERING SCIENCE FACTS The two main parts of the nervous
system are the central nervous system and peripheral nervous
system. The central nervous system consists of the brain and the
spinal cord. The CNS stores and processes information and sends
information to muscles and glands. The peripheral nervous system
consists of the nerves that are linked with the central nervous
system and their motor and nerve endings. It carries messages to
and from the central nervous system. The autonomic nervous system
controls involuntary action. The nervous system is the bodys
communication network.
15. REACHING OUT: IDENTIFICATION 1. A part of the nervous
system consisting of the nerves that are linked with the central
nervous system 2. A part of the nervous system which consists of
the brain and the spinal cord 3. The body system with a different
network of nerve cells that coordinates and controls the different
activities of the body 4. The control center of the nervous system
5. The part where messages travel to and from the brain 6. A
network of nerve cells 7. These are certain membranes which protect
the brain and spinal cord 8. Speeds up the heartbeat when the body
is active or under emotional stress 9. Controls involuntary
movements of some body organs such as the heart 10. Part of the
autonomic nervous system which slows down bodily funcions
16. THE BRAIN Lesson 2
17. Did you know that people in the ancient times thought that
thinking was done in the heart? Scientists know now that the brain
is the master control unit for the body. The brain is a soft
three-pound mass of spongy tissue. When you were born, your brain
weighed less than one pound but when you were six years old, it had
already reached its full weight of about 3 pounds.
18. Does the weight of the brain of a man differ from a womans?
The average weight of a mans brain is about 1,360 grams while in
women, it is 1,250 grams. How much heavier is a mans brain from a
womans brain? The weight of the brain does not necessarily indicate
the state of ones mental development. Some famous personalities
have had brains weighing less than the average. A person with a
small head but well-developed brain cells may possess far more
intelligence than a person with a large head and a heavy
brain.
19. The brain is the largest and most complex part of the
nervous system. It consists of the cerebrum, cerebellum, and the
brainstem. The brainstem is divided into three parts: the medulla
oblongata, the midbrain and the pons.
20. The brain is the control center of the body. It receives
information about the outside world from your senses and sends out
messages to tell your body what to do. You use your brain to think,
learn, remember, hear, see, smell, taste, feel and think.
21. During a 70-year lifetime, a persons memory stores at least
100 trillion bits of information. That is as many bits as 500,000
copies of encyclopedia and more than 500 times the number of stars
in the Milky Way Galaxy. The brain also enables you to do
intelligent interpretations. It controls every activity in the body
such as breathing, moving the muscles, heartbeat and blood
pressure. Furthermore, the brain controls our emotions and
feelings.
22. The brain has three main parts- the cerebrum, the
cerebellum and the brainstem.
23. CEREBRUM The cerebrum is the largest and uppermost part of
the brain. It is about four-fifths of the total weight of that
organ. The surface of the cerebrum looks like the wrinkled walnut
with many grooves. The cerebrum has special areas to receive
messages about sight, hearing, smell, taste and touch. Other areas
control movement, personality and intelligence.
24. CEREBRUM The cerebrum enables you to think, memorize,
recognize and be aware of the things happening in your
surroundings. It receives and interprets the messages of the five
senses.
25. CEREBRUM The cerebrum is divided into two hemispheres.
Theses are the left hemisphere and the right hemisphere. The
hemispheres control opposite sides of the body. The right
hemisphere of the brain controls the muscles of the left side of
the body. The left hemisphere of the brain controls the muscles of
the right side of the body. The right hemisphere is specialized for
spatial relationship, imagination, insight and appreciation of art
and music. The left hemisphere is specialized for scientific
skills, numeracy skills, written and spoken language and analytic
thought.
26. CEREBELLUM The cerebellum is the second largest part of the
brain. It is under and behind the cerebellum. It coordinates
movement of the muscles so that walking is smooth and balanced. It
also maintains posture. It your cerebellum is damaged, you may be
paralyzed. You cannot move your arms and legs.
27. BRAINSTEM The brainstem is at the base of the brain. It
consists of the medulla oblongata, the midbrain and the pons. The
brainstem controls the involuntary actions such as heartbeat and
breathing. It conveys messages between the spinal cord and the
brain. It also takes care of reflex actions such as coughing and
blinking. Reflexes are automatic responses made by the body.
