14. The process of occurs when a released egg cell has not been fertilized. A menstruation C pregnancy. 15. Perspiration leaves the body through the

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1 14. The process of occurs when a released egg cell has not been fertilized. A menstruation C pregnancy B ovulation D mitosis 15. Perspiration leaves the body through the A kidneys C skin B lungs D feces 16. You get oxygen into your lungs when you A swallow C exhale B relax D inhale 17. Most digestion takes place in the. A esophagus C small intestine B stomach D large intestine 18. The of the heart forces blood to the rest of the body. A right ventricle C right atrium B left ventricle D left atrium Critical Thinking Write the answer to each of the following questions. 19. The statement "All arteries carry blood that is high in oxygen" is incorrect. Why? Write a statement that describes all arteries. 20. What are four waste products made by the body? Make sure you have the same number of answers on your paper as the number of items on the test. Meeting the Body's Basic Needs Chapter

2 Chapter The Body's Control Systems Your body systems work 24 hours a day, seven days a week to take care of the business of living. Together, the body systems handle a lot of jobs. They break down food to supply energy for every cell. They also bring in oxygen and get rid of wastes. At the same time, the body systems make it possible for you to jog around the track, talk on the phone, or watch a movie. To carry out all of these functions, plus many more, the body systems must stay in touch with each other. In this chapter, you will learn how all of life's activities are coordinated. Organize Your Thoughts Systems that control the body's activities Nervous Coordinates ail body parts Endocrine Secretes hormones that change cell functions Goals for Learning To identify the structures and functions of the nervous system To explain how the sense organs function To identify the structures and functions of the endocrine system To explain what hormones are and what they do To explain changes that occur in puberty 57$

3 Lesson Objectives After reading this lesson, you should be able to + identify the structures and functions of the nervous system. ^ describe how impulses travel. ^ explain how the eyes "see" objects. + trace a sound wave as it travels through the ear. + describe how the senses of taste and smell work together. How the Nervous System Controls the Body Your body systems constantly work together to keep you healthy and functioning. For your systems to work, however, they have to be coordinated. All the different parts have to know what to do and when to do it. Your body has to respond to changes in the environment. For example, if you run, the heart has to know to pump faster. Your nervous system coordinates all of your body parts. It is your body's communication network. The Nervous System The nervous system is divided into two main parts. The central nervous system is made of the brain and the spinal cord. This system controls the activities of the body. The peripheral nervous system is made of nerves outside the central nervous system. This system carries messages between the central nervous system and other parts of the body. Brain Spinal cord Peripheral nerves The Central and Peripheral Nervous Systems The Hody's Control Systems ('hapter

4 Cerebrum The largest part of the brain that controls thought, memory, learning, feeling, and body movement Cerebellum The part of the brain that controls balance Brain stem The part of the brain that controls automatic activities and connects the brain and the spinal cord The Brain The three parts of the brain are the cerebrum, the cerebellum, and the brain stem. The largest part is the cerebrum, as the diagram below shows. The cerebrum controls the way you think, learn, remember, and feel. It controls muscles that let you move body parts, such as your arms and legs. It interprets messages from the sense organs, such as the eyes and ears. The cerebrum is divided into two halves. The left half controls activities on the right side of the body. The right half controls activities on the left side of the body. The cerebellum lies beneath the cerebrum. The cerebellum controls balance. It helps muscles work together so that you walk and write smoothly. Under the cerebellum is the brain stem. It connects the brain and the spinal cord. The brain stem controls the automatic activities of your body. These include heart rate, gland secretions, digestion, Cerebrum respiration, and circulation. The brain stem coordinates movements of muscles that work without your thinking about them, such Brain stem as your stomach Cerebellum muscles. The Brain The Spinal Cord The spinal cord is a thick bunch of nerves that starts at the brain stem and goes down the back. The spinal cord is protected inside a backbone. The brain sends and receives information through the spinal cord. Thirty-one pairs of spinal nerves branch off from this cord. The spinal nerves send nerve messages all over the body. The spinal cord and brain are the central controls of the sense organs and body systems. 580 Unit 4 The Human Body

