Ch. 26 Communicable or Infectious Diseases

Lesson 1 Vocabulary Communicable disease – Disease caused by direct or indirect spread of pathogens from one person another. Pathogens- tiny microorganisms that cause disease by infecting or invading the cells and tissues of the body. Bacteria – one-celled microorganisms that is the most widespread of living things. Not all bacteria cause disease, but a lot do. Saprophytes- bacteria that digest non-living food materials, such as meat or milk.

PARASITES- bacteria that feed on a living plant or animal HOST- the plant or animal the bacteria feeds from. RESIDENT BACTERIA- bacteria that live in your mouth, intestines and skin and help protect you from harmful bacteria. A single bacterial cell divides every 20-30 min. COMPETITION- Kills many of them to keep them under control TOXINS – bacteria that produces poisons. Ex. Botulism, tetanus Bacterial diseases include: pneumonia, food poisoning, tetanus, tuberculosis, strep throat, syphilis and gonorrhea.

VIRUSES – small, simple life-like forms, smaller than bacteria VIRUSES – small, simple life-like forms, smaller than bacteria. No nucleus, no cytoplasm and no cell membrane. All are parasites. CELL SPECIFIC - They attack only specific cells Rabies- only brain cells Polio-nervous system Cold- respiratory system Hepatitis – liver Mumps and mononucleosis- lymph glands Small pox, chicken pox- skin tissues

OTHER PATHOGENS Rickettsias- between a bacterium and virus. Grow in intestinal tracts of insects. Insects carries disease to humans- such as lice, mites and ticks. Cause Rocky Mountain spotted fever and Typhus fever. Fungi- simple organisms that cannot make their own food. They are saphrophytes Yeast and mushrooms Diseases caused by fungi-athletes’s foot, ringworm, toe fungus.

Parasites PROTOZOANS- Single-celled organisms-larger than bacteria Disease producing ones typical in tropical areas Cause- malaria, African sleeping sickness and amoebic dysentery FLATWORMS and ROUNDWORMS Flukes- invade blood, intestines, liver, or lungs. Tapeworms- intestines Roundworms- intestines, muscles Trichinosis-eating infected pork that is not well-done.

Body Defense Mechanisms Disease spreads in many ways: Indirect contact- airborne droplets,touching objects an infected person has touched, using a needle an infected person has touched. Direct Contact- physical contact such as kissing, sexual contact, blood to blood contact Contact with animals- mosquito bites, animal bites and scratches-rabies, malaria African sleeping sickness

IMMUNE SYSTEM I .Nonspecific Resistance-defense acts the same way each time it is invaded Mechanical mechanisms- formation of barriers to keep pathogens out- skin, mucous membranes in your mouth, nose, bronchial tubes, cilia,tears and saliva. Chemical Barriers- acidic digestive juices, chemicals in tears, saliva and sweat. Other chemicals in cells Cells- White blood cells called phagocytes group together to destroy foreign substances- Phagocytosis- the process by which the phagocytes destroy pathogens. Neutrophils- most active phagocyte Inflammatory Response- increased blood flow to area to bring phagocytes- redness and swelling occur

II. Specific Resistance- A. specific protection against specific types of pathogens B. Keeps a record of the pathogens in case they attack again. C. Lymphocyte- type of white blood cell that fights pathogens- travels through the lymphatic system and circulatory system Lymphocytes multiply in the spleen, tonsils and lymph nodes. T cells and B cells kill pathogens and make antibodies. B cells are stimulated by T cells to make antibodies. 3. Antibodies- proteins that destroys or neutralize pathogens. They remain in your blood to fight the pathogen should it return.

Prevention Avoid contact with pathogens Bathe or shower everyday Store and prepare food safely Wash your hands after using the restroom, sneezing, changing diapers or preparing food Cover your mouth when sneezing or coughing Get medical treatment- do not bring your sickness to school or work Avoid contact with sick people

IMMUNITY Immunity- the bodies natural resistance to many pathogens Active Immunity- the immunity your body develops to protect you from disease – once you have chicken pox your antibodies will protect you from further infection from that disease. Vaccines- preparations of dead or weakened viruses that provide active immunity to some pathogens-smallpox, polio, measles, etc. Vaccination- a process by which vaccine is injected into the body. Passive Immunity- the immunity a mother passes on to her baby for the first few months of life. The baby will develop antibodies to the same diseases as the mother.

Vaccines Live-Virus – Weakened virus strong enough to produce antibodies, but not the disease-measles, rubella and oral polio vaccines included Killed-Virus – not as powerful as live-virus requires booster shots - hepatitis B Toxoids – bacterial diseases like diphtheria and tetanus-chemically treated bacteria toxins establish active immunity- boosters needed Immunization is required to enter schools in the U.S.