28. Sometimes, you do not notice many of the sounds, sights and
smells around you. If you stop and think, what you hear, see,
smell, touch and taste tells you much about your environment. Your
senses- your ears, eyes, nose, tongue and skin gather information
all the time. They send this information to your brain. But if you
are busy with other things, you might not notice what your senses
tell you.
29. You notice the things around you with your sense organs.
Each organ has special nerve cells. These nerve cells gather
information from your surroundings. Nerve cells in your ears gather
information about sound and send the message to the center of
hearing in the brain though the auditory nerves. Nerve cells in the
eyes gather information about sight and send this information to be
interpreted in the center of seeing in the brain through the optic
nerves. The different kinds of nerve cells in your skin gather
information about pressure, heat, cold and pain. The nerve cells of
your nose gather information about what you smell and send the
sensation to the center of smell in the brain through the olfactory
nerves. What do your nerve cells in the tongue gather?
30. MEDULLA OBLONGATA This is the part of the brainstem located
at the very base of the brain. It is about 2.5 centimeters long and
one centimeter thick. It is a crossing place for nerve fibers
connecting the other parts of the brain with the spinal cord.
31. MIDBRAIN The midbrain lies between the cerebrum and the
cerebellum. It serves as a pathway for nerve fibers leading to and
from various areas of the brain and spinal cord.
32. PONS Pons is a thick tract of nerve fibers in the brain
that links the medulla oblongata to the brain. The pons is named
after its discoverer, the Italian anatomist C. Varoli
(1543-75).
33. REMEMBERING SCIENCE FACTS The brain is the control center
of the body. The main parts of the brain are the cerebrum,
cerebellum and brainstem. Cerebrum controls thought and actions.
Cerebrum coordinates movements of the muscles. Brainstem controls
involuntary actions. The main parts of the brainstem are the
medulla oblongata, midbrain and pons. The brain gets information
from the surrounding through the nerve cells in the different sense
organs.
34. REACHING OUT: SUPPLY THE MISSING WORDS Brain is divided
mainly into __________, __________, and __________. Cerebrum
controls thoughts and __________. ___________ coordinates movements
of the muscles. ____________ controls involuntary actions. The
brainstem is divided into __________, __________, and pons.
____________ regulates reflex responses controlling the heartbeat,
breathing, etc. Midbrain controls movement of the eyes. Pons relays
impulses between different parts of the ___________.
35. THE NERVES Lesson 3
36. The basic unit of the nervous system is the neuron. It is
commonly called a nerve cell. These nerve cells or neurons are
elongated branched cells. They looks like twigs of a branch of a
tree. There are about 100 billion nerve cells in your body.
37. Neurons carry messages from one part of your body to
another. These messages of sensation and information are called
impulses. These nerve impulses that travel along a neuron are
similar to a tiny electrical charge. Nerve impulses can travel as
fast as 360 feet per second along an axon. An axon is a long fiber
that carries impulses away from the cell body to other neurons. At
that speed, an impulse could cover the length of a football field
in less than one second.
38. Does a neuron have parts? What is the function of each
part? The neuron in your brain consists of the cell body, the axons
and the dendrites.
39. CELL BODY Each neuron has a cell body with nerve fibers
consisting of one axon and one or more dendrites. A cell body
contains the nucleus. It varies in shape. It may be round, oval,
star- shaped or pyramidal.
40. AXONS An axon is a long nerve fiber that extends from the
body cell. It may extend for a distance of only a few centimeters
or one meter for it may run all the way from the spinal cord to the
tip of a toe or finger. It is less than 0.01 millimeters in
diameter. Axons carry nerve impulses away from the cell body to
other neurons.
41. DENDRITES The dendrites are nerve fibers like tiny trees
that receive impulses and send them to the cell body. They are
microscopic. These are short and often branch repeatedly so they
form a sort of bush around the cell body. Because dendrites have so
many branches, one neuron can receive messages from hundreds of
other neurons.
42. SYNAPSE Synapse is a space between the end of the axon of
one neuron and the dendrite of another. Synapses control the
overloading of messages sent to the brain. As an impulse reaches
the end of an axon, it is passes to a dendrite of the next neuron
by neurotransmitters. Neurotransmitters are chemicals that pass
across a synapse from an axon to a dendrite. This chemical is
released into that tiny space and received by the receiving
neuron.
