Understanding Diseases Chapter 8 Lesson 1

Understanding Diseases A communicable Disease is an illness caused by pathogens that can be passed from one person to another person, animal or object. A germ is something that causes disease. A more official term for germ is PATHOGEN! A more official term for germ is PATHOGEN! They are disease causing agents which could be single or multi-cellular.

Causes and Spread of Disease Pathogens come in all different shapes and sizes: Such as: bacteria, protozoa, fungi, rickettsia, and viruses. Such as: bacteria, protozoa, fungi, rickettsia, and viruses. Not all Bacteria and Fungi are pathogens! Not all Bacteria and Fungi are pathogens! Some bacteria are beneficial and used in the digestion process. Some Fungi are used as food (mushrooms)!

Type of Pathogen DescriptionDiseases Bacteria Single celled organism that live nearly everywhere! They rapidly reproduce! Strep throat, lyme disease, urinary tract infections Viruses Smallest and simplest pathogens. They reproduce inside healthy cells. Colds, chicken pox, small pox, measles, herpes Protozoa Single celled organisms that capture other life forms for food. Live within the body as parasites. Malaria, dysentery Fungi Single celled or multi cellular organisms that feed on organic material. Yeasts and molds cause diseases. Athletes foot, ring worm, nail fungal infections. Rickettsia Pathogens similar to bacteria but multiply like viruses. Typhus, Rocky Mountain Spotted fever.

How are Pathogen’s SpreadHow are Pathogen’s Spread? How are Pathogen’s Spread Direct Contact Kissing, touching, sharing glasses or utensils, sexual activity, needle sharing. Kissing, touching, sharing glasses or utensils, sexual activity, needle sharing. Animal bites or scratches Indirect contact Doorknobs, table tops, faucet handles Doorknobs, table tops, faucet handles Insect Stings or bites Contaminated food or water Food borne illnesses, etc Food borne illnesses, etc

The Immune System Made of cells, tissues, and organs that fight off pathogens. First line of defense: Skin Skin Mucous Membranes Mucous Membranes Tears Tears Saliva Saliva Sweat Sweat Stomach Acid Stomach Acid

The Immune System Second Line of Defense Second Line of Defense A general reaction to invaders that is known as the non specific immune response. A general reaction to invaders that is known as the non specific immune response. Phagocytes play a role in this defense. White blood cells that find, engulf and digest pathogens. White blood cells that find, engulf and digest pathogens. Phagocytes release chemicals that cause inflammation at the site of an infection It causes the area to become red, swollen and warm. It causes the area to become red, swollen and warm. If the infection spreads through the whole body, the phagocytes cause a fever. If the infection spreads through the whole body, the phagocytes cause a fever.

The Immune System’s Specific Response This is the body’s third line of defense Lymph plays an important part It bathes cells and cleans them of foreign organisms. It bathes cells and cleans them of foreign organisms. Lymph nodes filter the lymph. Lymph contains lymphocytes B-Cells T-Cells Killer Cells Both recognize antigens

The Immune System’s Specific Response The Immune System’s Specific Response Antigens- substances that cause an immune reaction in the body. Once B-Cells find antigens, they begin making antibodies. Antibody- a protein in the blood that destroys a specific antigen. Antibody- a protein in the blood that destroys a specific antigen. Memory cells remember the specific antigen and they speed the production of more antibodies. T-cells and Killer Cells destroy the antigens as well.

Specific Parts of the Immune System Lymph Nodes Lymph carries captured antigens to lymph nodes where it is filtered out. Lymph carries captured antigens to lymph nodes where it is filtered out.Thymus Small gland on the upper chest that produces T-Cells Small gland on the upper chest that produces T-CellsSpleen Filters dangerous substances from the blood. Carries antigens to the spleen which prompts B-Cells to produce antibodies. Filters dangerous substances from the blood. Carries antigens to the spleen which prompts B-Cells to produce antibodies. Bone Marrow Bone Marrow produces lymphocytes Bone Marrow produces lymphocytes

Caring for your Immune System Get regular physical examinations Visit a physician when you feel ill. Follow directions on your medication. Reduce Stress Exercise Regularly. Get 8 hours of sleep each night Plan healthy meals Avoid drugs and alcohol.