THE IMMUNE SYSTEM Students should be able to:Describe the role of the blood in defending the bodyExplain how the principles of immunization are used tocontrol communicable disease
T E R M IN O L O G Y• A N T I B I O T I C S : A drug used to treat infections caused by bacteria and other microorganisms (inhibits growth or destroys). e.g. penicillin, streptomycin, tetracycline• A N T I G E N : A toxin or other foreign substance that induces an immune response in the body, esp. the production of antibodies.• A N T I B O D Y : A blood protein produced in response to and counteracting a specific antigen
• I M M U N I T Y : The ability to resist a particular toxin by the action of specific antibodies.• I M M U N I Z A T I O N : the act of making immune (especially by inoculation, i.e. taking a vaccine as a precaution against contracting a disease).• V A C C I N E : A substance used to stimulate the production of antibodies and provide immunity against one or several diseases, prepared from the causative agent of a disease, its products, or a synthetic substitute, treated to act as an antigen without inducing the disease.
FIRST LINE OF DEFENSE• Goal: to stop pathogens from entering the body Skin – acts as a barrier to invasion Sweat – has chemicals which can kill different pathogens. Tears - have lysozyme which has powerful digestive abilities that render antigens harmless. Saliva – also has lysozyme. Mucus - can trap pathogens, which are then sneezed, coughed, washed away, or destroyed by chemicals. Stomach Acid – destroys pathogens
SECOND LINE OF DEFENSE• If a pathogen is able to get past the bodys first line of defense, and an infection starts, the body can rely on its second line of defense.• First there is a non-specific response (phagocytosis) followed by an INFLAMMATORY RESPONSE.
Inflammation causes:ii.Redness - due to capillary dilation resulting in increased blood flowiii.Heat - due to capillary dilation resulting in increased blood flowiv.Swelling – due to passage of plasma from the blood stream into the damaged tissuev. Pain – due mainly to tissue destruction and, to a lesser extent, swelling.
THIRD LINE OF DEFENSE• Sometimes the second line of defense is still not enough and the pathogen is then heading for the bodys last line of defense, the immune system.• The immune system recognizes, attacks, destroys, and remembers each pathogen that enters the body. It does this by making specialized cells and antibodies that render the pathogens harmless.• Unlike the first line and second line defense the immune system differentiates among pathogens.• For each type of pathogen, the immune system produces cells that are specific for that particular pathogen.
• The Immune System includes all parts of the body that help in the recognition and destruction of foreign materials.• Parts of the immune system: white blood cells(phagocytes and lymphocytes) bone marrow lymph nodes tonsils thymus spleen
TYPES OF IMMUNITY P A S S IV E A C T IV E• Source: It is developed • Source: It is developed by when ready-made an individual’s own cells in antibodies are inoculated response to an infection or from outside. a vaccine.• Side effects: It may cause • Side effects: It has no side reaction. effects.• Period of relief: It provides • Period of relief: It provides immediate relief. relief only after long• Period of effectiveness: It period. is short lived • Period of effectiveness: It is long lasting.
• The natural passive immunity occurs, when the maternal IgG type antibodies is passed to the foetus through the placenta. It is very much helpful in the initial 6 months of the infant’s life when the immune system is still developing.• In the artificial passive immunity, we are introducing immunoglobulin or pre formed animal based antibodies (antiserum) to a non immune person. This can be used, following exposure, to a pathogen.
• It is named as naturally acquired active immunity because, the person develops the full fledged infection to the organism and later finds himself resistant to that organism.• In the artificial acquired active immunity, the patient is introduced with an organism (usually attenuated) along with substances to activate the immune response.
DISEASES OF THE IMMUNE SYSTEM• HAY FEVER: is your immune systems response FEVER to foreign material in the air you breathe.• Hay fever usually refers to allergies to outdoor, airborne materials such as pollens and molds.• A particular kind of antibody, IgE is released causing very sensitive reaction to the allergens.• Histamine is produced resulting sneezing, difficulty breathing, runny nose.• Antihistamines and inhalers relieve symptoms.
• ASTHMA: is a disorder that causes the airways ASTHMA of the lungs to swell and narrow, leading to wheezing, shortness of breath, chest tightness, and coughing.