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Biology 30SThe Immune System6711951143000ObjectivesBy the end of this unit students will be able to:Describe the body’s defense mechanisms for protection from foreign agents. Compare and contrast non-specific verses specific defenses.Describe the body’s response to allergens, vaccines, and viruses/bacteria. Outline the immune responseInvestigate and describe conditions/disorders that affect protection and/or control in the human body.The IMMUNE SYSTEMWhat is the immune system?The immune system is the body’s defense against disease causing organisms, malfunctioning cells, and foreign particles. To have immunity means that your body is able to fight off disease and develop resistance to them. These infectious/contagious/communicable diseases are ones that spread from one infected organism to another organism. Diseases can be caused by inorganic toxins, genetic disorders, or microorganisms. Microorganisms that cause sickness are known as pathogens.? What is a pathogen?Pathogens are any microorganisms that cause cell death and disease and is seen as foreign and in a part of the body that they normally are not found. All pathogens have antigens on the surface of their cells, such as receptors or carbohydrates, which are features recognized by the human body's immune mon PathogensViruses381000017526000Viruses are infective agents that do not carry out any life processes (cannot eat or respire). Viruses only reproduce inside another living cell and can cause diseases. Viruses are classified according to the living things they infect (plant virus infects plants, animal virus infects animals, bacterial virus infects bacteria). Viruses enter body cells, hijack their organelles, and turn the cell into a virus making-factory. The cell will eventually burst, releasing thousands of viruses to infect new cells in a process called the Virus Reproduction Cycle.39909751270000Parts of a Virus:Capsid “the head” is a protein protective head that gives the virus its characteristic shape.Nucleic acid is found inside the capsid headTailcenter41402000Virus Reproduction Cycle:What is a Virus? - Video: can we do to prevent viral infections?A vaccine is a biological preparation that provides active acquired immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing micro-organism and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it, and keep a record of it, so that the immune system can more easily recognize and destroy any of these micro-organisms that it later encounters. Vaccines can be prophylactic (example: to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g., vaccines against cancer are also being investigated).BacteriaWhat does a bacteria look like?center26987500Bacteria are single celled living organisms that can reproduce independently on their own. Bacteria can inhabit almost every environment on earth (soil, water, ice, high temperatures or other living organisms).Can eat many things (starch, sugar, iron…)Most are harmless to humans (Those breaking down organic waste or aiding in food production).Note that bacteria are much bigger than viruses312674026606500A common name of a bacterium that is often referred to is E. Coli or more formally known as Escherichia coli. This bacterium is common and plentiful in all of our digestive tracts. Although plentiful, this does not mean that we will be sick. These bacteria are technically outside the body and aid in digesting material that we cannot. Only if E. Coli are introduced in an unnatural manner can they break through the first line of defense and harm us. Bacteria Video: Bacteria Come in many different shapes:-16192532131000How do antibiotics work against infections?Antibiotics can be used to treat bacterial infections. Antibiotics are ineffective in treating illnesses caused by viruses. Antibiotics treat specific bacteria. Overuse or misuse of antibiotics can lead to drug-resistant bacteria known as superbugs. It is important that antibiotics are taken properly and for the duration of the prescription. If antibiotics are stopped early, the bacteria may develop a resistance to the antibiotics and the infection may occur.What are some ways in which contagious diseases are spread? How do diseases spread? – Video: Sexual transmission?-?transmission of an infection through sexual contact, including intercourse.Airborne transmission?-?transmission of an infection through inhaling airborne droplets of the disease, which may exist in the air as a result of a cough or sneeze from an infected person.Blood-borne transmission?-?transmission of an infection through contact with infected blood, such as when sharing hypodermic needles.Direct contact transmission?-?transmission of an infection through a direct body surface-to-body contact with an infected person.Insect-borne transmission?-?transmission of an infection through insects, such as mosquitoes, which draw blood from an infected person and then bite a healthy person.Food-borne transmission?-?transmission of an infection through consuming contaminated food.Water-borne transmission?