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Immune System Notes.notebook April 16, 2014 Immune System - fights off infection and pathogens (1) *Skin is body's first line of defense -blocks invading pathogens (2) -BUT skin has some openings (eyes, nose, mouth, etc.) so these areas need extra protection. -secretes oil and sweat making it hard for pathogens to survive. (3) * Second line of defense:mucous membranes use hair-like cilia that are covered in a sticky liquid to try and trap pathogens (4) *Once a pathogen gets in, immune system relies on the (5) circulatory system to send chemical signals to coordinate an attack by transporting specialized cells to the site of infection. *The immune systems' warriors are proteins and WBCs. 1 Immune System Notes.notebook April 16, 2014 White Blood Cells (WBC) -their job is to find and kill pathogens -6 types work together (7) -different type(s) are used depending on the pathogen *Basophils - make chemicals that cause inflammation in the bloodstream *Mast Cells - makes chemicals that cause inflammation in other body tissues *Neutrophils - engulfs pathogens and foreign invaders; phagocyte *Macrophage - engulfs dead or damaged body cells and some bacteria: phagocyte *Lymphocyte - destroys infected body cells or produces proteins that inactivate pathogens; 2 types -T cells: destroy body cells that are infected with pathogens -B cells: produce proteins that inactivate pathogens that have not yet infected a body cell *Eosinophil - injects poisonous packets into parasites, such as protozoa (8) Phagocytes: cells that destroy pathogens by surrounding and engulfing them (9) 2 Immune System Notes.notebook April 16, 2014 Proteins (10) -3 different Proteins help the immune system (complement, antibodies, interferons) Complement -made by WBC and organs (11) -weaken a pathogen's cell membrane -causing it to become hypotonic and burst -attracts phagocytes to infected area -cause microbes to stick to walls of blood vessels -easy to find and destroy by phagocytes Antibodies -made by B cells, destroy cells in 1 of 3 ways (11) a) might make pathogen ineffective by binding to the pathogens membrane proteins b) might cause pathogens to clump -makes phagocytes job easier c) activate complement proteins that weaken the pathogen's cell membrane (11) Interferons -produced by body cells that are infected by a virus a) cells release interferons that then stimulate uninfected body cells to produce enzymes that will prevent viruses from entering/infecting them b) some stimulate an inflammation response 3 Immune System Notes.notebook April 16, 2014 Immunity prevents a person from getting sick from a pathogen (12) -can be immune to a pathogen, won't get sick if it invades your body -Example: individuals who are heterozygous for sickle cell-malaria resistance -2 types of immunity: passive and active Passive: immunity that occurs without the body undergoing an immune response (13) -Can be genetic (transferred through generations via DNA) or from mother to child through umbilical cord or mother's milk Active: immunity that your body produces in response to a specific pathogen that has infected or is infecting your body (13) -Acquired immunity - occurs after your immune system reacts to a pathogen invasion, keeps your from becoming sick from a particular pathogen more than once -Vaccines are given to help the body reach an acquired immunity from some pathogens before they have the chance to attack the body -Why don't we get an acquired immunity from a common cold/flu? -viruses mutate very quickly forming new strains BUT you immune system destroys repeat invaders before you get sick...You just don't know it! 4 Immune System Notes.notebook April 16, 2014 Immune Response -Body responds to pathogens in different ways -responses at the cellular level are called specific defenses; different for each pathogen -responses that happen in the same way to every pathogen are called nonspecific responses; fever and inflammation (14) Nonspecific responses: -Inflammation: characterized by swelling, redness, pain, itching, and increased warmth at the infected site -happens when pathogen enters the body or when the body's tissues become damaged -basophils release chemicals called histamines in response to pathogen invasions -histamines cause the blood vessel walls to spread out, allowing fluids to come and go -WBCs head to infection site to fight off pathogens, once defeated swelling stops and tissue repair begins 5 Immune System Notes.notebook April 16, 2014 Nonspecific Response Continued: -Fever -It's a good thing! -occurs when mast cells or macrophages release chemicals causing hypothalamus to raise body temperature -body temperature returns to normal once the infection is under control -Low fevers, less than 100oF, stimulate production of interferons and increase the rate at which WBC mature (only mature cells can destroy pathogens) -this helps to increase the rate at which the body can fight infection. -High fevers are dangerous -hypothalamus loses ability to regulate body temp. -enzymes that control chemical rxns stop functioning -can cause seizures, brain damage, death 6 Immune System Notes.notebook April 16, 2014 Specific Response: -leads to acquired immunity, occurs at cellular level -body must be able to tell the difference between its own healthy cells and foreign or infected cells -Antigens: protein markers on the surfaces of cells and viruses that help immune system identify pathogens (15) -when a pathogen is detected an immune response is triggered -This sometimes involves antibodies that are made for the specific pathogen, detected by the antigen, that will bind with the pathogen or clump them together to remove them -produces an acquired immunity -body produces memory cells after fighting off the infection. -memory cells -specialized T and B cells that provide acquired immunity because they remember an antigen that's invaded the body before and will quickly attack them. (16) 7 Immune System Notes.notebook April 16, 2014 Immune system rejects foreign tissue. -all cells have protein markers on their surfaces -body must constantly decide if they are their own or foreign BUT you don't always want your body to recognize these foreign cells. -Blood transfusions or organ transplants -Tissue rejection occurs when the recipient's immune system makes antibodies against the protein markers on donor's tissue -Must determine whether the individuals are compatible before the procedure can be done -Recipients take drugs to help decrease the activity of the immune system - this makes them more susceptible to pathogens Autoimmune Disease- immune system loses the ability to recognize the body's healthy cells and attacks them (17) 8 Immune System Notes.notebook April 16, 2014 (18) Scientists have developed ways to Control Pathogens 1) Maintain a clean environment (19) 2) heat and chemicals kill pathogens outside the body -antiseptics - kill many different types of pathogens (20) -Examples: chemicals such as soap, vinegar, and rubbing alcohol 3) medicines -antibiotics - target bacteria or fungi and keep them from growing or reproducing (21) -target one type -common practice which results in antibiotic resistant bacteria 4) vaccines - substances containing the antigen of a pathogen (22) -cannot cure a person who is sick, but they work to prevent infection -allow the development of memory cells and acquired immunity against an illness without actually getting it; makes antibodies right away -you don't get sick because the pathogen is either a weakened form or dead 9