Chapter 27 Section 1 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?

Chapter 27 Section 1 Disease Objectives Explain the 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 Causes of Disease Section 1 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 Pathways to Pathogens Air Contaminated Objects Section 1 Disease Pathways to Pathogens Air Contaminated Objects Person to Person Animals Food and Water

Putting Pathogens in Their Place Chapter 27 Section 1 Disease Putting Pathogens in Their Place Pasteurization The 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 Objectives Describe how your body keeps out pathogens. Section 2 Your Body’s Defenses Objectives Describe how your body keeps out pathogens. Explain how the immune system fights infections. Describe four challenges to the immune system.

Chapter 27 First Lines of Defense Section 2 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 Failure of First Lines Section 2 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.

Cells of the Immune System Chapter 27 Section 2 Your Body’s Defenses 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 Responding to a Virus Section 2 Your Body’s Defenses 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 Section 2 Your Body’s Defenses

Chapter 27 Section 2 Your Body’s Defenses

Chapter 27 Section 2 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 Section 2 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.

Challenges to the Immune System Chapter 27 Section 2 Your Body’s Defenses Challenges to the Immune System Allergies happen 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.

Challenges to the Immune System Chapter 27 Section 2 Your Body’s Defenses Challenges to the Immune System Cancer is a disease in which the cells begin dividing at an uncontrolled rate and become invasive. AIDS The 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.