Immune System and Disease Chapter 35

What are the basics? Homeostasis is the ability of an organism to maintain a stable internal environment. Diseases can disrupt this stability. Your immune system is the organ system that protects your body from disease. Your body has three different lines of defense against pathogens, or disease causing agents. To the Teacher: Take time to explain the importance of the circulatory system to the immune system. Ask students why they think the immune system could not function properly without the assistance of the circulatory system? If a pathogen does get into the body, the circulatory system helps fight the infection by transporting the immune system’s specialized cells to the source of infection

Infectious Diseases Occurs when pathogens cause a physiological changes that disrupt normal body functions Pathogens are disease-causing agents Infectious diseases can be caused by: Viruses (non-living) Bacteria Fungi Protists Parasites

How do diseases spread ? Coughing, Sneezing, Physical Contact Mostly infect the nose, throat and respiratory tract Exchange of body fluids Most sexually transmitted disease Contaminated water/food Affect the digestive tract Diarrhea is one common symptom Infected animals Mad cow disease, SARS, West Nile virus, bird flu, etc

What are the two types of immune defense? The immune system includes two general categories of defense mechanisms against infection. Nonspecific defenses guard against infections by keeping most things out of the body. Specific defenses track down harmful pathogens that have managed to break through the body’s nonspecific defenses. To the Teacher: Refer to essential question as students identify the differences between the two types of defense.

The Body’s Defense Systems Non-Specific Defense Specific Defense INNATE Immunity 1st and 2nd lines of defense 1st defense: Skin Saliva, mucus, tears 2nd defense: Inflammatory response ACQUIRED Immunity 3rd line of defense The body distinguishes between “self” and “foreigner” Respond to particular pathogens

Question Break: Why do you think the 1st and 2nd defense are called innate and the 3rd defense called acquired? HINT: Innate means “instinctual” or “born with” & acquired means to obtain

1st Line of Defense: Barriers to Infection To cause disease, a pathogen must invade the body. Your body has barriers to keep this pathogens out. Skin provides a protective barrier. Mucous membranes line up interior surfaces that come into contact with the environment. Pathogens that are swallowed are likely to be destroyed by your stomach acids. Sweat and tears contains salts, acids, and enzymes that help kill pathogens in your skin and eyes. To the Teacher: Ask students for the name of the structure in the pictures. Some students will recognize the Great Wall of China. Add a few factoids like it is over 1500 years old and it is the only man-made structure that can be seen from outer space. Ask students to explain why they think the Chinese built the wall? What organ in our body have a similar function?

2nd Line of Defense: Inflammatory Response The inflammatory response is the body’s response to tissue damage. As soon as pathogen enters your body, damaged tissue releases chemical signal (histamines). Blood vessels expand. What is a consequence of this? Plasma carries macrophages that engulf and destroy pathogens during phagocytosis If infection persists, body may increase temperature resulting in a fever. Why? To the Teacher: Using the information on this slide or the animation linked to the image (click on the far right side of image), have students make a graphic organizer in which they summarize the stages of the inflammatory response. You may ask students to include in their organizers the cause-and-effect relationships of the inflammatory response. A sample graphic organizer is shown below: Inflammatory response is triggered by damaged or infected cells consume invading pathogens which causes which release which attracts chemical alarm signals increased capillary permeability which cause white blood cells blood vessel dilation which which causes which causes suppresses bacterial growth which swelling temperature increases

3rd Line of Defense: Immune Response (Acquired immunity) The immune response attacks specific pathogens using specialized cells and proteins Leukocytes: white blood cells (2 types): T cells are white blood cells that attack and kill harmful bacteria. B cells are white blood cells that make antibodies. To the Teacher: Have students who have had chickenpox raise their hands. Have them keep their hands raised if they had it more than once. Ask them to explain why most, if not all, hands went down in response to the second question.

Signaling the problem An antigen is any foreign substance in the body and stimulates an immune response An antibody is a Y-shaped protein that attaches to a specific antigen, bind to the pathogen's membrane proteins Acts as a flag for destruction weaken the pathogen’s membrane Made by B-cells

Immune response has 2 styles of Action Humoral Response Signaling response Activates production of B-cells Cell-Mediated Response Destruction response Activates T-cell response

The Story of Your Body’s Soldiers An antigen of a pathogen attaches to an antibody of a B-cell Helper T-cells activate B cells to grow and divide rapidly into Plasma B-cells Memory B-cells (secondary response) Plasma B-cells release more antibodies that mark antigens for destruction

The Story of Your Body’s Soldiers Helper T-cells bind to antigen and are activated to go and activate: More helper T-cells- to activate B cells Cytotoxic T-cells Produce Memory T-cells (secondary Response) Bind to infected cells containing antigen destroy infected cell Puncture membrane Initiate apoptosis (cell suicide)

Secondary Response- Memory B and T cells The next time the same pathogen enters the body, the immune response is much faster at fighting it because of the memory B and T cells Memory B and T cells are already “trained” with the antibodies produced in the primary response Immunity: ability to resist disease Possible because of memory B and T cells

Homework Outline chapter 35.1

Immune System Day 2 Fighting Infectious Diseases

Bellringer- Review Specific Immune Response http://highered.mcgraw- hill.com/sites/0072507470/student_view0/chapter22/animati on__the_immune_response.html http://www.sciencelearn.org.nz/Contexts/Fighting- Infection/Sci-Media/Animations-and-Interactives/The- immune-system http://hippocampus.org/HippoCampus/Biology?loadLeftCla ss=CourseCombination&loadLeftId=9&loadTopicId=354

How do we fight infectious disease when our immune system isn’t strong enough on its own? CASE STUDY: Smallpox and Chicken Pox Smallpox was once found throughout the world. Caused illness and death wherever it occurred. Smallpox spreads easily from one person to another. People were once vaccinated against this disease.

