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Resources Bellringers Chapter Presentation Transparencies Standardized Test Prep Image and Math Focus Bank CNN Videos Visual Concepts

Body Defenses and Disease Chapter 27 Table of Contents Section 1 Disease Section 2 Your Body’s Defenses

Chapter 27 Section1 Disease Bellringer • Brainstorm as many different names of diseases as you can. Don’t forget to list both physical illnesses and mental illnesses. How do you think people get these diseases? • Record your answers in your science journal.

Chapter 27 Section1 Disease Objectives • Explainthe difference between infectious diseases and noninfectious disease. • Identify five ways that you might come into contact with a pathogen. • Discuss four methods that have helped reduce the spread of disease.

Chapter 27 Section1 Disease Causes of Disease • Some diseases, such as most cancers and heart disease, are not spread from one person to another. They are called noninfectious diseases. • A disease that can be passed from one living thing to another is an infectious disease. Infectious diseases are caused by agents called pathogens.

Chapter 27 Section1 Disease Pathways to Pathogens • Air Some pathogens travel through the air, such as when someone sneezes. • Contaminated Objects Drinking glasses, doorknobs, keyboards, combs, and towels that have been used by an infected person can all pass pathogens.

Chapter 27 Section1 Disease Pathways to Pathogens, continued • Person to PersonYou can become infected with some illnesses by kissing, shaking hands, or touching the sores of an infected person. • Animals Some pathogens are carried by animals. • Food and Water Bacteria growing in foods and beverages can cause illness.

Chapter 27 Section1 Disease Putting Pathogens in Their Place • PasteurizationThe method of using heat to kill bacteria is called pasteurization. • Vaccines and Immunity The ability to resist or recover from an infectious disease is called immunity. A vaccine is a substance that helps your body develop immunity to a disease. • Antibiotics An antibiotic is a substance that can kill bacteria or slow the growth of bacteria.

Chapter 27 Section2 Your Body’s Defenses Bellringer • Make a list in your science journalof all the different ways pathogens might enter the body. Is there anything that you do to avoid getting sick? Do you know of anything that your body automatically does to get rid of pathogens?

Chapter 27 Section2 Your Body’s Defenses Objectives • Describehow your body keeps out pathogens. • Explain how the immune system fights infections. • Describe four challenges to the immune system.

Chapter 27 Section2 Your Body’s Defenses First Lines of Defense • Your skin is made of many layers of flat cells. The outermost layers are dead. As a result, many pathogens that land on your skin have difficulty finding a live cell to infect.

Chapter 27 Section2 Your Body’s Defenses Failure of First Lines • Sometimes, skin is cut or punctured and pathogens can enter the body. Cell parts in the blood called platelets help seal the open wound so that no more pathogens can enter. • The cells and tissues that recognize and attack foreign substances in the body belong to the immune system.

Section2 Your Body’s Defenses Chapter 27 Cells of the Immune System • Macrophages engulf and digest many microorganisms or viruses that enter your body. • T cells coordinate the immune system and attack many infected cells. • B cells are immune-system cells that make antibodies. Antibodies are proteins that attach to specific antigens.

Chapter 27 Section2 Your Body’s Defenses

Section2 Your Body’s Defenses Chapter 27 Responding to a Virus • If virus particles enter your body, some of the particles may pass into body cells and begin to replicate. • Other virus particles will be engulfed and broken up by macrophages. This is just the beginning of the immune response.

Chapter 27 Section2 Your Body’s Defenses

Chapter 27 Section2 Your Body’s Defenses Fevers • A moderate fever of one or two degrees actually helps you get well faster because it slows the growth of some pathogens. • A fever also helps B cells and T cells multiply faster.

Chapter 27 Section2 Your Body’s Defenses Memory Cells • Memory B cells are cells in your immune system that “remember” how to make an antibody for a particular pathogen. • If the pathogen shows up again, the memory B cells produce B cells that make enough antibodies in just 3 or 4 days to protect you.

