Presentation on theme: "The immune system HBS3B. Revision question Using a diagram, explain the structures that comprise a synovial joint and their functions."— Presentation transcript:
The immune system HBS3B
Revision question Using a diagram, explain the structures that comprise a synovial joint and their functions.
Synovial joints Synovial capsule surrounds the joint and helps stabilise it and hold it all together Synovial membrane is thin and smooth, to reduce friction, and secretes synovial fluid Synovial fluid is thick and sticky, and acts as a lubricant for the joint Articular cartilage provides a smooth surface to reduce friction as the bones move across each other Articular disc are cartilaginous discs which act as shock absorbers Bursae are fluid filled sacs which act as shock absorbers Accessory ligaments join the bones and keep them together
The nervous and endocrine systems Label the structures List the hormones and their effects
The nervous and endocrine systems Label the structures List the hormones and their effects cerebrum cerebellum hypothalamus pons pituitary gland medulla spinal cord
The immune response The specific protection the body has against a particular pathogen or foreign chemical results from a process called the immune response There are two components of the immune response – the humeral or antibody mediated response and the cell mediated response Both rely on the recognition of antigens. An antigen is anything that triggers an immune response. Most antigens are proteins, and are either toxins, protein coats around viruses, or parts of cell walls or membranes. These act like labels that the white blood cells can read to tell whether it belongs in the body or not.
The immune response
Humeral response This response involves B- lymphocytes or B-cells. This response provides resistance to bacteria, viruses and bacterial toxins B-cells detect free antigen Helper T-cells detect macrophage-presented antigens and stimulate B-cells The B-cells then begin to divide or clone Two types of B-cells are then produced – Plasma cells make free antibody Memory cells store information about antigen for future response (immunity)
Antibodies Antibodies are specific for particular antigens. This means that they fit the antigen like a lock an key Antibodies work by attaching to an antigen and: preventing viruses from entering cells inactivating toxins destroying cell walls causing agglutination reducing solubility attracting white blood cells increasing phagocytosis activating complement
Phagocytosis Macrophages engulf and destroy foreign invaders. This process is made easier when the pathogen is coated with antibody
Cell mediated response This response involves T-lymphocytes or T-cells. This response provides resistance to intracellular phase of bacteria and viruses as well as resistance to fungi and parasites, rejection of transplants and fighting cancer cells T-cells detect free antigen Helper T-cells detect macrophage- presented antigens and stimulate other T-cells The T-cells then begin to divide or clone Four types of B-cells are then produced – Helper cells aid in recognition and activate other lymphocytes Killer-cells (cytolytic cells) produce cytotoxic chemicals which kill foreign cells Memory cells store information about antigen for future response (immunity) Suppressor cells stop the immune process when the antigen has been removed
Specific versus non-specific responses Specific defences The immune response is said to be specific, because it only responds to a specific antigen. Each pathogen carries a certain marker (usually proteins) or has a certain shape - this is called an antigen. The lymphocytes recognise the antigens on its own body cells as self. Any other antigens are foreign, and to be destroyed. The immune response produces antibodies and killer lymphocytes targeted against one, and only one, antigen. This usually results in the destruction of this antigen, and a memory, or immunity, for this particular antigen, due to the presence of memory cells (both B and T cells). Each new antigen must be recognised, and a new set of antibodies and killer t-cells manufactured against it. Non-specific defences Non specific responses react to any pathogen. They include external defences including physical barriers & traps skin - water proof, impermeable barrier, mucous membranes – barrier, mucus, ear wax - sticky trap, hairs - trap pathogens, cilia in respiratory tract - catch & move pathogens up to pharynx where they are swallowed, tears, sweat, urine - wash away pathogens chemical traps & protection lysosome - enzyme in tears kills bacteria, cerumen - enzyme in ears kills bacteria, sebum - enzyme on skin kills bacteria, acidic secretions in stomach, urine, vagina prevent growth of pathogens, digestive enzymes in saliva, stomach & intestine kill bacteria), friendly bacteria on skin prevent pathogens from multiplying, Internal protection includes inflammation and non- specific phagocytosis.