-?transmission of an infection through contact with contaminated water.Other mechanisms can transmit a diseasecenter1333500How Does the Body Defend itself from infections? There are three lines of defense our body uses to defend itself against pathogens:Mechanical Defense LeukocytesAntibodiesMechanical DefenseThe first line of defense is the mechanical defense that serves as a shield against bacteria and viruses. These include:BarrierFunctionSkintough, durable, and flexible layer layers of dead cells at the skin’s outer surface that very few pathogens can penetrateconstant cell shedding removes adhering pathogensOil and Sweatglands at the surface of the skin produce an acidic environment pH 5-6 that kills or repels many pathogensEar WaxTraps pathogens and dirt particlesBody Secretions(Nasal Mucus, Tears, Saliva, Sweat) These secretions lubricate and wash bacteria out of eyes, nose and mouth Also contain a bacteria killing enzyme called LYSOZYME which breaks down the cell wall of many bacteriaMucus and CiliaMucus traps pathogens in the nose and throat so that they can be swept away by cilia and removed by sneezing or swallowing to the stomach.Digestive AcidsHCl(stomach acid) and digestive enzymes kills most pathogens that enter the stomachVomitingRemoves toxic and infectious agents from stomachUrinationSlightly acidic, flushes out urinary systemDefecationRemoves pathogens from intestinal tractResident BacteriaControls harmful organisms when beneficial bacteria create competition with harmful bacteria, and produce effects that alter the body’s pHLeukocytesThe second line of defense is the white blood cells/ leukocytes.114300011938000If invaders actually get within the body, then your white blood cells (WBCs) begin their attack. White blood cells travel in the bloodstream and react to different types of infection caused by bacteria, viruses or other pathogens. White blood cells will enter the body’s tissues if invaders are detected. Neutrophils engulf bacteria and destroy them with special chemicals. Eosinophils and monocytes also work by swallowing up foreign particles in the body. Basophils help to intensify inflammation (swelling).?AntibodiesThe third line of defense is made up of antibodies.17907008763000Antibodies are proteins that are created in your body to attack specific antigens or infections that are made to attack. Antibodies latch onto, damage, clump and slow foreign particles. Each antibody binds only to one specific binding site known as the antigen. White blood cells engulf invading particles and break them up. They show particle pieces to the T-cell lymphocytes who identify the pieces and find specific B-cells (another type of lymphocyte) to help. B-cells produce antibodies that are equipped to find that specific piece on a new particle and attach. Some antibodies remain in the blood after the battle, providing immunity from future attacks by the same type of infection. Therefore at this stage, the body has acquired immunity form the disease. New particles take longer to identify, and a person remains ill until a new antibody can be crafted. Old particles are quickly recognized, and a person may never become ill from that invader again. This person is now immune.The Inflammatory ResponseWhat is the purpose?The primary physical effect of the inflammatory response is for blood circulation to increase around the infected area. In particular, the blood vessels around the site of inflammation dilate, permitting increased blood flow to the area. Gaps appear in the cell walls surrounding the infected area, allowing the larger cells of the blood, i.e. the immune cells, to pass. As a result of the increased blood flow, the immune presence is strengthened. All of the different types of cells that constitute the immune system congregate at the site of inflammation, along with a large supply of proteins, which fuel the immune response. There is an?increase in body heat, which can itself have an anti-biotic effect, swinging the balance of chemical reactions in favour of the host. The main symptoms of the inflammatory response are as follows.The tissues in the area are?red?and?warm, as a result of the large amount of blood reaching the site.The tissues in the area are?swollen, again due to the increased amount of blood and proteins that are present.The area is?painful, due the expansion of tissues, causing mechanical pressure on nerve cells, and also due to the presence of pain mediators.Once the inflammatory process has begun, it continues until the infection that caused it has been eradicated. Phagocytes continue to consume and destroy bacteria, the acquired immune system binds and disposes of harmful toxins.?Pus?is produced, pus being the?debris?that is left over from the battle between the invader and the immune system. The colour of the pus depends on the organism causing the infection.How does the inflammatory response end?Ideally, the inflammatory response should only last for as long as the infection exists. Once the threat of infection has passed, the area should return to normal existence.The actual process by which the inflammatory response ends is now only beginning to be understood. The key element is a phenomenon known as "Apoptosis".When cells of the body die in a normal fashion, e.g. by being irreparably damaged or by being deprived of nutrients, this is known as?Necrotic?death. Recently, research has shown that cells can also be killed in another way, i.e. by "committing suicide". On receipt of a certain chemical signal, most cells of the body can destroy themselves. This is known as?Apoptotic?death. There are two main ways in which cells can commit?Apoptosis.By receiving an?Apoptosis?signal. When a chemical signal is received that indicates that the cell should kill itself, it does so.By not receiving a "stay-alive" signal. Certain cells, once they reach an activated state, are primed to kill themselves automatically within a certain period of time, i.e. to commit?Apoptosis, unless instructed