Nervous System. from the Human Body Systems Series. catalog # Published & Distributed by AGC/UNITED LEARNING

Transcription

1 Nervous System from the Human Body Systems Series catalog # 2890 Published & Distributed by AGC/UNITED LEARNING 1560 Sherman Avenue Suite 100 Evanston, IL Hour Fax No Website: info@agcunited.com 1

2 THE NERVOUS SYSTEM Grade Levels: 6-9 (Review for Grades 10-12) Viewing Time: 20 minutes with video quiz INTRODUCTION This video is designed for use in grades 6-9 as an introduction to the major ideas and concepts associated with the human nervous system, and for use in grades as review. PROGRAM OBJECTIVES After viewing the video and participating in the accompanying activities, the students will be able to Describe the function and workings of the nervous system. Identify the main parts of the nervous system. Identify the way the nervous system works to regulate various body activities. Define key vocabulary terms associated with the nervous system. SUMMARY OF THE VIDEO This video describes the functions of the nervous system. The nervous system monitors and maintains all body functions, and at the same time, interprets information about our surroundings supplied by the senses. The brain, which is the most important part of the nervous system, has often been compared to a computer. This is an unfair comparison because a computer could never come close to performing the kinds of sophisticated analysis and decision making that the human brain engages in at any given moment. 2

3 INSTRUCTIONAL NOTES Before presenting this lesson to your students, we suggest that you preview the video and review this guide and the accompanying blackline master activities in order to familiarize yourself with their content. As you review the materials presented in this guide, you may find it necessary to make some changes, additions, or deletions to meet the specific needs of your class. We encourage you to do so, for only by tailoring this program to your class will they obtain the maximum instructional benefits afforded by the materials. It is also suggested that the video presentation take place before the entire group under your supervision. The lesson activities grow out of the context of the video; therefore, the presentation should be a common experience for all students. TEACHER PREPARATION View the video and review the accompanying activities. Duplicate any blackline masters you wish to distribute. If you plan to use the Blackline Master 1, Video Quiz, which immediately follows the video presentation, you may wish to have copies of the quiz ready to distribute at the completion of the video program. Also, plan to pause the tape between questions if students require more time. INTRODUCING THE VIDEO Ask students to think about all the things happening with their bodies at this very instant. Food may be digesting, blood is circulating, lungs are exchanging gases, the heart is pumping, and the brain is thinking. Information is streaming into the brain about the conditions of the body and the surrounding environment. The system responsible for monitoring all this information and keeping things working properly is the nervous system. 3

4 Present the video. the viewing time is 17 minutes for the program and about 5 minutes for the Video Quiz. BLACKLINE MASTER DESCRIPTIONS Most of the follow-up activities for this program are designed for middle school grades. If you use this program with an older audience, you will need to adapt the materials appropriately. Blackline Master 1, Video Quiz is to be used at the end of the video program. At the completion of the video, there is a short quiz. The narrator will read the questions which are displayed on the screen. Students can use this sheet to record their answers. Answers to the questions are provided in the Answer Key found on page 5. Blackline Master 2, Vocabulary, is a collection of important vocabulary words from the video. You may want to distribute this sheet before viewing the video so students can listen for definitions. Blackline Master 3, Stimulus-Response Time is an experiment to test response time for visual, auditory, and tactile stimulus. Students should work in pairs. Blackline Master 4, The Mobius Strip, is an experiment that illustrates that some things are difficult to explain because the part of our brain that understands shapes and patterns doesn t control speech. Blackline Master 5, Quiz, is the formal test for this unit of study. INTERNET ACTIVITIES Neuroscience for Kids Everything you need to connect to all kinds of resources and information on the nervous system. 4

5 BRAIN SURF Introuduces the general public to the field of neuroscience. BRAIN COLLECTION Collection at the University of Wisconsin of brains of many animals. DISCUSSION QUESTIONS 1. Discuss the difference between voluntary action and reflex action. 2. Have the class consider what it would be like if we had to consciously think about everything that is happening with our bodies. Imagine having to think about breathing or circulating blood. ENRICHMENT ACTIVITIES 1. Scientists have found that the brain produces its own painkillers called endorphins. Students could use the library to find out more about these natural painkillers. 2. One of the most important sources of information for the nervous system comes from the skin. There are hundreds of thousands of various sensors in the skin that send data to the brain. For instance, take a pencil and touch the tip on the back of the hand. Some places touched will feel cold because there are hot, cold, and pressure sensors throughout the area. 5