43. KINDS OF NEURONS There are three kinds of neurons according
to the direction of the nerve impulse being transmitted. These are
the sensory neurons, interneurons and motor neurons.
44. SENSORY NEURONS OR AFFERENT Sensory neurons transmit
impulses from the sense organs, the skin, the muscles and internal
organs to the spinal cord or brain. For example, when you touch an
ice cube, the neurons that sense cold send this message to your
brain. Afferent is derived from a Latin word afferie which means to
carry to or in.
45. MOTOR NEURONS OR EFFERENT Motor neurons transmit impulses
from the interneurons to the muscles, glands and internal organs of
the body. Every movement of the body, such as the blinking of your
eyes, is controlled by messages carried by motor neurons to the
muscles. In the example of the ice cube, the message being carried
by the motor neurons might be to stimulate the hands muscles to
pick up the ice cube and place it in a glass. Efferent came from
the word efferre, meaning to carry out or away.
46. INTERNEURONS Interneurons transmit impulses from sensory to
motor neurons and process incoming information.
47. REMEMBERING SCIENCE FACTS The principal parts of a neuron
are dendrites, body cell and axons. The nerve cells or neurons
carry nerve impulses from one part of the body to another. Cell
body contains the nucleus. Axons carry impulses away from the cell
body to other neurons. Dendrites receive impulses and send them out
to the cell body.
48. REACHING OUT: TRUE OR FALSE 1. The nerve cells carry nerve
impulses from one part of the body to another. 2. Axons receive
impulses and send them to the cell body. 3. Body cells are thick
nerve fibers. 4. Dendrites carry nerve impulses toward the body
cells. 5. Afferent neurons carry impulses from sense organs to the
brain. 6. Synapses control the overloading of messages sent to the
brain. 7. Efferent or motor neurons transmit impurities from the
sense organs to the brain. 8. A cell body contains the nucleus. 9.
The neurons in the brain consist of the cell body , the axons and
the dendrites. 10. An axon is a nerve fiber that looks like a tiny
tree.
49. THE SPINAL CORD Lesson 4
50. Where is your spinal cord located? What is the importance
of the spinal cord in your body? Move your hand at the back of your
neck downward. What can you feel? This is your backbone or spine.
Your backbone protects your spinal cord.
51. The spinal cord is a dense bundle of nerves that runs down
the middle of the spine from the brain. Nerves in the spinal cord
branch out and connect your brain with nerves in your body. Its
average length is about 42 centimeters in the adult female and 45
centimeters in the adult male. Get a tape measurer or a ruler then
find 42 and 45 centimeters. The spinal cord is about 2% of the
weight of the central nervous system. What does the spinal cord
do?
52. FUNCTION OF THE SPINAL CORD The spinal cord is an extension
of the brain. Messages from the different parts of the body travel
through it to the brain and back. The nerves in the spinal cord
carry these messages to and from your brain.
53. The spinal cord enables us to do things automatically. This
automatic action is called a reflex action. For instance, when you
touch a hot object such as a flat iron, you immediately withdraw
your hand. This action does not involve your brain because you do
not think at all whether you avoid the hot object or not.
54. In a reflex action, the nerve impulses take on a special
pathway called a reflex arc. In the case of your touching the iron,
the impulse moved from the skin where it came in contact with the
flat iron along a sensory nerve to your spinal cord. Here the
impulse set off another impulse in a motor nerve running from your
spinal cord to your arm muscles. The muscles contracted and pulled
your hand away from the flat iron. This action took place in less
than 1/50 of a second. At the same time, the original impulse
traveled up your spinal cord to your brain, where you felt it as
pain.
55. A reflex is a rapid automatic response to the environment
that happens without action from the brain. Reflexes can be a
movement, as in motor reflex. Blinking when something comes to
close to the eyes is a motor reflex.
56. Other kinds of reflex action can develop through memory.
The brain remembers how to respond to certain signals or
situations. This is called conditioned reflex. A conditioned reflex
is based, in part at least, upon previous experience. For example,
hearing an ice cream van might make someones mouth water. This is a
conditioned reflex.
57. Another example is seeing and smelling food you like most.
Before you actually put food in your mouth, you see it and smell
it. You associate its appearance and odor with its taste. As a
result, when you see and smell foods that you like, even though you
do not actually taste it, saliva is secreted and your mouth will
water. In this case, the secretion represents a conditioned reflex.