otherwise. However, there may be other cells that supply them with a "stay-alive" signal, which delays the?Apoptosis?of the cell. It is only when the primed cell?stops?receiving this "stay-alive" signal that it kills itself.The immune system employs method two above. The immune cells involved in the inflammatory response, once they become activated, are primed to commit Apoptosis.?Helper T cells?emit a?stay-alive signal, and keep emitting that signal for as long as they recognise foreign antigens in the body, prolonging the inflammatory response. It is only when the infection has been eradicated, and there is no more foreign antigen that the?helper T cells?stop emitting the stay-alive signal, thus allowing the cells involved in the inflammatory response to die off.If foreign antigen is not eradicated from the body, or the helper T cells do not recognise that fact, or if the immune cells receive the stay-alive signal from another source, then?chronic inflammation?may develop.B-cells and T-cellsWhat do T-cells and B-cells do?These cells are highly specialized defender cells – different groups of cells are tailored to different germs. When your body is infected with a particular germ, only the T- and B- cells that recognize is will respond. These selected cells then quickly multiply, creating an army of identical cells to fight the infection. Special types of T- and B- cells ‘remember’ the invader making you immune to a second attack.How do you recognize invaders?Your T- and B-cells recognise invaders by the shape of molecules - antigens - on their surfaces. Your immune system can produce a T- and B-cell to fit every possible shape. However, any T- or B-cell that recognised molecules found on your cells were destroyed while you were growing in the womb, to prevent them from attacking your own body. But you were left with millions of others, one for every foreign antigen you might ever encounter.What is so special about your T-cells?Having recognised the invader, different types of T-cell then have different jobs to do. Some send chemical instructions (cytokines) to the rest of the immune system. Your body can then produce the most effective weapons against the invaders, which may be bacteria, viruses or parasites. Other types of T-cells recognise and kill virus-infected cells directly. Some help B-cells to make antibodies, which circulate and bind to antigens.What is so special about your B-cells?With the help of T-cells, B-cells make special Y-shaped proteins called antibodies. Antibodies stick to antigens on the surface of germs, stopping them in their tracks, creating clumps that alert your body to the presence of intruders. Your body then starts to make toxic substances to fight them. Patrolling defender cells called phagocytes engulf and destroy antibody-covered intruders.Types of ImmunityNatural Immunity: Resistance you are born with. It is your body’s natural defense against disease.Acquired Immunity: Immunity that you develop during your lifetime and this immunity involves the third line of defense. This is not present at birth. There are three types of acquired immunity.Natural Active Acquired Immunity: Natural Active Acquired immunity occurs when a body forms antibodies that will seek and destroy specific germs. These antibodies remain in the body protecting the body from future attacks of the same germ. Artificial, Active Acquired Immunity:Artificial, active acquired immunity occurs when the body is stimulated by a vaccine to produce antibodies. Vaccination/immunization is a treatment in which the body receives a modified strain of the disease (dead or weakened). The body is stimulated by this dose and produces antibodies that remain in the blood, protecting the body from future attacks by that particular germ. This results in long-term immunity.Artificial Passive Acquired immunity:Artificial Passive Acquired immunity occurs when the body receives an injection of antibodies that will protect the body from an attack by a specific germ. This occurs when another individual’s antibodies is doing the work of fighting off an infection. This is considered short-term immunity. Anti Vax Video: Disorders of the Immune SystemALLEGIES and ANAPHYLAXIS (ANAPHYLACTIC SHOCK)Allergies affect millions of people who sneeze and cough with itchy watery eyes and runny nose around pollen, dust, cats and dogs. An ALLERGY is an over-sensitivity to non-harmful antigen called an ALLERGEN.What is happening?Allergic reactions or anaphylactic shock occur when Allergens trigger B-cells to produce antibodies called “allergic antibodies”.“Allergic antibodies” inappropriately attach and induce mast cells to produce histamine. Histamine triggers the inflammatory response, which dilates local blood vessels, which results in more liquid filling the eyes and nose resulting in runny eyes and runny nose.Antihistamine: How do they work?Antihistamine drugs reduce allergy symptoms by neutralizing or blocking the action of histamine released from mast cells, thereby minimizing the symptoms of an allergic reaction.Most allergies are a nuisance, but some allergies are life-threatening. For example when some people eat peanuts, or are stung by a bee, they suffer a sudden, dramatic drop in blood pressure and have difficulty breathing. This condition is called ANAPHYLACTIC SHOCK, and can be a fatal condition. Self-injections from an epi-pen of EPINEPHRINE (adrenaline) will counter act the allergy’s symptoms and restore blood pressure, and breathing rates, temporarily. Scientists do not know why some people have allergies