The Immune System

What is the Immune System? What is a pathogen? Disease-causing organisms that can be present in air, water, food Pathogens are viruses, bacteria, fungi, protists, and parasites What is a disease? Any condition that prevents the body from working as it should What causes a disease? Pathogens, cancer, toxic substances, poor nutrition, organ malfunction, inherited disorders, or risky personal behavior What is an infection? Person has symptoms and medical signs of being infected by pathogen What is the Immune System? The body’s primary defense against disease-causing pathogens that enter body Immune system makes WHITE BLOOD CELLS and ANTIBODIES to destroy pathogens

Fighting Infectious Diseases: Nonspecific defenses: First line of Defense- Do not discriminate between one threat and another. Examples THE SKIN – the body’s most important line of defense Mucus, saliva, tears- contain enzymes to break down the cell walls of many bacteria Stomach acid – destroy pathogens that make it as far as your stomach

Specific Defenses Attack particular disease causing agents Kill foregin substances that enter body (shape-specific antibody production response) The reaction of the body to particular pathogens

Antibodies Proteins made by WBCs that recognize and bind to antigens. Carried through the bloodstream to attack the pathogen causing the infection. Antibodies attack invaders or mark them for destruction by other white blood cells- killer cells

Killer cells

Antigens Molecule found on the cell membrane of a pathogen or cancer cell Antigens cause immune system to react to presence of pathogens, toxins, cancer cells

What is passive immunity? Antibodies passed from mother to child through breast milk What is active immunity? Developed when exposed to antigen from fighting infection (example- chicken pox) or from antigen in vaccines (shots) White blood cells produced after exposure- (memory cells) What is a Toxin? Toxins are the poisonous wastes of certain pathogens like bacteria Toxins act as antigens

Active immunity

Disease can cause a Failure in Homeostasis What is Diabetes? Disease where your body is unable to produce insulin (hormone that lowers blood sugar) As a result, one is unable to control blood glucose levels What causes Diabetes? Type 1 Diabetes: birth defect- Missing gene Type 2 Diabetes: (Lifestyle) over-eating carbohydrates, poor diet and exercise Can Diabetes be cured? There is no known cure for diabetes Current research in gene therapy/splicing What is the treatment for Diabetes? Strict diet and glucose monitoring

What happens to a person with cancer? What is HIV? Human Immunodeficiency Virus destroys helper T cells ( type of white blood cell) What is AIDS? Acquired Immune Deficiency Syndrome occurs when immune system is weak an unable to fight off infections The majority of helper T-cells are destroyed What is cancer? Uncontrolled cell division and growth What happens to a person with cancer? The body might kill cancer cells if detected Life may be threatened if immune system can’t kill cancer cells Surgery, radiation, chemotherapy

What are White Blood Cells (Leucocytes)? Cells made by immune system to destroy pathogens, toxins, cancer cells Cells can tell difference between body cells and foreign invaders (pathogens) What are phagocytes? White blood cell that engulfs and digests pathogens

What are vaccines? What is a microbe? How do vaccines work? Consists of a weakened, killed or parts of a pathogen Injected into the body to stimulate immune system to produce antibodies that will kill microbes that enter body in future What is a microbe? Microscopic organism such as bacteria How do vaccines work? After entering body, antibodies are produced for that specific pathogen. After vaccination, immune system remembers pathogens by producing memory white blood cells that protect body for years. Memory white blood cells react quickly when invasion of same pathogen occurs.

What can damage the immune system? Immune system weakens with age Stress and fatigue Some viruses attack immune system and cause disease. What kinds of problems can occur with the immune system? Allergies, leukemia, AIDS What is an ALLERGY? A reaction to some substance (allergen) in environment that causes runny nose, sneezing, rash, or swelling What causes an allergic reaction? Allergens that are normally harmless What are some substances that can cause an allergic reaction? Certain foods, pollen, and chemicals from insect bites (bees/wasps) What is the response of the immune system in an allergic reaction? Immune system releases histamines that cause swelling, runny nose and rash

How can allergic reactions be treated? People can take antihistamines (drug) How does the immune system react to an organ transplant? What is tissue rejection? Immune system attacks transplant Transplant patient take drugs that suppress the immune system Tissue rejection is when transplanted organ is rejected in body White blood cells attack new organ What is antibiotic resistance? ANTIBIOTICS: drug that will kill pathogens like bacteria (not viruses) Pathogens are able to survive when exposed to antibiotics

What are infectious or communicative diseases? What is asthma? Disease where air passages narrow or thin This causes difficulty breathing Triggered by respiratory infections, exercise, stress, pollutants, mold, smoke, and pollen What is Leukemia? Cancer of the bone marrow or blood What are infectious or communicative diseases? Disease where pathogen can be spread through objects, sneezing, touching, food, water, insects and air

Examples of infectious disease: What are non infectious diseases? Bacteria, virus, protists What are non infectious diseases? Disease not caused by a pathogen Can not be passed to others (contagious) Examples of noninfectious diseases: Cancer, asthma, heart disease

Immune system Video KidsHealth.org http://kidshealth.org/kid/htbw/_bfs_ISmoviesource.html http://videos.howstuffworks.com/health/immune-system-videos.htm

Sample Regents Questions 1. Many bacteria that enter the circulatory system are engulfed and destroyed by  A.  phagocytic white blood cells B.  pinocytic red blood cells C.  plasma D.  platelets

2. Which molecule of the immune system attaches to bacteria, making them easier to eat by white blood cells? A. hemoglobin B. antibody C. antigen D. Pathogen

A. Enzymes B. Hormones C. Sugar D. Antibodies When a person is suffering from an infection, such as strep throat or chicken pox, his blood usually shows a significant increase in the number of A. Enzymes B. Hormones C. Sugar D. Antibodies

The Body is protected against harmful flu viruses by A. red blood cells and hormones B. white blood cells and antibodies C. white blood cells and enzymes D. red blood cells and antibodies

A vaccine can protect you against a disease because it A. destroys toxic substances from bacteria before they make you sick. B. stimulates your immune system against the pathogen. C. kills any pathogenic bacteria in your body D. changes pathogenic bacteria into harmless bacteria