AP Biology “Fighting the Enemy Within” Immune System lymphocytes attacking cancer cell phagocytic leukocyte lymph system

Regents Biology Avenues of attack  Points of entry  digestive system – mouth – saliva/acid  respiratory system – nose – hairs/mucus  urinary system – urethra (shorter in females)  genitals  break in skin – cut  eyes  Pathways for attack  circulatory system  lymph system How pathogens move around your body

Regents Biology Why do we need an immune system?  Attack from the outside & inside  cells are packages of proteins, carbohydrates & fats  no cell wall – plasma membrane – semi permeable  organisms must defend themselves against (pathogens) invaders  viruses – NOT LIVING  HIV, flu, cold, measles, chicken pox, SARS  bacteria  pneumonia, meningitis, tuberculosis, strep throat  fungi  yeast, ringworm, athlete’s foot  protists  amoeba (disentary), Lyme disease, malaria  cancer cells – come from within  abnormal body cells – “starve” healthy cells

Regents Biology How are invaders recognized?  Antigens  chemical name tags on the surface of every cell – Protein  “self” vs. “invader” – ALL BASED ON SHAPE disease-causing bacteria disease-causing virus one of your own cells antigens say: “I belong here” antigens say: “I am an invader”

Regents Biology 1st line: Physical Barriers  non-specific defense  external barriers  skin & mucus membranes  excretions  sweat  stomach acid  tears  mucus  saliva  “lick your wounds” Lining of trachea: ciliated cells & mucus secreting cells

Regents Biology 2nd: Generalist, broad range patrols  White blood cells  attack invaders that get through the skin  recognize invader by reading antigen  surface name tag – BASED ON SHAPE  phagocyte cells  macrophages  “big eaters”  “eat” like amebas  engulf (endocytosis, then fuse with lysosome, and finally exocytosis) Macrophage “eating” bacteria

Regents Biology histamines  increases blood flow (red and warm)  brings more white blood cells to fight bacteria (pus)  brings more red blood cells & clotting factors to repair Why do injuries swell?  Inflammation - injured cells release chemical signals

Regents Biology Fever  When a local response is not enough  full body response to infection  raises body temperature – 37 C or 98.6 F  TOO high – dangerous – remember enzymes????  higher temperature helps in defense  slows growth and metabolism of pathogens  helps macrophages  speeds up repair of tissues

Regents Biology 3rd line: Lymphocytes  Specific defense  responds to specific invaders  recognizes specific foreign antigens  white blood cells  B cells & antibodies  T cells B cell

Regents Biology B cells & antibodies ACTIVE IMMUNITY  B cells  white blood cells that attack invaders in blood  mature in Bone marrow  Patrolling B cells  make antibodies against invader immediately  Memory B cells  remembers invader  can make antibodies quickly the next time  protects you from getting disease more than once

Regents Biology  Proteins made by B cells that tag invaders in the blood so macrophages can eat them  tag says “this is an invader”  gotcha!  biological “handcuffs”  antibody attaches to antigen of invader – they “FIT” Antibodies macrophage eating tagged invaders invading germs tagged with antibodies Y Y Y Y Y Y Y B cells releasing antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y Y

Regents Biology B cells immune response invader (foreign antigen) Y Y Y Y B cells Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y “reserves” memory B cells Y Y Y Y Y Y Y Y Y Y Y Y Y B cells release antibodies patrol blood forever recognition 10 to 17 days Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Antibody “fits” with antigen

Regents Biology Vaccinations  Exposure to harmless version (“dead”, weakened, or part) of a pathogen (“germ”)  stimulates immune system to produce antibodies to invader - ACTIVE IMMUNITY  rapid response if future exposure  Most successful against viral diseases  Ex: flu, chicken pox, HPV, MMR, swine flu, whooping cough, polio, small pox Jonas Salk  Developed first vaccine  against polio

Regents Biology  Vaccinations – Active Immunity  advantage  don’t get illness  long term immunity - produce antibodies for life  works against many viruses & bacteria  disadvantage  not possible against all invaders  Breastfeeding - Passive Immunity  mother’s milk gives baby antibodies & keeps baby healthy Protecting you from disease

Regents Biology Curing you of disease  Antibiotics = medicine  advantage  kill bacteria that have successfully invaded you  make you well after being sick  disadvantage  use only after sick  only good against bacteria  possible development of resistance by bacteria (if don’t use correctly) – ALWAYS TAKE THE ENTIRE Rx  can get sick again

Regents Biology Diseases of the immune system  HIV: Human Immunodeficiency Virus  infects helper T cells  helper T cells can’t activate rest of immune system  body doesn’t hear the alarm  AIDS: Acquired ImmunoDeficiency Syndrome  immune system is weakened  infections by other diseases  death from other invading diseases or cancer

Regents Biology Immune system malfunctions  Auto-immune diseases  immune system attacks own cells  lupus  antibodies attack many different body cells  rheumatoid arthritis  antibodies causing damage to cartilage & bone  diabetes  insulin-making cells of pancreas attacked & destroyed  multiple sclerosis  T cells attack myelin sheath of brain & spinal cord nerves  fatal

Regents Biology Immune system malfunctions  Allergies  produce histamines  over-reaction to harmless antigens  allergens  proteins on pollen  proteins from dust mites  proteins in animal saliva  body mistakenly thinks they are harmful attackers (antigens)