5 Neuron A nerve cell Impulse A message that travels along nerve cells Synapse A tiny gap between neurons Neurons Nerve cells are called neurons. They send messages in the form of electrical signals all through the body. These messages are called impulses. An impulse rapidly carries information from one nerve cell to the next. Neurons do not touch each other. Impulses must cross a small gap, or synapse, between neurons. This happens when an impulse travels from one end of a neuron to the other. When the impulse reaches the end of the cell, a chemical is released. The chemical moves out into the synapse and touches the next neuron. This starts another impulse. Information moves through your body by traveling along many neurons. There are three kinds of neurons in your nervous system. Sensory neurons carry impulses from sense organs to the spinal cord or the brain. Motor neurons carry impulses from the brain and spinal cord to Dendrites muscles and glands. Synapse Neuron Association neurons carry impulses from sensory neurons to motor neurons. Dendrites carry messages to the cell body. The axon carries messages away Neurons from the cell body. Reflex Actions Sneezing, coughing, and blinking are reflex actions. They happen automatically. What happens if you touch a hot frying pan? Sensory neurons send the "It is hot!" message to the spinal cord. Inside the spinal cord, association neurons receive the impulses and send them to the motor neurons. All of this happens in an instant, as you feel the heat. You pull your hand away quickly. You have been saved from a serious burn. Many other reflex actions protect the body from injury. For example, if an object comes flying toward your eyes, you blink without thinking. The Body's Control Systems Chapter

6 Receptor cell A cell that receives information about the environment ami starts nerve impulses to send that information to the brain Cornea A clear layer of the eye that light passes through Iris The part of the eye that controls the amount of light that enters Pupil The black circle in the center of the iris Retina The back part of the eye where light rays are focused Optic nerve A bundle of nerves that carry impulses from the eye to the brain The Sense Organs The body connects with the outside world through sense organs. The five main sense organs are the eyes, ears, skin, nose, and tongue. Your skin is the largest organ in your body. Receptor cells in these organs receive information about the outside world. Receptor cells send impulses to your brain through sensory neurons. Your brain makes sense of the impulses. Then you see, hear, feel, smell, and taste. The Sense of Sight Your eyes are your organs of sight. When you look at one of your eyes in a mirror, you see the white outer layer that protects your eye. The part of the outer layer of your eye that isn't white is a clear layer. Light enters the eye through this clear layer called the cornea. The colored part of your eye is the iris. It is made of tiny muscles arranged in a ring. The black circle in the center of the iris is an opening called the pupil. Light passes from the cornea through the pupil. The iris controls the amount of light that enters by making the pupil larger or smaller. The pupil opens wide in a dark room. The larger opening lets in more light, and you can see more clearly. Likewise, the pupil becomes smaller in bright sunlight. Find the cornea, iris, and pupil in the diagram of the eye. Then find the other parts of the eye as you read more about how the eye works. Optic nerve Retina Behind the pupil is a lens that focuses light. The lens focuses light rays onto the retina al the back of the eye. Receptor cells on the retina send impulses to a nerve bundle called the optic nerve. Nerve impulses travel along the optic nerve to the brain. The brain translates the impulses into images you can see. All of this happens faster than you can blink. 582 Unit 4 The Human Body

7 Eardrum A thin tissue in the middle ear that vibrates when sound waves strike it Cochlea The organ in the ear that sends impulses to the auditory nerve Auditory nerve A bundle of nerves that carry impulses from the ear to the brain The Sense of Hearing Just as your eyes collect light, your ears collect sound. Review the diagram below as you read about how the ears work. The outer ear acts like a funnel to collect sound waves. The waves travel through the ear canal to the middle ear. The middle ear, just behind the eardrum, contains three small bones. The eardrum is a thin tissue that vibrates, or shakes, when sound waves strike it. The sound waves then travel through each of the three bones. The sound waves enter the inner ear. They cause fluid in the cochlea to vibrate. The cochlea is a hollow coiled tube that contains fluid and thousands of receptor cells. These cells vibrate when sound waves strike them. The cells send impulses to the auditory nerve, which goes to the brain. The brain translates the impulses into sounds you can hear. Tiniest bones in the body Auditory nerve Outer ear Ear canal Cochlea Inner ear Eardrum Middle ear Hearing Aids Achievements In Science People who lose all or part of their hearing may choose to wear a hearing aid. A hearing aid is an object that makes sound louder. The earliest hearing aids were large, horn-shaped appliances that users held to ears. They simply tunneled sound waves into the ear canal. Today's hearing aids are smaller and more efficient. Most of them are made of the same basic parts. A microphone picks up sound and changes it into electrical signals. The signals are amplified, or made louder. A receiver changes these signals back into sound. Sound from the receiver is directed into the ear canal by an ear mold. A battery provides the power to operate the microphone, processor, and receiver. Some hearing aids are also made with volume control and other adjustments that help the wearer fine-tune it for their particular needs. The Body's Control Systems Chapter