Section2 Your Body’s Defenses Chapter 27 Primary and Secondary Immune Response Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Section2 Your Body’s Defenses Chapter 27 Challenges to the Immune System • Allergieshappen when the immune system overreacts to antigens that are not dangerous to the body. • Autoimmune Disease is a disease in which the immune system attacks the body’s own cells. In an autoimmune disease, immune-system cells mistake body cells for pathogens.

Section2 Your Body’s Defenses Chapter 27 Challenges to the Immune System, continued • Canceris a disease in which the cells begin dividing at an uncontrolled rate and become invasive. • AIDSThe human immunodeficiency virus (HIV) causes acquired immune deficiency syndrome (AIDS). HIV infects the immune system itself, using helper T cells as factories to produce more viruses.

Chapter 27 Body Defenses and Disease Concept Map Use the terms below to complete the concept map on the next slide.

Chapter 27 Concept Map

End of Chapter 27 Show

Chapter 27 Body Defenses and Disease CNN Videos • Scientists in Action: In Search of Nature’s Cures • Science, Technology, and Society: Computer Healing

Standardized Test Preparation Chapter 27 Reading Read each of the passages. Then, answer the questions that follow each passage.

Standardized Test Preparation Chapter 27 Passage 1Bacteria are becoming resistant to many human-made antibiotics, which means that the drugs no longer affect the bacteria. Scientists now face the challenge of developing new antibiotics that can overcome the resistant strains of bacteria. Antibiotics from animals are different from some human-made antibiotics. Continued on the next slide

Standardized Test Preparation Chapter 27 Passage 1, continuedThese antibiotics bore holes through the membranes that surround bacterial cells, causing the cells to disintegrate and die. Bacterial membranes don’t mutate often, so they are less likely to become resistant to the animal antibiotics.

Standardized Test Preparation Chapter 27 1. In this passage, what does mutate mean? A to change B to grow C to form D to degrade

Standardized Test Preparation Chapter 27 2. Based on the passage, which of the following statements is a fact? F Bacterial membranes are on the inside of the bacterial cell. G Bacterial membranes are on the outside of the bacterial cell. H All strains of bacteria mutate. I Bacterial membranes never change.

Standardized Test Preparation Chapter 27 3.Based on the passage, which of the following sentences is false? A Antibiotics from animals are different from human-made antibiotics. B Antibiotics from animals bore holes in bacterial membranes. C Bacterial membranes don’t change very often. D Bacteria rarely develop resistance to human-made antibiotics.

Standardized Test Preparation Chapter 27 Passage 2Drinking water in the United States is generally safe, but water lines can break, or treatment plants can become flooded, allowing microorganisms to enter the public water supply. Bacteria growing in foods and beverages can cause illness, too. Continued on the next slide

Standardized Test Preparation Chapter 27 Passage 2, continuedRefrigerating foods can slow the growth of many of these pathogens, but meat, fish, and eggs that are not cooked enough can still contain dangerous bacteria or parasites. Leaving food out at room temperature can give bacteria such as salmonella time to grow and produce toxins in the food. For these reasons, it is important to wash all used cooking tools.

Standardized Test Preparation Chapter 27 1.Which of the following statements can you infer from this passage? A Treatment plants help keep drinking water safe. B Treatment plants never become flooded. C Eliminating treatment plants would help keep water safe. D New treatment plants are better than old ones.

Standardized Test Preparation Chapter 27 2. Which of the following statements can you infer from the passage? F Bacteria that live in food produce more toxins than molds produce. G Cooking food thoroughly kills bacteria living in the food. H Some bacteria are helpful to humans. I Illnesses caused by bacteria living in food are seldom serious.

Standardized Test Preparation Chapter 27 3. According to this passage, what do pathogens cause? A disease B flooding C water-line breaks D water supplies

Standardized Test Preparation Chapter 27 Interpreting Graphics The graph below shows the reported number of people living with HIV/AIDS. Use the graph to answer the questions that follow.

Standardized Test Preparation Chapter 27 1. When did the number of people living with HIV/AIDS reach 5 million? A 1985 B 1986 C 1987 D 1988

Standardized Test Preparation Chapter 27 2. When did the number of people living with HIV/AIDS reach 30 million? F 1996 G 1997 H 1998 I 1999

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