Transcript File
Chapter 10 Bacteria and Viruses Section 10C-2 Defense against infectious disease A. Structural defense – “First line of defense” keep pathogens out! 1. Skin and mucous membranes lining respiratory, digestive and urinary tracts 2. Mucus traps microbes and disposes of them 3. Stomach acid kills swallowed pathogens 4. Intestinal flora (good bacteria living in intestines) competes against bad bacteria 5. Tear glands make lysozyme, which kills bacteria entering eyes Section 10C-2 Defense against infectious disease B. Nonspecific defenses - “Second line of defense” Inflammatory response, phagocytic cells, lymphatic system, fever – – Inflammation – increases blood flow in response to chemicals released by infected cells Phagocytic cells – white blood cells arrive due to increased blood flow, recognize invaders, form a barrier Pus: fluid, WBC and dead pathogens Section 10C-2 Defense against infectious disease B. Nonspecific defenses (cont.) – – Lymphatic system – helps clean body of pathogens and toxins, phagocytizes pathogens Fever – Raised body temperature, makes environment less favorable for many pathogens & accelerates reactions that activate defenses (if fever is too high, may cause damage to body tissues) Section 10C-2 Defense against infectious disease C. Specific defenses – “Third line of defense” – immune system (Ch. 22) – Antibodies – proteins made by specific cells in the blood that combat specific pathogens or their toxins – Other special cells with particular duties have “chemical memory” of pathogen Section 10C-2 Defense against infectious disease D. Medical control- “chemical warfare” – – Chemotherapy – use of chemical agents to treat or prevent disease. Meant to injure the pathogen without harming host’s body but may have side effects. Antibiotics: Chemicals produced by living things Work by interfering with enzymes and metabolic pathways that bacteria have (& humans don’t have), like cell wall synthesis Are nonspecific (kill many kinds of bacteria), but don’t kill virus Types: Bactericidal- kill bacteria, Bacteriostatic- inhibit growth of bacteria Example: Penicillin – The first antibiotic, a mold, discovered by Sir Alexander Flemming, 10C-3 Disorders: diseases not caused by a pathogen 1. Inherited disorders – due to a gene or inherited 2. 3. 4. 5. tendency (ex. diabeties) Injuries – broken bone, burns, etc. Deficiency disease – lack of a vitamin/mineral Chemical poisoning or radiation sickness – due to exposure to environmental factors Other organic disorders like stroke, kidney stones, etc. caused by unknown or partially understood causes 10C-3 Disorders (cont.) • Benign tumors – abnormal growth of cells • Biopsy – take tissue sample • Pathologist – tissue specialist, analyzes tissue from biopsy to determine benign or malignant (benign tumors usually surgically removed) • Cancer – malignant tumor (rapid cell growth) • May metastasize (separate from parent tumor and spread to other parts of the body) 10C-3 Disorders (cont.) • Cancer 1. Initiation: 1st step to developing cancer, cells become partially cancerous, happens in 1 of 3 ways A. Carcinogenic chemicals – cause cancer (ex. tobacco products) B. Radiation – ultraviolet or x-rays can cause (ex. skin cancer) C. Viruses – some viruses linked to some cancers (ex. HPV cervical cancer) 10C-3 Disorders (cont.) • Cancer 2. Promotion: once cell has become potentially cancerous, diet/general health/genetic makeup help promote conversion of initiated cells to cancer cells (tumor forms) – see p. 292 for steps to reduce cancer risk 10C-3 Disorders (cont.) • Cancer Treatments 1. Surgery – leading method, remove cancer cells 2. Radiation – x-rays or radioactive isotope emission to destroy cancer cells, side effects harsh, can cause new tumors 3. Chemotherapy – chemicals aimed at destroying cancer cells, side effects harm other cells in the body Facet: clinical death – absence of brain waves for 24-48 hours