8 The Sense of Touch The skin receives messages about heat, cold, pressure, and pain. Receptor cells in the skin send nerve impulses to the brain. Then you can tell if something is cold, hot, smooth, or rough. Your fingertips and lips are most sensitive to touch because they have the most receptor cells. The Senses of Taste and Smell Taste buds are tiny receptor cells on the tongue that distinguish four basic kinds of tastes. The four tastes are sweet, sour, bitter, and salty. Notice in the diagram that certain parts of the tongue are sensitive to each taste. The taste buds send impulses to the brain. The brain uses these impulses along with impulses from the nose and interprets Bitter them as tastes. Much of the sense of taste depends on the sense of smell. Receptor cells in the nose sense smells. If you hold your nose while you chew, much of your The Tongue sense of taste goes away. Why does this happen? As you chew and swallow, air carrying the smell of the food reaches the nose. When you hold your nose, the air cannot flow freely. The smells never reach the receptor cells in your nose. The brain doesn't have impulses from the nose to use with impulses from the tongue to interpret taste. Biometrics is a new type of technology that provides unique ways to identify human characteristics. There are a number of biometric technologies, including fingerprint identification, voice identification, and even body odor identification. One company is working on a product that can record your body odor. A sensor is used to "capture" your body odor from your hand. 584 Unit 4 The Human Body

9 Lesson 1 REVIEW Write your answers to these questions on a separate sheet of paper. Write complete sentences. 1. How is the central nervous system different from the peripheral nervous system? 2. Name the activities that each part of the brain controls. 3. How do impulses travel between neurons? 4. Name the three parts of the eye that light passes through in the order it travels from outside the eye to the retina. 5. Explain how holding your nose would affect how you taste food. Science in Your Life What can smart drugs do? You may have seen advertisements for "smart drugs" in stores, in magazines, or on the Internet. The drugs may be in the form of pills, drinks, or powders. They may be advertised as herbs, natural ingredients, nutritional supplements, or food additives. The ads might promise improved memory, more alertness, and better performance in school or on the job. But do smart drugs work? Smart drugs are supposed to work by increasing the amount of blood that flows to the brain. They may also increase the level of neurotransmitters involved in learning and memory. These ideas originated with research on people who had strokes and people who have Alzheimer's disease. People who had a stroke often suffer from memory loss. This is because the blood supply to some parts of the brain is reduced. In Alzheimer's disease, memory loss is due to destruction of neurons in the brain. Research on Alzheimer's continues. So far, a few drugs have been developed that may slow symptoms but can't cure the disease. Some drugs may help people with diseases affecting the brain. There are few scientific studies that have been done on healthy people. The studies that have been done provide conflicting information. Most scientists agree that, in healthy people, the brain receives enough blood. Many smart drugs have not been part of reliable scientific experiments. There is no evidence that these drugs will improve memory. Claims are usually false and do not mention possible side effects of using the drugs. Sorry, but taking a smart drug will not improve your memory or help you pass your next test. The Body's Control Systems Chapter

10 INVESTIGATION large index card pencil scissors + round, clear glass bowl + white tissue paper tape + large, round magnifying glass flashlight Modeling the Human Eye Purpose How do your eyes work? In this investigation, you will learn how parts of the eye work to focus an image. Procedure 1. Do this investigation with a partner. 2. Fold the index card in half lengthwise. On the fold, draw half of a shape that has a definite top and bottom for example, a valentine heart or a triangular pine tree. Cut out the shape and unfold the card. 3. Tape a sheet of white tissue paper to one side of the bowl. 4. Set up the magnifying glass near the other side of the bowl. Use clay to hold the magnifying glass up straight on the table. 5. Set up the opened card on the same side of the bowl as the magnifying glass but farther away from the bowl. Use clay to stand the card up straight. Your finished setup should look like the picture on the next page. 6. Darken the room as much as possible. Then shine the flashlight at the card so the light passes through the shape you cut out, the magnifying glass, and the bowl. 7. Look closely at the white paper. Move the bowl back and forth until the image is clear. What do you see? 586 Unit 4 The Human Body