Case Study: Small Pox The United States stopped giving the smallpox vaccine in 1972. In 1980, the World Health Organization (WHO) recommended that all countries stop vaccinating for smallpox. The vaccine is no longer given to the general public because the virus has been wiped out. Or has it?

The last naturally occurring case of smallpox was diagnosed on 26 October 1977. In ordinary type smallpox the bumps are filled with a thick, opaque fluid and often have a depression or dimple in the center.

Acquired Immunity More than 200 years ago, the English physician Edward Jenner wondered if it might be possible to produce immunity against smallpox. Jenner knew that people who had been affected by a mild disease called cowpox developed an immunity to smallpox.

Acquired Immunity Jenner took fluid from one of the sores of a cowpox patient and put the fluid into a small cut that he made on the arm of a young farm boy named Jamie Phillips. Two months later, he injected Jamie with fluid from a smallpox infection and … The rest is history. Breifly discuss medical ethics?

Active Immunity and Vaccination A Vaccination is the injection of a weakened or a similar but less dangerous form of a pathogen Stimulates immune system with an antigen Body produces memory B and T cells Quicken and Strengthen immune response This is an example of Active Immunity Natural exposure to antigen Deliberate exposure to antigen (Vaccine)

Vaccines Save Lives By Preventing Disease Vaccine’s prevent the infection of a pathogen There are vaccines for more than 20 serious human diseases Not every disease has a vaccine that we have discovered

Passive Immunity Diseases can be prevented also by injecting antibodies produced by other animals or individuals This gives an individual temporary immunity Immune system eventually destroys foreign antibody Can also occur Naturally (through mother’s breast milk or placental transfusion) Deliberately (injection)

Both can occur naturally or deliberately See the Difference? Active Immunity Inject a pathogen Long-term immunity Strengthens immune system Passive Immunity Inject antibodies Short-term immunity Temporarily defeats pathogen Both can occur naturally or deliberately

Antibiotics Antibiotics drugs are those that can kill bacteria without harming the host Ex: Penicillium They have NO effect on viruses Why? (hint- break down the word) There are, however, antiviral drugs that can slow down viral activity Viruses are very difficult to get rid of Some never are able to leave your body

New and Re-emerging Diseases Why are infectious diseases changing? New Diseases coming from ongoing merging of human and animal habitats Misuse of medications Evolving resistance to drugs http://wps.prenhall.com/esm_freeman_biosci_1/0,6452,499512-,00.html

Immune System Day 3 Immune System Disorders

Misguided Immune Response Sometimes an strong immune response to a harmless antigen will produce Allergies Asthma Autoimmune diseases Harmless particles: pollen, dust mites, mold, pet dander, their own cells

Allergies Allergens: antigens that cause allergies When an allergen enters the body, the inflammatory response is triggered Mast cells release histamines Symptoms: rashes, sneezing, watery eyes, runny nose Antihistamines are drugs that relieve allergy symptoms

Asthma Allergic reaction in the respiratory system Triggered by: Air passages narrow Causing short breath, wheezing, coughing Triggered by: Genetic predisposition Environmental factors Respiratory infections Exercise Emotional distress Cold/dry air Smoke, dust, pet dander, etc

Autoimmune diseases Sometimes diseases occur where the immune system fails to properly recognize “self” Attacks the own body’s cells or compounds Thinks they are pathogens Examples: Type I diabetes Rheumatoid Arthritis Lupus Some treatments can alleviate symptoms and some suppress the immune response Sadly, there are no cures

HIV/AIDS- Human Immunodeficiency HIV- Human Immunodeficiency Virus The CAUSE of AIDS Known as a retrovirus Attacks the Helper T-Cells Becomes difficult for the immune response to defend against diseases and pathogens AIDS- Acquired Immunodeficiency Syndrome When the amount of T-cells in the body is reduced to less than 1/6 normal count

HIV and AIDS attacks the immune system HIV/AIDS is not actually the killer itself directly The disease debilitates the immune system The immune system can no longer efficiently respond to pathogens it normally fights off Causes opportunistic diseases- diseases that attack a person with a weakened immune system

Spread and Prevention Only transmitted through contact with Infected blood Semen Vaginal Secretions Breast milk 4 main ways it spreads: Sexual intercourse Shared needles Blood contact Mother-to-child (during pregnancy, birth, breast-feeding

Spread and Prevention No-risk behavior includes Sexual abstinence Intravenous drug-use abstinence Many people do not know they have HIV/AIDS because they have not progressed far enough in the disease This is why it is so important to KNOW a potential sexual partner EVERYONE being tested is essential to stop the spread

There is NO cure. Currently there s no cure for aids Only drugs that can help survive for some years VERY expensive DEADLY misconception Just because there are treatments, some people now believe AIDS is not serious DEAD WRONG http://www.whitehouse.gov/admi nistration/eop/onap/nhas