Bones and Muscles Review and Reinforce Organ Systems and Homeostasis Understanding Main Ideas The illustration below shows the units of organization in a reptile. The units are numbered 1 4. Label the numbered units of organization in the spaces provided. 4 3 2 2 1 1 Bones and Muscles 1. 2. 3. 4. Building Vocabulary Fill in the blank to complete each statement. 5. is the body s tendency to keep an internal balance. 6. tissue makes up organs that are able to contract, or shorten. tissue makes up the organs that send messages to control the body. 7. The inside of the digestive system is lined with tissue. 8. The kidney is a(n). The excretory system is a(n). 9. The major organs of the excretory system are the. 10. tissue provides support for your body and connects all its parts. 11. Disease-causing bacteria or viruses are known as. 17
Bones and Muscles Enrich Organ and Tissue Transplants When a doctor performs a transplant operation, he or she replaces a diseased or damaged organ or tissue. Sometimes a tissue is moved from one place to another on the same person. This procedure is called an autograft. (Automeans self, and -graft means transplant. ) A burn victim may have an autograft in which a section of his or her healthy skin is transplanted to cover the burn. Sometimes a person receives an organ or tissue from another person. This is called an allograft. (Allo- means different. ) An example of an allograft is the transplantation of a kidney from the body of one person into that of another person. One problem with allografts is rejection. Rejection occurs when the patient s body recognizes the transplanted organ or tissues as foreign, similar to the way in which a mother cat recognizes a kitten from another litter as not belonging to her. Rejection is a serious problem because the body begins to attack the transplanted organ or tissue. One way of preventing rejection is by giving the patient certain drugs. Transplants are performed to save a patient s life or to correct a serious medical condition. For example, a person with severe liver disease might cornea lung blood liver bone small intestine cartilage tendon need a new liver in order to survive. Transplanting a part of the eye called the cornea can help some blind people to see. The illustration shows some of the many organs and tissues that doctors can transplant. middle ear heart pancreas kidney skin veins Answer the following questions on a separate sheet of paper. 1. Autografts are never rejected. Why do you think this is true? 2. Why do you think doctors try to use autografts rather than allografts on burn patients? 3. A patient s body is less likely to reject an allograft if it comes from a close relative. Why do you think this is true? 4. Do you think doctors would have more difficulty transplanting an organ system than transplanting an organ? Think of an example to explain your answer. 18
Bones and Muscles Review and Reinforce The Skeletal System Understanding Main Ideas Answer the following questions on a separate sheet of paper. 1. Name the five functions of the skeleton. 2. What lifestyle choices help keep bones healthy and strong? 3. What do movable joints enable the body to do? What are the four types of movable joints? Label the numbered parts of the femur below in the spaces provided. 4. 5. 6. 5. 7. 7. 6. 4. Building Vocabulary Fill in the blank to complete each statement. 8. A place in the body where two bones come together is a(n). 9. is a condition in which the body s bones become weak and break easily. 10. A(n) is one of the 26 small bones that make up your backbone. 11. The tip of your nose is able to move from side to side because it is made up of a connective tissue that is more flexible than bone. This type of tissue is called. 12. A(n) is the strong connective tissue that holds the bones together in a movable joint. 20
Bones and Muscles Enrich A Pain in the Back Many animals support their backs by walking on four legs. However, humans evolved to walk upright on only two legs. Two legs provide much less support and balance for the backbone. Some scientists think that this is one reason why humans are likely to suffer from back pain. As a matter of fact, back pain is second only to headache as the most frequent cause of pain in humans. Back pain can be caused by such things as incorrect posture when sitting or standing, lifting heavy objects incorrectly, sleeping on a mattress that does not provide enough support for the neck and back, or being overweight. Also, working on a computer that is not correctly positioned can be responsible for back pain. Even stress can cause a painful back. The figures below illustrate the correct way to sit while working at a computer and to lift heavy objects. Sitting at a Computer Don t slouch. Sit with your lower back against the back of the chair. The keyboard should be directly in front of you. The screen should be centered in front of you and the top of the screen should be at eye level. Bones and Muscles Lifting Heavy Objects First, make sure you can lift the object without straining. Then lift by bending at your knees, not at your back. Keep the object as close to your body as possible. Don t twist your body. It is better to push a heavy object than to pull it. Answer the following questions on a separate sheet of paper. 1. Why do you think the computer keyboard and screen should be centered directly in front of the person seated at a computer? 2. You are helping your next-door neighbor move some boxes of books from your house to his. How should you move the boxes to avoid injuring your back? 3. What type of shoes do you think would be likely to cause back pain? Why? 4. A friend tells you she has a pain in her lower back. What are some backcare tips you could give her? 21