11 Questions and Conclusions 1. What do you see on the white paper? How is the image different from the shape on the card? 2. In your model, what does the bowl represent? 3. What does the white paper represent? 4. What does the magnifying glass represent? Explore Further Move the bowl closer and farther from the lens. What happens to the image? The Body's Control Systems Chapter

12 How the Endocrine System Controls the Body Objectives After reading this lesson, you should be able to + explain what hormones do. ^ explain how a feedback loop works. + describe the stress response. + describe the changes that occur during puberty. Scientists have changed some bacteria so that they produce growth hormone. This hormone is used to treat children who do not produce enough of it themselves. The Endocrine Glands The endocrine system works closely with the nervous system to control certain body activities. Together the two systems respond to changes inside and outside the body. They adjust the body's activities to meet its needs. By doing so, they keep the body conditions within the range required for survival. The endocrine system is made of glands. Some of them are circled in the illustration on the next page. These glands secrete substances called hormones. Hormones are chemical messengers. Glands release hormones into the bloodstream. The hormones then travel all through the body. What Hormones Do There are more than 30 different hormones. They affect everything from kidney function to growth and development. Hormones work by attaching to certain cells. They change the function of the cells. Some examples of hormones are aldosteronc, insulin, and growth hormone. The adrenal glands secrete aldosterone. This hormone helps direct the kidneys to put more sodium and water back into the bloodstream. This may happen when a person has lost fluids. The pancreas secretes insulin, which changes cells so that glucose can enter them. The pituitary gland secretes growth hormone, which causes bones and muscles to grow. The Feedback Loop Glands must secrete the correct amounts of hormones for the body. The body has built-in systems that control the amount of hormone a gland releases. In one system, the feedback loop, a gland produces a hormone until levels of that hormone are high. Then production slows or stops. In another system, a change in the body triggers the release of a hormone. Eating a meal can alter hormone levels. These two mechanisms, plus the genes that direct the activities of cells, keep the human body operating correctly. 588 Unit 4 The Human Body

13 Adolescence The teenage years of a human Puberty The period of rapid growth and physical changes that occurs in males and females during early adolescence Adrenal glands Pineal gland Pituitary gland Thyroid and parathyroid Thymus Pancreas The pancreas is a part of both the endocrine system and the digestive system. As an endocrine gland, it releases the hormone insulin into the blood. As a gland of the digestive system, it secretes digestive enzymes into the small intestine. Hormones in the body are responsible only for regulating reproductive activity. Fact: There are more than 30 different hormones. Some hormones do regulate reproductive activity. But many other hormones control other activities in the body. Ovaries (females only) Testes (males only) Hormones and Stress Endocrine Glands When you feel scared or excited, your adrenal glands secrete a hormone called adrenaline. Adrenaline can trigger a stress response. It may cause your palms to sweat and your heart to speed up. If the stress response continues for a long time, it could have a negative effect on your body. At times, the stress response can be positive. Suppose you are running a race. The increase in your heart rate causes more oxygen to be delivered to your muscles. Adrenaline also increases the amount of glucose to your muscles. After the race, your body returns to normal. Hormones and Puberty The teenage years are called adolescence. At the beginning of adolescence, hormones cause rapid growth and physical changes. This period of growth and change is called puberty. During puberty in males, a boy's voice changes to a low pitch. Hair begins to grow on the face, under the arms, and in the area around the sex organs. The sex organs become more fully developed. During puberty in females, hair also begins to grow under the arms and around the sex organs. The breasts enlarge and menstruation begins. The Body's Control Systems Chapter

