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| 1443049055 | Lines of defence | Physical barriers Immune response | 1 | |
| 1443049056 | Physical barriers | skin, keeping micro-organisms from entering body | 2 | |
| 1443049057 | Immune response | once the pathogen is identified, a specific response from WBC takes place Phagocytosis | 3 | |
| 1443049058 | Non specific mechanisms | Natural barriers, skin, skin flora, blood clotting - seals wounds Ciliated mucus membranes, lysozyme enzyme and stomach acid Resistance to disease depends on the general health and diet Vitamin C deficiency leads to weakened connective tissue, causing open wounds Skin flora - population of harmless micro-organisms that live on the skin surface. Protect us by competing with pathogenic bacteria for nutrients Localised defence - inflammation and phagocytosis | 4 | |
| 1443049059 | inflammation | Caused by damage to body's tissues Pain, redness, heat and swelling Functions: destroys cause of infection, confines infection to a small area limiting the effects on the body, replaces or pairs damaged tissue | 5 | |
| 1443049060 | 3 stages of inflammation | Increase in diameter and permeability of blood vessels in damaged area → increases blood flow therefore allowing defence cells to reach the area. → blood clots form in damaged blood vessels WBC (phagocytes) arrive, start destroying microbes by phagocytosis → an abscess will start to form after a few days, which is pus - contains dead phagocytes, damaged tissues, body fluids New cells replace the dead tissues | 6 | |
| 1443049061 | phagocytosis | Phagocyte attaches itself onto the bacterium's surface Engulfs pathogen into a vesicle Lyzosome moves towards this vesicle. Lyzosomes contain Lyzozymes, the digestive enzyme The two vesicles fuse, causing enzyme to digest the pathogen. Fragments of the antigen are presented on the surface of the macrophage Soluble products are absorbed into the phagocyte. Leftover fragments are released by exocytosis | 7 | |
| 1443049062 | Specific mechanisms | For individual forms of infection | 8 | |
| 1443049063 | Antigens | Substance that triggers the formation of antibodies, or reacts with antibodies already present Complex molecules usually made out of proteins or polymers Self antigens - occur on surface of cells of the body Non self-antigens - foreign organisms Non-self antigens triggers production of antibodies | 9 | |
| 1443049064 | Antibodies | Glycoproteins - blood proteins called immunoglobulins Y shaped molecule, made out of 2 large 'heavy' polypeptide chains and 2 light polypeptide chains There are 2 variable antigen-binding sites Different for each antibody Recognise and attach to a specific antigen Produced by lymphocytes in the presence of the specific antigen | 10 | |
| 1443049065 | Cell-mediated immune response | Involves T lymphocytes Recognise and attack a particular type of antigen Lymphocytes mature in thymus gland. Become "immunologically competent", capable of synthesizing new receptor molecules, incorporated into plasma membrane. Circulate in the blood and body fluids. Macrophages engulf pathogens having non-self antigens. The macrophages then present these antigens on their membrane. Binding sites on the surface of a T lymphocyte recognize and fit with the antigen T lymphocytes triggered and rapidly multiply. Divide by mitosis. Produce clones of T lymphocyte that recognise the antigen as being non-self Each cell in the clone can attach to the complementary antigen and destroy it Clone can differentiate | 11 | |
| 1443049066 | Humoral immune response | Involves B lymphocytes Attack and destroy antigen on non-self-micro-organism , by producing antibodies - Antigens in the cell membrane of a macrophage are recognised by B-cells - B-cells are triggered when specific binding sites on their surface attach to the antigens - Activated cells divide rapidly by mitosis, forming a clone of the plasma cells in the lymph node. These cells produce antibodies or memory cells - Antibodies circulate and bind with the specific antigen and destroy it. Immediate defence against infection. (primary immune response) - Only live for a few days, but can produce and secrete vast quantities of antibodies. Memory cells can live for a very long time. If that antigen is encountered again, the memory cells will recognise it and stimulate the production of antibodies. (secondary immune response) | 12 | |
| 1443049067 | Antibodies and antigens | Antibody becomes attached to antigen at the binding site Causes antibody to change from T shape to Y shape Exposes part of the antibody to substances in the blood plasma - Antibodies and antigens form immune complexes on the bacterial surface, making the bacteria clump together. - Phagocytes can engulf the bacteria, by phagocytosis | 13 | |
| 1443049068 | Natural Passive Immunity | May be due to transfer of antibodies from mother to foetus across the placenta Or from mother to new-born offspring via colostrum (the first secretion of the mammary gland) Temporary, no memory cells produced | 14 | |
| 1443049069 | Natural Active Immunity | Exposure to infection Body makes its own antibodies and specific memory cells Long lasting | 15 | |
| 1443049071 | Artificial Passive Immunity | Injection of ready-made antibodies No memory cells - temporary Preventative measure for diseases that are difficult to immunise against e.g. tetanus and diphtheria Treatment for diseases whereby an infection has already occurred and is too dangerous to leave to the body's immune system e.g. rabies Short lived because injected antibodies are non-self and are destroyed | 16 | |
| 1443049073 | Artificial Active Immunity | Vaccination Lymphocytes recognise non-self Injecting a dead or inactive form of the pathogen Causes stimulation of antibodies and memory cells Acquires immunity | 17 | |
| 1443049075 | Primary latent period | Antigen is detected by B lymphocytes Activated cells divide through mitosis Produce antibodies and some memory cells | 18 | |
| 1443049077 | Primary response period | Antibody concentration increases and then decreases | 19 | |
| 1443049079 | Secondary response | If antigen is reintroduced or if it persists Lower level of antigen with a shorter latent phase Higher concentration of antibodies produced Triggers the same events as the primary response but much quicker Memory cells are activated to produce plasma B cells producing the specific antibody which remain for a longer time | 20 | |
| 1443049080 | Effectiveness of vaccination programmes | The greater the proportion of the population vaccinated, the greater the effectiveness of the programme International co-operation is required to reduce global problems Rate of mutation will affect the effectiveness too: A low mutation rate means that the vaccine can be effective over longer periods of time, whereas the influenza virus cannot be vaccinated against due to the high mutation rates and lack of resistance in the population and lack of long-term vaccination A few cases of vaccination in "childhood" diseases have caused a few side effects. This has reduced the number of people being vaccinated, increasing the incidence of disease, and therefore increasing the risk of contact. Public information and education are required to allow people to make rational and informed choices. Increased travel increases risk of infections spreading globally Influenza is spread through droplet infection, meaning it is difficult to control We must reduce the reservoirs of birds or animals who are not vaccinated. For example, only teenage girls were meat to get the rubella vaccination, however the boys would be a reservoir for the disease, therefore all are vaccinated against rubella | 21 | |
| 1443049081 | Effects of HIV infection | AIDS is caused by HIV. HIV is a retrovirus, meaning that it uses its RNA to produce single strand of DNA (copy DNA) inside the host cell Transmitted through blood or semen, through cuts in the skin or an infected hypodermic needle. May have no symptoms or may have a short lived illness when they are first infected. Virus attacks the T-helper cells in the body's immune system Virus can remain latent for many years Starts to replicate and destroys host cell Reduces number of T cells HIV reduces body's ability to fight off disease Immune system weakens, infections start to take hold Symptoms are vast and not always due to directly the HIV Cancer, weight loss, weakness, fever, diarrhea, deteriorating brain function, pneumonia (rare form) HIV antibodies present in blood T helper cell is low Clinical AIDS | 22 |