Bones and Muscles Review and Reinforce The Muscular System Understanding Main Ideas Complete the table below to describe the characteristics of each type of muscle. Write yes or no next to each number. Muscle Types Voluntary Involuntary Reacts quickly Tires quickly Skeletal 1. 2. 3. 4. Bones and Muscles Smooth 5. 6. 7. 8. Cardiac 9. 10. 11. 12. Answer the following questions in the spaces provided. 13.Why do skeletal muscles have to work in pairs? 14.How can you help prevent muscle injuries? Building Vocabulary Answer the following questions with a short statement. 15.What types of actions are controlled by smooth muscles? What type of muscle is smooth muscle? 16.What types of actions are controlled by skeletal muscles? What type of muscle is skeletal muscle? 17.How is cardiac muscle similar to both smooth muscle and skeletal muscle? 23
Bones and Muscles Enrich Pumping Iron You know that exercise builds muscles, but how? When you exercise properly, you make individual muscle cells grow wider by stimulating protein synthesis. This causes the muscle to become thicker. Muscles increase in strength as they become thicker. Any exercise that makes a muscle try to move an immovable object or to lift a heavy one can work toward increasing that muscle s strength. You can increase the difficulty of the exercise by adding additional weight. The figure below demonstrates a biceps curl, a common strength-training exercise used to build arm muscles. The arrows show the direction of movement, and the circles represent a weight. Biceps contracted Movement of weight Triceps relaxed Answer the following questions in the spaces provided. 1. How does exercise build muscles? 2. How can you increase the amount of exercise your arm muscles can do in the exercise pictured above? 3. How does the exercise shown above demonstrate that skeletal muscles must work in pairs? 4. Can you think of any exercises that would build the biceps and triceps without the use of hand weights? 24
Bones and Muscles Review and Reinforce Machines and the Body Understanding Main Ideas Answer the following questions in the spaces provided. 1. How are force and work related? 2. How does a lever make work easier? 3. How do the three classes of levers work? 4. Explain the most common machine in the human body. Building Vocabulary Match each term with its definition by writing the letter of the correct definition on the line beside the term in the left column. 5. effort force 6. machine 7. effort arm 8. mechanical advantage 9. fulcrum 10. resistance force 11. resistance arm 12. work 13. effort distance 14. resistance distance 15. lever 16. force a. exerting a force on an object that causes it to move in the same direction as the force b. the disatance a lever pushes up on an object c. the distance you push down on a lever d. a rigid rod that is free to rotate around a fixed point e. the force a lever exerts on an object f. a push or pull on an object g. the force you exert on a lever h. the distance from the fulcrum to the resistance force i. the number of times a lever increases a force j. the fixed pivot point in a lever k. the distance from the fulcrum to the effort force l. a device that makes work eaiser 26
Bones and Muscles Enrich An Ancient Machine Ancient societies did not have machines that ran on electric current, coal, or gasoline. For this reason, ancient engineers needed to use the energy generated from human and animal muscles as efficiently as possible. One example of an ancient machine is the treadmill. This was a hollow wheel, large enough for someone to stand inside. In the example below, a treadmill is used to lift water from a well. As the man tries to walk up the curved inner surface of the wheel, the force of gravity pulls his body back to the bottom and turns the wheel. The work performed by the man in the wheel turns an axle that drives a belt to move buckets down into a well, where they fill with water, and then come back up. The man turning the wheel supplies the input force, and water is pulled up from the well by the output force. In this example, the man has a mass of 75 kg. With each step, he raises his body 0.5 m, and is pulled back down by the force of gravity. Each step that he takes causes the conveyor to lift 750 kg of water a distance of 0.05 m. Bones and Muscles Answer the questions below on a separate sheet. Show your calculations. 1. When the man inside the treadmill steps up, what force pulls him back? In what direction does this force move him? 2. Gravity accelerates objects downward at 9.8 m/s 2. How much downward force does the man generate with each step he takes? How much work is performed when gravity pulls him down 0.5 m after each step? 3. How much force is exerted to lift 750 kg of water in the well against the force of gravity? How much work is done to lift this water 0.05 m? How does this compare to the work done by the man in the treadmill? 4. Remember, the treadmill is a machine. What is the input force exerted by the man inside the wheel? What is the output force exerted upon the water rising from the well? What is the mechanical advantage of this machine? 5. Calculate the efficiency of this treadmill. Is this likely? What factor might cause a real treadmill to be less efficient? 27