6 ANSWER KEY Blackline Master 1, Video Quiz 1. The central nervous system is made up of the brain and the spinal cord. 2. The peripheral nervous system is made up of all the nerves that branch out from the brain and spinal cord and connect to sense and internal organs. 3. A voluntary action is accomplished when we conscious think about doing something, such as raise an arm or lift our foot. 4. Actions that are controlled by the autonomic nervous system are such things as the beating of our heart. 5. A neuron is the path along which electric and chemical impulses travel to the brain. 6. The three kinds of neurons are sensory, interneurons, and mo tor. 7. The synapse is the gap between neurons. 8. Nerve impulses are electrical when traveling through the neu ron; but when going across the synapse, the impulse changes to a chemical signal. 9. The five senses are sight, taste, smell, touch, and hearing. 10. A reflex action is in response to something harmful that must be immediately dealt with. It bypasses the normal route of sending a signal to the brain. Blackline Master 2, Vocabulary 1. central nervous system- the brain and spinal cord 2. peripheral nervous system - nerves that branch out from the brain and spinal cord and connect to sense and internal organs 3. autonomic nervous system- automatic actions such as breathing. 4. neuron - nerve path for impulses traveling to and from the brain 5. dendrite - part of the neuron which brings impulses to the cell body 6. axon- part of neuron which carries impulse away from cell body 6

7 7. myelin - covering on the axon which keeps the electrical impulse from traveling out of the axon 8. sensory neuron - collects signals from receptor cells and sends them to the brain or spinal cord 9. interneuron- connects sensory neurons and motor neurons 10.motor neuron - messages from the brain and spinal cord go to the motor neurons which are connected to muscle cells 11. synapse - gap between neurons 12. reflex action - bypasses normal paths to brain and goes to the spinal cord, where a decision is immediately made and a signal goes to the motor neuron to cause a quick reaction 13. eceptor cells - are sensor cells that send a signal to the sensory neuron 14. effector cells - cells in muscles that are stimulated by the motor neurons. Blackline Master 3, Stimulus-Response Time Answers will vary Blackline Master 4, Mobius Strip It is hard to describe how the Mobius Strip works because the right side of the brain, which recognizes shapes and patterns, doesn t control speech; and therefore, can t put it in words. Blackline Master 5, Quiz 1. The central nervous system is the brain and spinal cord. The peripheral nervous system is made up of all the nerves which branch out from the brain and spinal cord and connect to sense and internal organs. 2. The neuron is made up of a cell body, which is the control center; the dendrites, which surround the cell body and connect to other neurons; and the axon, which carries the impulse to the brain, spinal cord, or muscles. 3. The three kinds of neurons are sensory, interneurons, and motor. 4. The synapse is the gap between two neurons. The impulse travels as a chemical signal across the gap. 7

8 5. A reflex action is one that bypasses the normal path to the brain. Instead, the signal goes to the spinal cord, where a decision is made and an action is sent to the muscles. 6. The folds and grooves actually provide greater surface area. If the folds in the human brain were stretched out flat, it would cover an area that is one-half square yard. 7. Our bodies need sleep for rest, repair, and growth. 8. The computer can operate at fantastic speeds but never comes close to the capabilities of the brain. The brain can carry on creative thought. 9. The brain must have a constant supply of energy and oxygen. Every hour, about 33 quarts of blood circulate through the brain to keep it nourished. 10. The five senses are sight, touch, hearing, taste, and smell. SCRIPT OF VIDEO PRESENTATION THE HUMAN NERVOUS SYSTEM Every second of your life there are complex things happening within your body. Many of these things we take for granted, such as breathing, digesting food, circulating blood, or expelling wastes. The body is made up of organs that carry out various tasks that help maintain and sustain our bodies. The organs are organized into systems that carry out a particular task. The digestive system breaks down food into usable energy for the trillions of living cells in our bodies. The respiratory system gathers oxygen and then releases a waste product called carbon dioxide. The circulatory system is the transportation system that delivers the food and oxygen to all the cells and then returns the waste products for elimination from the body. 8