while others do not, but allergies tend to run in families, suggesting that they have a genetic basis. Studies also show that breast fed infants are less prone to allergies later in life, compared to infants fed on baby formula.AUTOIMMUNE DISEASES:Autoimmune diseases are caused by the immune system attacking “self” cells when it cannot always distinguish between self and non-self-antigens.Examples of autoimmune disease include: Lupus, rheumatoid arthritis, and multiple sclerosis.Lupus:Occurs when the body makes antibodies that react with its own tissue. Symptoms can include: fever, weakness, weight loss, anemia (destroying own red blood cells) butterfly shaped rash on face.Rheumatoid Arthritis:Occurs when the body makes antibodies that react with its own tissue. Immune system attacks cartilage and bone joints, causing damage and painful inflammation.Multiple Sclerosis:Occurs by affecting the central nervous system. T cells attack the myelin sheaths that cover the axons of some neurons (nerve cells). This affects the transmission of nerve impulses.Symptoms include: fatigue, tingling, numbness. More advanced cases may interfere with walking, talking, memory, and concentration.Scientists have not determined the exact causes of autoimmune diseases. Evidence points to genetics, exposure to toxic chemicals, and certain viruses.Medicines for autoimmune diseases generally replace the destroyed “self” molecules, suppress the immune response or treat specific symptoms.ACQUIRED IMMUNE DEFICIENCY: AIDSHIV is deadly because it destroys the immune system, leaving the body unable to defend itself against pathogens and certain cancers. Both antibody immunity (B cells) and cellular immunity (T cells) are impaired. Therefore the immune deficiency is acquired from the environment not inherited.Death usually occurs from another infection, such as pneumonia, or certain types of cancer.HIV/AIDS VIDEOS:P1: Understanding HIV and Aids P2: When HIV becomes AIDS P3: Testing for HIV P4: Treatment for HIV/AIDS BODY’S REACTION TO ORGAN TRANSPLANTS:An organ transplant replaces a damaged organ or part or an organ with a healthy organ or tissue. Common organ transplants involve kidneys, liver, cornea, and skin.The transplanted organ is identified as nonself tissue and triggers the immune response.In all transplants, medications are necessary to suppress the immune response to foreign organs/tissues, and decrease the possibility of rejection.However decreasing the patient’s immune system increases the risk of infection.Successful transplant recipients lead full normal, active lives.WHAT CAN YOU DO TO KEEP YOUR IMMUNE SYSTEM HEALTHY? 1.Reduce the number of pathogens that enter the body by:Washing hands frequently throughout the day, and especially before and after bathroom use. 2.Provide your body with adequate nutrients to maintain the immune systemeat a balanced diet3.Reduce StressImmune system is especially affected by the body’s response to stress. Chemicals released during stress, can suppress the immune system making you more vulnerable to disease. Learning to cope with stress will help your immune system function better.Bio30SQUESTIONS ON IMMUNITY: Name any three ways diseases can be spread.What defenses does the body have that resist entry of disease organisms? Explain. Compare physical and chemical Barriers.tough, durable, and flexible layer layers of dead cells at the skin’s outer surface that very few pathogens can penetrateconstant cell shedding removes adhering pathogensglands at the surface of the skin produce an acidic environment pH 5-6 that kills or repels many pathogensTraps pathogens and dirt particles(Nasal Mucus, Tears, Saliva, Sweat) These secretions lubricate and wash bacteria out of eyes, nose and mouth Also contain a bacteria killing enzyme called LYSOZYME which breaks down the cell wall of many bacteriaMucus traps pathogens in the nose and throat so that they can be swept away by cilia and removed by sneezing or swallowing to the stomach.HCl(stomach acid) and digestive enzymes kills most pathogens that enter the stomachRemoves toxic and infectious agents from stomachSlightly acidic, flushes out urinary systemRemoves pathogens from intestinal tractControls harmful organisms when beneficial bacteria create competition with harmful bacteria, and produce effects that alter the body’s pHExplain the body’s second line of defense: Inflammatory response.When is the body’s third line of defense used? Describe it.In what two ways does fever help the body fight against infection?Compare specific and non-specific immunity.Explain what an antigen is?What is the function of antibodies? Compare and contrast the body’s primary response to the body’s secondary pare active immunity to passive immunity. Determine if the following situations will lead to active or passive immunity:a boy has the mumps ____________________________an infant receives antibodies against measles in its mother’s milk.___________________________________________________a woman who has been exposed to hepatitis is given a shot of gamma globulin.___________________________________________________Ms. Morris takes medication for her cold symptoms.____________________________________________________Ms. Morris got the flu shot this year._____________________________________________________How do vaccinations provide the body with immunity?Why does exposure to the influenza virus not provide immunity to other viruses?What is the function of a booster shot? ................
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