Conditioned reflexes vary from one individual to another.
58. Reflex actions are very useful. They protect you from harm.
Blinking is a reflex that helps protect your eyes from objects
flying through the air toward your face. Sneezing and coughing are
reflexes that help to remove objects from your throat and air
passages. If you have to think about what movements to make when
suddenly threatened with harm, you might become confused and do the
wrong thing. The automatic action of your reflexes usually causes
you to act correctly and quickly enough to avoid the danger
threatening you.
59. REMEMBERING SCIENCE FACTS The spinal cord enables us to do
things automatically. It is a channel through which messages travel
from the different parts of the body to the brain and back. A
reflex action is an automatic action or response made by your body.
It can be a motor reflex or conditioned reflex.
60. REACHING OUT: TRUE OR FALSE 1. The spinal cord is a bundle
of nerves that runs down the middle o the spine from the brain. 2.
The spinal cord prevents us from doing things automatically. 3. The
spinal cord is protected by the skull. 4. The spinal cord transfers
messages between the different parts of the body and the brain. 5.
The spinal cord is responsible for reflex actions. 6. A reflex
happens automatically without action from the brain. 7. A motor
reflex is based upon previous experience. 8. The spinal cord is an
extension of the brain. 9. Reflex actions protect you from harm.
10. Conditioned reflexes remain the same from one person to
another.
61. COMMON AILMENTS OF THE NERVOUS SYSTEM Lesson 5
62. You have learned that the nervous system is very important.
It does several things that are important to your life. But there
are some ailments that may prevent it from doing one or more of
those things. How do you know that a person has a disorder of the
nervous system?
63. Some signs of a nervous system disorder may include
numbness in the limbs, pain or slurred speech. However, these
symptoms may be caused by other body ailments. The diseases
affecting the brain, nerves of the body and spinal cord form the
subject matter of the branch of medicine called neurology. Some of
the ailments affecting the brain, the spinal cord and the nerves
are the following:
64. EPILEPSY Epilepsy is a disorder of the brain. People who
suffer from epilepsy have regular convulsions. Epilepsy may affect
part or all of the brain. It is caused by a surge of electrical
activity in the brain. There are three main kinds of epilepsy. In
one kind, a person may suddenly fall to the ground or floor. His
body may move without his control. The persons mind may go blank
during this time. In a second kind, a person may stop what he is
doing and stare into space for a few seconds. In a third kind, a
person may be doing something and suddenly forget what he is doing
even though he may keep on doing it.
65. MENINGITIS Meningitis is an inflammation of the covering of
the brain and the spinal cord. It is caused by a virus or bacteria.
It can cause death.
66. CEREBRAL PALSY This disorder is caused by damage to the
brain. Sometimes, this is caused by premature birth. Sometimes it
may happen when a person damages his brain in some kind of
accident. Some people with cerebral palsy have problems in
speaking, hearing or seeing. Such problems are caused by damage to
the part of the brain that controls speaking, hearing or seeing.
The sufferer can be helped by speech therapy, physical therapy, and
surgery to correct muscles.
67. BRAIN TUMOR A person suffering from a brain tumor feels
severe headache. As the tumor grows, it presses in the nerve cells
causing intense pain. It can be removed by operation if it is
detected early.
68. POLIO Polio is caused by a viral infection which destroys
the motor nerves in the spinal cord. This is manifested by fever,
headache, muscle ache, runny nose and paralysis. The best way to
control polio is immunization. Children are given anti- polio
vaccines so that they will not be infected with polio.
69. ENCEPHALITIS This is a germ- caused disorder of the nervous
system. Sometimes it is called sleeping sickness because it may
cause a person to be very sleepy or drowsy all the time.
70. Accidents can also cause damage to the brain, spinal cord
and the nerves. The brain may be injured when there is a heavy blow
on the head. Injury to the brain may cause internal bleeding.
71. PARALYSIS Paralysis is a loss of the ability to move a part
of the body due to nerve or muscle damage. An injury to the spinal
cord may cause permanent paralysis. It may affect one little muscle
or most of the body. Quadriplegia is the paralysis of the body from
the neck down. Paraplegia is the paralysis of the lower body and
legs.
72. REMEMBERING SCIENCE FACTS Some of the common ailments of
the nervous system are meningitis, cerebral palsy, polio,
encephalitis, epilepsy and brain tumor.
