1. 1. THE NERVOUS SYSTEM Chapter 2
2. 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. 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. 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. 5. PARTS OF THE NERVOUS SYSTEM Lesson 1
6. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 16. THE BRAIN Lesson 2
17. 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. 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. 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. 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. 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. 22. The brain has three main parts- the cerebrum, the cerebellum and the brainstem.
23. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 35. THE NERVES Lesson 3
36. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 46. INTERNEURONS Interneurons transmit impulses from sensory to motor neurons and process incoming information.
47. 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. 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. 49. THE SPINAL CORD Lesson 4
50. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 61. COMMON AILMENTS OF THE NERVOUS SYSTEM Lesson 5
62. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 72. REMEMBERING SCIENCE FACTS Some of the common ailments of the nervous system are meningitis, cerebral palsy, polio, encephalitis, epilepsy and brain tumor.
73. 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. 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. 75. KEEPING THE NERVOUS SYSTEM HEALTHY Lesson6
76. 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. 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. 78. 2. Watch out for falling debris or objects when passing along a construction site.
79. 79. 3. Cross only on the pedestrian lane. Be sure vehicles are at a stop before crossing the street.
80. 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. 81. 5. Avoid alcoholic drinks. Alcohol changes the way you feel, see, hear, think and act. If not avoided, drink moderately.
82. 82. 6. Avoid smoking. Smoking destroys the nerve endings in the nose and tongue.
83. 83. 7. Free your mind of worries and anxieties to make it a reliable and efficient leader of your body.
84. 84. 8. Stay away from drugs. Drugs contain harmful substances that can affect your nervous system.
85. 85. 9. Relax your nerves and spend your leisure time wisely.
86. 86. 10. Eat plenty of vegetables and fruit.
87. 87. 11. Take vaccines such as the anti-polio vaccine to keep from getting infections of the nervous system.
88. 88. REMEMBERING SCIENCE FACTS Proper care and protection should be given to our nervous systems.
89. 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. 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. 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. 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. 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.