9 So at any given moment, many complex things are occurring that are all controlled by a single system called the nervous system. Whether we are juggling three tennis balls or just sitting and reading a good book, the nervous system is in control. It controls and monitors all body activities. It determines how to move and coordinate our muscles to keep the balls moving. It signals the eyes to scan the page and to adjust to allow the proper amount of light through the iris. The brain interprets the words and breaks them into ideas. At the same time, the brain is controlling the heartbeat, breathing rate, and receiving information about conditions around the body. The brain is the most important part of the nervous system. The nervous system is made up of two parts: the central nervous system and the peripheral nervous system. The central nervous system is composed of the brain and the spinal cord. The brain is responsible for interpreting all the information that is sent to it about what is happening inside and outside your body. It is the major control center for the entire body. Connected directly to the brain is the spinal cord that runs the entire length of your back. You can feel the bones called vertebrae that protect your spinal cord. The spinal cord is about 43 centimeters long and connects the brain to the rest of the nervous system through 31 pairs of nerves that branch out from the spinal cord. The spinal cord is about as thick as a pencil. The nerves that branch out from the spinal cord and others that branch directly from the brain go to all parts of the body. The nerves running from the brain are generally connected to sense organs and internal organs, such as the heart. The nerves branching out from the spinal cord are connected to the skeletal muscles. Many of the nerves in the peripheral nervous system respond to conscious thought. For instance, if you decide to raise your arm, a message travels from the brain to the spinal 9

10 cord and through the peripheral nerve to your arm. This is a voluntary action that is controlled by conscious thought. This is referred to as the somatic nervous system. There are other actions that are not voluntary or under conscious control. This part of the peripheral nervous system is called the autonomic nervous system, and includes such things as the heart beating. There are two kinds of autonomic nerves each affecting various organs of the body. These two kinds of nerves actually work opposite of each other to affect changes. For instance, if we sense danger, nerves connected to the heart and lungs will cause the organs to work harder. The heart beats faster and breathing rate is increased in case we need extra energy or strength. When the danger is over, other nerves slow the heart and lungs and bring us back to normal. The hundreds of messages that move throughout the nervous system every second travel along special cells called neurons or nerve cells. You are born with all the neurons you will ever have, for these special cells can not duplicate themselves like other body cells. Don t worry, there are more than enough neurons to last a lifetime. In fact, these cells die at the rate of thousands every day and yet this isn t a problem. The neurons are constantly making connections with other neurons to create paths for signals to travel along. An average neuron is connected to 50,000 other neurons and some are connected to 250,000. Neurons come in many sizes and shapes but contain the same basic structures. The largest part is the cell body, which contains the nucleus or control center of the cell. Branching off of the cell body are threadlike structures called dendrites. Dendrites carry messages to the cell body. The axon can be from one millimeter to more than a meter in length. At the end of the axon are axon terminals which collect information from receptor cells that monitor our surroundings. The axons might also pass messages on to other neurons. The messages travel as chemical and electrical signals. 10

11 The amount of electrical charge used by the brain and nervous system could almost light a flashlight bulb. The signals can travel as fast as 120 meters or 400 feet per second. The myelin covering helps to keep the electrical charge from traveling out of the axon. The thicker the axon and the myelin covering, the faster the electrical transfer. There are three types of neurons: sensory neurons, interneurons, and motor neurons. Sensory neurons collect a signal from the receptor cells located near their axon terminals. The messages travel through the sensory neurons to the spinal cord or brain. The spinal cord and brain contain interneurons, which connect the sensory neurons and the motor neurons. Messages from the brain and spinal cord travel to muscle cells through the motor neurons. The muscle cells that are stimulated by the motor neuron are called effectors. Neurons don t touch each other. There is a gap between them. This gap is called a synapse. The nerve impulse that travels as an electric charge through the nerve changes to a chemical signal when it nears the synapse. Then, the chemical signal moves across the gap and triggers an electric signal in the next neuron, and the signal continues on until it reaches its destination. So every second our brain is flooded with signals from all parts of the body. The information is sorted and interpreted and then decisions are made and signals are sent to muscle and gland cells for action. Sometimes things happen very quickly and it s necessary for immediate action. In cases like these, reflexes jump into action. A reflex action bypasses the normal paths from sensory neurons to interneurons to the brain and then out to motor neurons. Instead, 11

12 the sensory signal goes to the spinal cord where it is determined immediate reaction is required and a signal goes to motor neurons for quick action. Reflex actions are designed to protect our bodies from immediate danger. It is an emergency reflex. An example is when we touch something hot. The receptor cells for touch and heat in our fingers sense the heat and send a signal to the spinal cord, which then sends a signal to the muscles in our arm, which quickly pull our hand out of the way. In this way, valuable time is saved. The brain becomes aware of the situation, but after it has taken place. There are five senses that supply our brain with information about our surroundings. The senses of touch, taste, smell, hearing, and sight constantly send signals to the brain for interpretation. The sense of sight is responsible for the greatest amount of information. It is believed that the brain ignores about 95 to 99% of all the information sent to it from all the sense organs. The brain is the most important part of our bodies. It is well protected by the bony skull and three layers of membranes. The outer layer is a thick, tough membrane that makes contact with the inside of the skull. The middle layer contains a watery fluid, which helps to cushion the brain during sudden impacts. The inner layer clings to the brain and is made up of connective tissue. The brain has been described as an oversized walnut. The cerebrum is the largest part of the brain. The deep grooves increase the surface area of the cerebrum. If the surface were unfolded, it would equal an area the size of this fabric. This is the area where voluntary activities, intelligence, learning, and judgment occur. It is where attitudes, emotions, and personality are formed. The cerebrum is divided into two halves. The right half controls the left side of the body and the left half of the brain controls the right side of the body. Also, the right half is where artistic ability is found and the left half is where mathematical ability is located. 12

