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Transcript
The Immune System “Bad boys, bad boys, whatcha gonna do when they come for you?” Pathogens Vs. White Blood Cells Terms to Know • • • • • • • • • • Pathogen Communicable disease Non communicable disease Immune system Bacteria viruses Leukocytes Phagocytosis T lymphocytes B lymphocytes • • • • • • • • Immunity Spleen Thymus gland Bone marrow Allergic response Antigen Antibody Innate and passive immunity • Interferon • inflammation Communicable Diseases • These are diseases that are contagious • They are caused by a pathogen, a disease causing organism, or chemical. • Examples of communicable diseases: pneumonia, common cold, tuberculosis, chicken pox, HIV, and more • Samantha goes to the bathroom in a public restroom where several people infected with the flu just used the same bathroom. What tips can you give Samantha to help prevent her from contracting the flu virus germs? • Use a paper towel to flush toilet and open the door of the bathroom stall door • Use a paper towel to turn off the faucet after you wash your hands to avoid recontamination • Scrub your hands with soap for at least 15 seconds • Open the door with a paper towel to exit the restroom Non-Communicable Diseases • Diseases that are not contagious • Examples: cancer, genetic diseases, diabetes, cirrhosis, emphysema, etc Types of Pathogens Bacteria Fungi Viruses This is a picture of a bacterium, a prokaryote cell Notice, it does not contain a nucleus DNA is coiled up in the center BACTERIA • These are a large group of unicellular organisms • They come in three shapes: sphere, rod, and spiral shaped • They can be found everywhere on Earth- in soil, acidic hot springs, water, and deep in the earth’s crust • There are large number of bacterial cells in the human digestive tract and skin • Most bacteria are not harmful, and some are beneficial- antibiotics are used to destroy bacteria Viruses Viruses are infectious agents that are not able to grow outside a host’s cellthey take over the host’s DNA to make more copies of their cells Viruses are 100 times smaller than bacteria Contain-DNA and RNA, protein coat, and a tail. Some have an envelope of fat to protect them when outside a host HIV-Human Immunodeficiency Virus- the virus responsible for causing AIDS Functions • The immune system is the body’s defense against infectious organisms and other invaders • Through a series of steps called the immune response, the immune system attacks organisms and substances that invade our system and cause disease The Body’s First Line of Defense • Billions of bacteria are floating around every second of your life, most of them harmless to you • Openings through which bacteria enter the body are the mouth, ears, nose, eye, or cut in skin • Your skin is your first line of defense against them. It does its best to keep out bacteria and other pathogens The Second Line of Defense • Mucus/cilia-mucus in the nasal passageway and upper respiratory tract help trap pathogens, while cilia sweep them away • Earwax-helps trap in foreign material • Tears and sweat- have anti-microbial agents called lysozyme • Saliva- destroys harmful organisms in the mouth because it also has lysozymes • Stomach acid- kills some pathogen that enter with food White Blood Cells-The Body’s Third Line of Defense (the “cops”) • The cells that are part of the immune system are the white blood cells, also called leukocytes • They are produced or stored in may places in the body including the thymus gland, spleen, and bone marrow • There are also clumps of lymphoid tissue, primarily lymph nodes, that house leukocytes • When pathogens have slipped passed the first and second line of defenses- your WBC’s step in to help Some leukocytes are produced in the thymus and in the spleen Spleen • A small organ located just under the left diaphragm • It creates lymphocytes for the destruction and recycling of old red blood cells • It is also a blood reservoir, supplying the body blood in the case of an emergency, such as a bad cut • It is also the location where white blood cells trap microorganisms The Inflammatory Response When you have a cut, bee sting, or splinter in your finger- here is what happens: 1. Blood supply to the area increases and circulation in that area decreases. 2. Blood pressure in the area increases causing blood to leak from the blood vessel. 3. As a result, swelling, pain, heat, and redness happens- this is called inflammation The Inflammatory Response Two Types of Leukocytes (white blood cells) • PhagocytesThese are the white blood cells that chew up, or eat invading organisms • LymphocytesThese are the white blood cells that allow the body to remember and recognize previous invaders Phagocytosis • Neutrophils and other phagocytes engulf their bacteria, or other invader, through a process called phagocytosis • Any molecule that binds to a microorganism and speeds phagocytosis is called an opsonin (antibodies are an example) A white blood cell “engulfing” bacteria Neutrophil • This is the most common type of phagocyte in the immune system, makes up about 65% of WBC’s • They primarily fight bacteria When doctors are worried about a bacterial infection, sometimes they order a blood test to see if a patient has an increased number of neutrophils, triggered by the infection Heat as a Way to Kill Germs • Some phagocytes release chemicals that cause a fever. The high temperature doesn’t make you feel so good, but it does help to kill of some of the disease causing germs. Germs prefer a temperature of 98.6degrees Other phagocytes • • • • Basophils