The Immune System
Disease: any change, other than an injury, that disrupts homeostasis. Pathogen: disease-causing agent such as bacteria, virus, etc. Infectious disease- caused by pathogen Germ theory of disease: Infectious disease caused by pathogen
Virus: Tiny Particles that invade and replicate within living cells. Mechanism: viruses attach to the surface of the cell insert their genetic material in the form of RNA or DNA into the host cell Replicate within the host cell Take over the functions of the host cell
Viruses and Bacteria
VIRUSES Examples: HIV, Avian Flu, the Flu, Colds, Herpes, HPV, Chicken Pox, Small Pox, Measles, Mumps, West Nile, Malaria, Rabies, Hantavirus
BACTERIA Single celled Prokaryotes. Most are harmless but some cause serious disease. Two Mechanisms: 1. Break down the tissues of the infected organism for food 2. Release toxins that harm the body
BACTERIA Examples: Streptococcus, diphtheria, botulism, anthrax, gonorrhea, syphilis, Chlamydia
Pathogens and Disease stop Section 40-1 Pathogen Types Disease Agent That Causes Disease Method of Transmission Viruses Bacteria Protists Worms Fungi Common cold Influenza Chickenpox Measles Tuberculosis Meningitis Cholera Tetanus African sleeping sickness Malaria Amoebic dysentery Schistosomiasis Beef tapeworm Athlete s foot Ringworm Rhinovirus Two types (A, B), plus subtypes Varicella Paramyxovirus Mycobacterium tuberculosis Neisseria meningitidis Vibrio cholerae Clostridium tetani Trypanosoma Plasmodium Entamoeba histolytica Schistosoma Taenia saginata Imperfect fungi Imperfect fungi Airborne; direct contact with infected person Airborne; droplet infection; direct contact with infected person Airborne; direct contact with infected person Droplets in air; direct contact with secretions of infected person Droplets in air; contaminated milk and dairy products Direct contact with a carrier Contaminated drinking water Contaminated wound; usually puncture wound Spread by tsetse fly Spread by Anopheles mosquitoes Contaminated drinking water Freshwater streams and rice paddies Contaminated meat Contact with infected person Exchange of hats, combs, or athletic head gear with infected person
Antibiotics Kill bacteria without harming host cells. Do not work against viruses! (colds, flu)
How are Diseases spread? 1. Sexual contact Indirect Sneezing, coughing
2. Contaminated food, water Food poisoning Bacteria in uncooked or partially cooked food 3. Infected animals Malaria, Lyme disease, West Nile virus
What is the immune system? Specialized cells white blood cells Separate circulatory system lymphatic system Designed to protect against disease
What makes a good system for fighting invaders?
Characteristics of immune system Specific Specific defense activated by antigen Antigen: anything that causes an immune response- bee sting, pollen, bacteria
Versatile Produces many different lymphocytes Each has different antigen receptors
Memory Ready to fight same invader if it strikes again Chickenpox only once Vaccines prepare system for potential Measles, mumps, tetnus
Tolerant Does not destroy own cells
A.Non-Specific Defenses Will fight anything
1. First line of defense Skin Dead skin cells provide barrier
Secretions Mucous Saliva Tears Sweat contain enzymes to break down bacteria cell walls Wash away pathogens
Cilia In nose and throat Keep pathogens from getting into lungs
Stomach acid Low ph destroys many pathogens.
2. Second line of defense
Section 40-2 Ouch! Skin Wound Phagocytes move into the area and engulf the bacteria and cell debris Bacteria enter the wound Capillary
Inflammatory response Reaction to injury, infection Redness, swelling, heat Phagocytosis white blood cells eat invading agent Destroys toxic agents
Bacteria
Fever Kills some pathogens Increases metabolic rate Produce more white blood cells
Increased heart rate Pumps white cells to infection site faster
Interferons Proteins that destroy viruses
B. Specific Defense
T- cells and B-cells White blood cells (lymphocytes) T cells and B cells Work together to fight foreign agent Antigen: Substance on surface of pathogen that triggers an immune response
1. Humoral Immunity- B cells In blood stream and lymphatic system (body fluids) B cells grow, divide rapidly Produce: Plasma cells Memory cells
Plasma cells Make and release antibodies Recognize and bind to antigen (pathogen) Tag them for destruction by T cells.
Antibodies Proteins Y-shaped Binding sites for antigens Match shape of antigen- specific 100 million different types of antibodies in healthy adult
Structure of an Antibody Section 40-2 Antigenbinding sites Antigen Antibody
(macrophages)
Memory B cells Remember antigen Can produces more antibodies quickly if exposed again Plasma B cells make more antibodies quickly.
Vaccines Weakened, dead, or fragment of pathogen Causes immune response Body is ready to fight if exposed to agent
Antibody Concentration Primary and Secondary Immune Section 40-2 Responses Interval between exposures First exposure Second exposure Time
Humoral Immunity Section 40-2
2. Cell-mediated immunity Works inside cell if pathogen gets in Viruses small enough to enter cell Invader eaten by T-cell
Many types of T- Cells Invader? After macrophage has eaten virus or bacteria, it puts parts of it on the outside of itself. T Cells recognize this as foreign and go into action!
Helper T-cell Help B-cells make antibodies by passing along information about pathogen Divides to become other types of T-Cells
Killer T-cell stored in tonsils, lymph nodes travel to infected site kill cells that have been infected by pathogen
Memory T-Cells Suppressor T-Cells When invader is totally destroyed, suppresses further immune activity
Section 40-2 Macrophage T cell binds to activated macrophage Helper T Cell Helper T cell activates killer T cells and B cells Killer T Cell Antigens are displayed on surface of macrophage T Cell T cell, activated by macrophage, becomes a helper T cell Infected Cell Killer T cells bind to infected cells, disrupting their cell membranes and destroying them
Disorders of Immune System
Allergies Immune system over-reacts to antigen Inflammatory response Asthma Runny nose, etc. Bronchial tubes constrict (get smaller)
Auto-immune diseases Multiple Sclerosis Antibodies attack nerve cells Rheumatoid Arthritis Antibodies attack connective tissue around joints. Diabetes Antibodies attack pancreatic cells.
Healthy Living Healthy Diet Few saturated fats MANY fruits and vegetables Exercise Increases metabolism Rest 8-9 hours/night recommended for teens! Don t engage in risky behaviors AIDS is fully preventable. Tobacco-related cancers, disease fully preventable.