73. REACHING OUT: MATCHING 1. An inflammation of the covering
of the brain and spinal cord 2. Caused by premature birth 3. A
germ-caused disorder which may cause a person to be sleepy all the
time 4. Caused by a viral infection which destroys the motor nerves
in the spinal cord 5. Condition manifested by convulsions a.Brain
tumor b.Cerebral palsy c.Encephalitis d.Epilepsy e.Meningitis f.
Polio
74. REACHING OUT: TRUE OR FALSE 1. A person suffering from a
brain tumor feels severe headache. 2. Cerebral palsy is caused by a
surge of electrical activity in the brain. 3. Accidents can cause
damage to the nervous system. 4. An injury to the spinal cord may
cause permanent paralysis. 5. Polio is also called sleeping
sickness.
75. KEEPING THE NERVOUS SYSTEM HEALTHY Lesson6
76. Why do people wear helmets in a construction site? Why does
the government require the use of seatbelts? Here are some ways to
keep your nervous system healthy:
77. 1. Avoid accidents or injuries that may damage your brain
or spinal cord. Wear a helmet when playing football and while
riding a bicycle or motor bike. Wear a seatbelt when riding in a
car.
78. 2. Watch out for falling debris or objects when passing
along a construction site.
79. 3. Cross only on the pedestrian lane. Be sure vehicles are
at a stop before crossing the street.
80. 4. Keep the stairs free from things which can cause you to
fall. Avoid putting slippery doormats on the door or near the
stairs.
81. 5. Avoid alcoholic drinks. Alcohol changes the way you
feel, see, hear, think and act. If not avoided, drink
moderately.
82. 6. Avoid smoking. Smoking destroys the nerve endings in the
nose and tongue.
83. 7. Free your mind of worries and anxieties to make it a
reliable and efficient leader of your body.
84. 8. Stay away from drugs. Drugs contain harmful substances
that can affect your nervous system.
85. 9. Relax your nerves and spend your leisure time
wisely.
86. 10. Eat plenty of vegetables and fruit.
87. 11. Take vaccines such as the anti-polio vaccine to keep
from getting infections of the nervous system.
88. REMEMBERING SCIENCE FACTS Proper care and protection should
be given to our nervous systems.
89. REACHING OUT: YES OR NO IS THIS A PROPER WAY TO CARE FOR
THE NERVOUS SYSTEM? 1. Keep the stairs free from scattered toys. 2.
Use slippery doormats. 3. Avoid worries and anxieties. 4. Walk on
the pedestrian lane. 5. Drink alcohol. 6. Keep yourself safe from
accidents. 7. Eat plenty of fruits and vegetables. 8. Take drugs.
9. Wear a helmet when riding on a motorcycle. 10. Use a
seatbelt.
90. FOR YOU TO REMEMBER The two main parts of the nervous
system are the central nervous system and peripheral nervous
system. The central nervous system consists of the brain and the
spinal cord. The CNS stores and processes information and sends
information to muscles and glands. The peripheral nervous system
consists of the nerves that are linked with the central nervous
system and their motor and nerve endings. It carries messages to
and from the central nervous system. The autonomic nervous system
controls involuntary action. The nervous system is the bodys
communication network.
91. The brain is the control center of the body. The main parts
of the brain are the cerebrum, cerebellum and brainstem. Cerebrum
controls thought and actions. Cerebrum coordinates movements of the
muscles. Brainstem controls involuntary actions. The main parts of
the brainstem are the medulla oblongata, midbrain and pons. The
brain gets information from the surrounding through the nerve cells
in the different sense organs.
92. The principal parts of a neuron are dendrites, body cell
and axons. The nerve cells or neurons carry nerve impulses from one
part of the body to another. Cell body contains the nucleus. Axons
carry impulses away from the cell body to other neurons. Dendrites
receive impulses and send them out to the cell body. The spinal
cord enables us to do things automatically. It is a channel through
which messages travel from the different parts of the body to the
brain and back. A reflex action is an automatic action or response
made by your body. It can be a motor reflex or conditioned
reflex.
93. Some of the common ailments of the nervous system are
meningitis, cerebral palsy, polio, encephalitis, epilepsy and brain
tumor. Proper care and protection should be given to our nervous
systems.