Neutrophils Monocytes eusonophils All lymphocytes start off in the bone marrow. There are two types: • B lymphocytes- these are the lymphocytes that stay in the bone marrow and mature into B cells • B cells produce antibodies • T lymphocytes- these are the lymphocytes that leave the bone marrow to go to the thymus gland and mature into T cells Antibodies and Antigens • Each germ has proteins called antigens on their surface • An antigen is a molecule, usually a protein, that acts as a marker for cells, as well as bacteria, viruses, or any other foreign substance that enters the body • Antibodies are proteins that attach to the germ’s antigens preventing the germ from infecting cells • Antibodies are made by the B cells Antibodies and Antigens Fit Together Like a Lock and Key How it Works • A foreign substance, an antigen, enters the body • When it is detected, several types of cells work together to recognize and respond to it • These cells trigger B lymphocytes to produce antibodies • The antibodies lock onto specific antigens, so that they can no longer infect other cells • Once the B cells have produced antibodies, these antibodies continue to persist in a person’s body • That means if the same antigen is presented to the immune system again, the antibodies are ready to do their job • That is why if someone already got sick from the chicken pox, the person is not likely to get sick from it again • This is also why we use immunization to prevent getting certain diseases • Although antibodies can recognize an antigen and lock on to it, they are not capable of destroying it without help • The T cells are the part of the system that destroys the antigens tagged by the antibodies, or cells that have been infected or somehow changed • T cells also signal other cells, like phagocytes, to do their jobs Helper T cells • Helper T cells are in command • They control the entire system and give orders about how to destroy the germs • Basically, they signal B cells and killer T cells to come to the rescue at an infection site B cells • B cells leave the bone marrow to fight germs with their antibodies • They mark germs with antibodies Killer T cells • These cells bump into infected cells, poke holes into them and destroy Suppressor T cells • Suppressor T-cells get there when the battle is over and it looks safe • They tell the killer Tcells to stop fighting Memory T cells • Memory T- cells are sent after the suppressor T- cells • They patrol the area and watch for a germ’s return • If the germ returns, they alert the system which already has a strategy for fighting this germ Allergies • Sometimes immune cells have poor recognition capabilities and mistake a harmless allergen for a dangerous pathogen • This results in an inappropriate allergic response Immunity • All of these specialized cells and parts of the immune system offer the body protection against disease • This protection is called immunity • Humans have three types of immunity- innate, active, and passive Innate Immunity • Everyone is born with innate (or natural/born with it) immunity, a type of general protection everyone has • Many of the germs that affect other species, don’t harm us • For example, viruses that cause leukemia in cats or stemper in dogs, don’t harm humans • Vice versa, some viruses, such as HIV, make humans ill, but not cats or dogs Active Immunity • We also have a second kind of protection called active immunity where immunity develops throughout our lives • Active immunity involves lymphocytes and • It develops as children and adults are exposed to diseases or immunized against diseases through vaccination Passive Immunity • Passive immunity is “borrowed” from another source and it lasts for a short time • For example, antibodies in a mother’s breast milk provide an infant with temporary immunity to diseases that the mother has been exposed to • This can help protect the infant against infection during the early years of childhood We Are All Different • Everyone’s immune system is different • Some people never seem to get sick whereas others seem to be sick all the time • As a person gets older, he or she usually becomes immune to more germs as the immune system comes in contact with more and more of them • That is why adults and teens tend to get fewer colds than children- their bodies have learned to recognize and immediately attack many of the viruses that cause colds One Last Note • The thymus gland begins to shrink after the age of sixty or so, due to a drop in the production of the HGH (human growth hormone). • This results in the production of less T cells, this is one reason elderly people have a harder time fighting off an infection than young people do Ways To Care For Your Immune System #1 Avoid The Use of Drugs- Drugs and Drinking Too Much Alcohol Can weaken the Immune System #2 Eat Healthy Foods Fruits Vegetables Whole Grains Lean Meats And occasionally treat yourself to a bite of chocolate or a cup of low fat ice cream (or Pinkberry’s) #3 Reduce the Amount of Stress in Your Life Don’t wait until the last minute to study for a test or work on a project, this can cause stress- plan ahead Take a little time each night to do some school work See your teachers, counselors, or parents if you need help with school work or anything else that is on your mind Because Stress Can Weaken the Immune System, making it easier to get sick So, #4 is Find Time to Relax Just Relax a Bit And Tell Your Parents to Take You to The Beach this weekend- tell them it will help you relax and strengthen your immune system And maybe end the day with an ice cream cone