Chapter 35: Immune System & Disease

Chapter 35: Immune System & DiseaseMs. LuacesHonors BiologyPathogens

35.1 Infectious DiseasePasteur & Koch came up with the germ theory of disease: infectious diseases occur when microorganisms cause physiological changes that disrupt normal body functionCan be caused by viruses, bacteria, fungi, protists and parasitesExcept for parasites, all others known as pathogens

35.1 Infectious DiseaseKochs Postulates:1. Pathogen must always be found in sick body but not healthy body2. Pathogen can be isolated & grown in lab3. If pathogen infects healthy host, should produce sickness4. Pathogen can be isolated from new host & looks identical

35.1 Infectious DiseaseWhats the different between a symbiont and pathogen?Symbionts are either harmless or beneficialPathogens destroy host cells, release poisons, block blood flow, and take up hosts nutrients

35.1 Infectious DiseaseDiseases spread through coughing, sneezing, physical contact, exchange of body fluids, contaminated water/food/animals

35.1 Infectious DiseaseNatural selection favors pathogens with adaptations that help them spread from host to hostCoughing, sneezing, body-to-body contact, sexual activity, drug usage, poor sanitationBest way to avoid infection is to constantly wash your hands!

35.1 Infectious DiseaseThose pathogens that thrive in both human and animal hosts are known as zoonosisWest Nile virus, Mad cow disease, Lyme disease, EbolaCarriers of the disease who dont get sick are known as vectors

Lets Practice!Pg. 475 476Q & AWork with a buddy one sheet of paper for both of you!

35.2Nonspecific DefensesInclude skin, tears and other secretions, inflammatory response, interferon's and feverFirst line of defense: skin, which is the most widespread defense

35.2Nonspecific DefensesPathogens can enter through the mouth, nose or eyes which are protected by saliva, mucus and tearsContains lysozyme which breaks down bacterial cell wallsStomach secretions (acid) also protect

35.2Nonspecific DefensesSecond line of defense includes inflammatory response, interferon's, and fever

35.2Nonspecific DefensesInflammatory response causes areas to become red and painful because of histamines (release by mast cells to increase flow of blood and fluids to the area)White blood cells (phagocytes) will then engulf and destroy bacteria

35.2Nonspecific DefensesInterferon's inhibit synthesis of viral proteinsAka interfere with viral growth, slowing down the production of new viruses

35.2Nonspecific DefensesFever increases body temperature to slow down or stop the growth of some pathogensSometimes also speeds up several parts of the immune response

35.2 Specific DefensesSpecific defenses distinguish between self and other and inactivate / kill any foreign substance or cell that enters the bodyNonspecific = general threat Specific = particular pathogen

35.2 Specific DefensesRecognizes specific chemical markers on own cells own secret passwordIf the marker is not recognized, will attack and remember it for later as non-self so that it can kill it quickly if it enters the body again: immune response

35.2 Specific DefensesAntigens are any foreign substances that can stimulate an immune responseFound on the outer surface (the flag)Immune responds by increasing # of cells to attack or produce proteins called antibodies

35.2 Specific DefensesAntibodies tag antigens for destruction by immune cells (the alert!!)The shape of each antibody allows it to bind to only one antigen very specific

35.2 Specific DefensesMain working cells of the immune system are B lymphocyte cells: grow and mature in red bone marrow; have antibodies on them; attack in body fluidsT lymphocyte cells: grow in red bone marrow but mature in thymus; have to be presented with antigen to attack