Immunity Immunity is protection from disease due to presence of antibodies Active immunity – have memory cells and can make own antibodies Passive immunity– have antibodies, but not memory cells so can’t make own antibodies (antibodies come from someone else) Natural immunity– no human intervention is required, Artificial immunity– human intervention is required. Active Natural – get disease and make memory cells. Active artificial – vaccination to stimulate memory cell production Passive natural – antibodies pass from mother to baby (via placenta or milk). Passive artificial – given injection of antibodies/antitoxins..
Vaccination Immunization or vaccination depends on using an antigen prepared in a relatively harmless form as the primary stimulus to develop immune memory (ie presence of memory cells). If the person is subsequently infected they have the ability to produce large amounts of antibody very quickly. The ready made anti toxins or antibodies used to provide passive immunity in humans are usually made by injecting an animal (usually horses) with antigen, then collecting the blood and taking out the antibodies they made. This provides passive immunity that lasts for a short time. Vaccines are preparations of antigens used to stimulate the immune system. There are four main types of vaccines: i) living attenuated – pathogen weakened by giving to other animals/growing in tissue culture eg measle, mump, polio ii) dead microorganisms – pathogen killed by heat/radiation eg cholera, typhoid iii) toxoids – fake/inactivated toxin eg cholera, typhoid iv) Sub-units -antigens made by recombinant DNA (genetic engineering) – antigen only so no possibility of getting disease eg Human papilloma virus, hepatitis B
Vaccines Some problems seen with vaccinations are side effects eg allergic reactions, people actually getting the disease, and short effectiveness of some older vaccines so re-immunisation is needed. Methods used to reduce the virulence or possibility of side effects of vaccines are to use recombinant DNA technology to reduce virulence of pathogens in a vaccine, or to produce vaccines containing harmless bacteria genetically engineered to produce the antigen or only the antigen (not the whole pathogen). Vaccines can be delivered by a number of methods including injection, by mouth, by nasal spray, by skin patches. A new area of research is genetically engineered plants to act as vaccines. Herd immunity refers to immunity levels within a population. If enough people are immune (through natural or acquired immunity) disease transmission is slowed. Some risks and concerns about the production of vaccines include the side effects (eg allergic reactions), the risk of cross species disease introduction and effects of preservatives or added chemicals in the vaccines. Some people choose not to be vaccinated or have their children vaccinated because of concerns about these risks, religious beliefs or ignorance about the benefits of vaccination or prevalence of the disease being vaccinated against.
Primary and secondary response What happens to the amount of antibody in the blood in response to an initial attack by a pathogen? This initial increase is called the p_________ response. Describe what happens, at a second pathogen attack, to the amount of antibody. Compare this secondary response with the primary response. Why does a second infection result in a quicker and stronger response? Explain why booster doses of vaccines are needed in some immunization schedules
Primary and secondary response What happens to the amount of antibody in the blood in response to an initial attack by a pathogen? It takes ~7 days to respond, then increases over 10 days, before gradually falling This initial increase is called the primary response. Describe what happens, at a second pathogen attack, to the amount of antibody. It takes ~3 days to respond, then increases more rapidly and to a higher level, and its fall is lower. Compare this secondary response with the primary response. Its faster and stronger & the fall is less Why does a second infection result in a quicker and stronger response? There are memory cells present, so recognition and response is faster Explain why booster doses of vaccines are needed in some immunization schedules Over time antibody levels fall. If they fall to far you will not have enough antibodies to protect you from the disease. A booster stimulates more lymphocytes & a higher antibody level
Antibiotics and antivirals Antibiotics are chemicals that kill bacteria or other microbes. They work by destroying cell structures or interfering with metabolic processes. Examples include penicillin, amoxicillin, streptomycin Antibiotics are only effective against bacteria (and some protozoa and fungi) Viruses are not affected by antibiotics as they are not cells, therefore can not be affected by chemicals that destroy cell structures or functioning. One problem with antibiotic use is antibiotic resistance. This is a problem because bacteria that were once considered harmless are now capable of causing serious disease or death, as they are not killed by commonly used antibiotics. Some reasons why resistance is increasing include overuse of antibiotics in medicine (eg for treating viral infections) and agriculture (especially in food animals) and people not finishing the course of antibiotics they were given when sick Viral diseases can be treated by chemicals called antivirals Examples include zidovudine (AZT) and interferon. These act by interfering with the virus’s ability to invade cells or increasing the immune systems effectiveness