13 The right brain is good at creative thinking, recognizing shapes, and working with music and art. The left brain is good at logical thinking and is used for speech and writing. The outside of the cerebrum is covered by the cerebral cortex which is often referred to as the gray matter. The cortex is divided into four lobes. The frontal lobe is for thinking and creating. The parietal lobe helps us recognize objects and to find our way. The temporal lobe helps us hear, speak, and remember. The occipital lobe is where information from the eyes are turned into pictures. Scientists have mapped the brain and determined the location for various functions. The next largest part of the brain, the cerebellum, is responsible for maintaining our bodies balance and muscle coordination. Cats have a large cerebellum, which provides them with excellent balance. The medulla is the part of the brain that connects to the spinal cord. It controls involuntary actions, such as our heartbeat, blood pressure, and breathing rate. The midbrain has nerves that control the muscles that move and control our eyes. The pons regulates our waking and sleeping. Messages from the senses travel through the thalamus on the way to other parts of the brain. If the body must quickly react to pain, the thalamus acts as the trigger. The hypothalamus regulates our body temperature and indicates when we need food and drink. The limbic system helps us experience emotions and is important in memory. 13

14 Our bodies need sleep to stay healthy. It is during sleep that the body grows. That s why babies require so much sleep. Their bodies are going through a growth spurt. Humans spend about a third of their lives sleeping. During sleep the brain is still active. The parts that control voluntary movements are resting. However, other parts of the brain are still active. About one- fourth of the night is spent dreaming. Dreaming may be a way for the brain to sort out the day s activities. The brain is so important that if there is a lack of food or water, the rest of the body will go hungry to allow the brain to continue functioning. The human brain, at two to three pounds, is about 2% of the body weight. Yet, the brain uses about 20% of our bodies energy. Every hour about 33 quarts of blood travels through the brain to nourish it and keep it healthy. It is thought that everything we experience is retained as memory. Memories are stored when neurons make new connections with other neurons in the brain. Memories that are either very pleasant or very unpleasant seem to stick with us better. Scientists believe there are two kinds of memory: short-term and long-term. Short-term memory stores things that have happened within the past few minutes or hours. You may look up a telephone number and need to remember it just long enough to dial it. Much of the short-term memory is then forgotten. When something is more important, it may be stored in long-term memory, so the telephone numbers of friends are kept in memory. The brain is only about as big as your two fists held together, but it is capable of storing huge amounts of information. Sometimes we remember things without any effort and other times we may practice over and over to remember something or learn to do something. 14

15 Study these objects for sixty seconds. Now, pause the tape and write down the names of as many objects as you can remember from the group just shown. Before turning the video back on, compare your results. Did you see the motorcycle, four-by-four truck, stool, chair, office desk, file cabinet, hammer, plant, red lamp, fork, green crayon, toothbrush, calculator, teapot, battery, kitchen cleaner, and clock? Our brains have been compared to computers. But this is not a fair comparison because a computer is only a very fast calculating tool. The human brain is capable of doing and storing so much more that it isn t a fair comparison. The human brain is so much more advanced. It is responsible for maintaining our bodies and collecting information about the body and its surroundings to make important decisions about how to keep the body safe and functioning. When someone is juggling, the brain is collecting information from the eyes and hands about speed and velocity and arch so that calculations can be made to adjust for the next throw or catch. At the same time all this is happening, the brain is monitoring the rest of the body and regulating the heartbeat, breathing rate, and maintaining our balance. There is no computer that can handle the kind of information input, interpretation, and decision making that occurs inside a human brain. This concludes the video presentation. A short quiz will follow. You may write answers on the Blackline Master entitled Video Quiz or on a separate sheet of paper. 1. What makes up the central nervous system? 2. What makes up the peripheral nervous system? 3. What is an example of a voluntary action? 4. What is an example of an action that is not voluntary or under conscious control? 5. What is a neuron? 15

16 6. What are the three kinds of neurons? 7. What is a synapse? 8. How do nerve impulses travel across the synapse? 9. What are the five senses? 10. What is a reflex action? 16