14 Lesson 2 REVIEW Write your answers to these questions on a separate sheet of paper. Write complete sentences. 1. What is the function of the endocrine system? 2. What are hormones? How do they affect the body? 3. How does the feedback loop work? 4. Give examples that show how the stress response can be positive and how it can be negative. 5. What are some changes that occur in males and females during puberty? T* AT* AT* AT* AT* AT* AT* AT* AT* AT* Science at Work Nurse A nurse needs good observation, decision-making, and communication skills. Nurses also need to keep accurate records, pay attention to detail, and perform medical tests and procedures carefully. The training for a nurse varies from about one year at a vocational school or a community college to four to five years at a university. All nurses must take and pass a state licensing exam. Nurses understand how all the human body systems work. They help people prevent disease and take care of people when they are sick, injured, or disabled. Nurses work i-n hospitals, doctors' offices, clinics, nursing homes, or other offices. The duties of a nurse include taking measurements such as blood pressure, giving injections, and monitoring. 590 Unit 4 The Human Body

15 Chapter 24 S U M M A The nervous system controls and coordinates all body activities. The nervous system has two main parts. They are the central nervous system and the peripheral nervous system. The brain and the spinal cord make up the central nervous system. The brain has three major parts the cerebrum, the cerebellum, and the brain stem. The three parts control different body activities. Impulses carry information from one nerve cell to the next. The five main sense organs are the eyes, ears, skin, nose, and tongue. Special cells in each of the sense organs receive information from the environment and send impulses to the brain. The glands of the endocrine system release hormones into the bloodstream. Hormones help control certain body activities. Hormones also cause the rapid growth and physical changes that occur during puberty. Science Words adolescence, 589 auditory nerve, 583 brain stem, 580 cerebellum, 580 cerebrum, 580 cochlea, 583 cornea, 582 eardrum, 583 impulse, 581 iris, 582 neuron, 581 optic nerve, 582 peristalsis, 553 puberty, 589 pupil, 582 receptor cell, 582 retina, 583 synapse, 581 The Body's Control Systems Chapter

16 Chapter 24 REVIEW \\onl Hunk adolescence cerebellum cornea impulse iris neuron puberty pupil synapse Vocabulary Review Choose a word from the Word Bank that best completes each sentence. Write the answer on a sheet of paper. 1. A nerve cell is called a(n). 2. is the period of rapid growth and physical changes during the early teen years. 3. The _. _ is the part of the brain that controls balance. 4. A is a tiny gap between neurons. 5. The teen years are known as. 6. The controls the amount of light that can enter the eye. 7. A message that travels from one neuron to another is a(n) 8. The black hole in the center of the iris is called the 9. A clear layer of tissue covering the front of the eye is the Concept Review Choose the answer that best completes each sentence. Write the letter of the answer on your paper. 10. The controls automatic activities such as digestion and circulation. A cerebrum C brain stem B cerebellum D spinal cord 11. Neurons send messages in the form of _ A visual C chemical B electrical D sound 12. protect the body from injury. A synapses C hormones B reflex actions D neurons signals. 592 Unit 4 The Human Body

17 13. Increased heart rate and breathing rate are signs of A reflex actions C associative neurons B the stress response D growth 14. The retina sends impulses to the nerve. A outer C motor B auditory D optic 15. The lens in the human eye focuses images on the. A pupil C cornea B retina D iris 16. The vibrates when sound waves strike it. A auditory nerve C ear canal B outer ear D eardrum 17. The organ in the ear that sends impulses to the auditory nerve is the. A eardrum C inner ear B cornea D cochlea 18. Insulin and adrenaline are examples of. A reflexes C receptor cells B glands D hormones Critical Thinking Write the answer to each of the following questions. 19. How are the "messengers" of the endocrine system different from those of the nervous system? 20. Why is it important for your brain to control many functions automatically? Make a labeled drawing to help you remember the names of the parts in a figure. The Body's Control Systems Chapter

18 UNIT 4 SUMMARY Bones support and protect the soft tissues and organs of the body. Skeletal muscles work in pairs to pull on bones. During digestion, food changes into a form that can enter cells. The large intestine eliminates undigested food. The circulatory system moves materials to and from cells. Red blood cells carry oxygen in hemoglobin. White blood cells protect the body from disease. Platelets help blood to clot. The respiratory system brings oxygen into your lungs and releases carbon dioxide from your lungs. The kidneys filter the blood to get rid of toxic wastes. The filtered wastes form urine. A male produces sperm cells. A female produces egg cells. When a sperm cell and an egg cell unite in fertilization, pregnancy occurs. 594 Unit 4 Summary

19 All body activities are controlled by the nervous system. The nervous system has two main parts: the central nervous system and the peripheral nervous system. The brain and spinal cord make up the central nervous system. The brain has three major parts the cerebrum, the cerebellum, and the brain stem. The three parts control different body activities. The five main sense organs are the eyes, ears, skin, nose, and tongue. Special cells in each of the sense organs gather information for the brain. The glands of the endocrine system release hormones into the blood. Hormones help control body activities. Summary Unit 4 595

20 UNIT 4 REVIEW Word Bank alveolus auditory nerve cardiac cerebellum eardrum epidermis glands hormones optic nerve perspiration pregnancy prostate gland Vocabulary Review Choose the word or words from the Word Bank that best complete each sentence. Write the answer on a sheet of paper. 1. is a liquid waste product released through the skin. 2. The term means "of the heart." 3. are chemicals that carry messages through the body. 4. A tiny sac-like structure in the lung is a(n). 5. A thin tissue that vibrates when struck by sound is the 6. is a period of time during which a fertilized egg develops into a baby. 7. The outermost layer of skin is called the. 8.. are structures in the body that release hormones. 9. The is the part of the brain that controls balance, 10. The is a bundle of nerves that carries impulses from the eye to the brain. 11. In the ear, nerves that carry impulses to the brain make up the 12. Fluid from the mixes with sperm to form semen. Concept Review Choose the answer that best completes each sentence. Write the letter of the answer on your paper. 1B. The supports the body and protects the internal organs. A excretory system C skeletal system B nervous system D digestive system 596 Unit 4 Review

21 14. The breaks down food for the body to use as fuel. A excretory system C skeletal system B respiratory system D digestive system 15. The is made up of the brain, spinal cord, and nerves. A excretory system C skeletal system B nervous system D digestive system 16. In males, the produce sex hormones that cause the growth of facial hair. A scrotum C cochlea B liver D testes 17. Most digestion takes place in the. A stomach C large intestine B small intestine D gallbladder 18. A bone is held to another bone by. A ligaments C muscles B villi D neurons Critical Thinking Write the answer to each of the following questions 19. How do the respiratory system, the digestive system, and the circulatory system work together? 20. Why is it important for your brain to control many functions automatically? Review Unit 4 597

22 Appendix A: Alternative Energy Sources Fossil Fuels We fly through the air in planes. We roll down highways in cars. On the coldest days, our homes are warm. Our stores are full of products to satisfy our needs and wants. The power that runs our lives comes from fossil fuels. A fossil is the remains of ancient life. Fossil fuels formed from the remains of dead matter animals and plants. Over millions of years, forests of plants died, fell, and became buried in the earth. Over time, the layers of ancient, dead matter changed. The carbon in the animals and plants turned into a material we now use as fuel. Fossil fuels include coal, oil, natural gas, and gasoline. Fossil fuels power our lives and our society. In the United States, electricity comes mainly from power plants that burn coal. Industries use electricity to run machines. In our homes, we use electricity to power lightbulbs, TVs, and everything else electric. Heat and hot water for many homes come from natural gas or oil, or from fuels that come from oil. Of course, cars and trucks run on gasoline, which is also made from oil. Powering our society with fossil fuels has made our lives more comfortable. Yet our need for fossil fuels has caused problems. Fossil fuels arc a nonrenewable source of energy. That means that there is a limited supply of these fuels. At some point, fossil fuels will become scarce. Their cost will increase. And one day the supply of fossil fuels will run out. We need to find ways now to depend less and less on fossil fuels. Fossil fuels cause pollution. The pollution comes from burning them. It is like the exhaust from a car. The pollution enters the air and causes disease. It harms the environment. One serious effect of burning fossil fuels is global warming. Carbon dioxide comes from the burning of fossil fuels. When a large amount of this gas enters the air, it warms the earth's climate. Scientists believe that warming ol the climate will cause serious problems. Renewable Energy Many people believe that we should use renewable fuels as sources of energy. Renewable fuels never run out. They last forever. What kinds of fuels last forever? The energy from the sun. The energy in the wind. The energy in oceans and rivers. We can use these forms of energy to power our lives. Then we will never run out of fuel. We will cut down on pollution and climate warming. Using renewable energy is not a dream for the future. It is happening right now right here today. 598 Appendix A General Science