GERMS are EVERYWHERE!!!!! Glo Germ Activity Who touched the doorknob when they came into the room today? Eek! You’ve come in contact with GERMS!

Diseases Bolken 2015 Pathogen – a virus, microorganism, or other organism that causes disease; an infectious agent

Types of Pathogens Bacteria: microscopic, unicellular creatures that get nutrients from their surrounding environments. Inside our bodies, they can cause infections. Virus: not considered living things because they require a host to survive such as a person or plant. They can live for short periods of time on doorknobs, desks, and toilet seats. Viruses spread from person to person making us sick. Fungi: microscopic, multicellular organisms that love damp, dark, warm places. They get nutrients by stealing it from plants or people. Protists: unicellular organisms that can spread disease through water and cause intestinal diseases.

Lytic vs. Lysogenic Cycle Life Cycle of a Virus Lytic vs. Lysogenic Cycle Have students summarize the diagram in their notes.

How are diseases transmitted? Airborne – Tuberculosis bacteria, common cold virus Foodborne – Food poisoning bacteria like salmonella Waterborne – Cholera bacteria Vector – an organisms that acts as an intermediate host that transfers a pathogen or parasite to another organism. Malaria, protist carried by mosquito Lyme Disease, bacteria carried by ticks Plague, virus carried by rats (recent NYC news) Touch/Contact – Rhinovirus (the common cold) Bloodborne – AIDS Sexual – AIDS, HPV

How can diseases be prevented? WASH YOUR HANDS!!! Have good personal hygiene Cover your mouth when you sneeze (NOT with your hands, the proper way is to use the inside of your elbow) Keep your kitchen counters clean Wash raw fruits and vegetables Wipe down cell phones, bags and purses that touch the floor, wallets, etc. Get the recommended vaccines and keep them current with boosters Be smart about sexual behaviors Education – know how to protect yourself Controlling animal vectors Wildlife officials set out meat containing rabies vaccine for wild animals to consume

Vaccines: Disease Prevention Vaccines are a highly effective way to prevent viral infections Smallpox (eradicated), measles, mumps, rubella, chicken pox, polio, tetanus, diphtheria, pertussis Vaccines are made by using dead or weakened forms of the virus to create immunity Live, or attenuated, vaccines provide the greatest protection Introduce antigens into the body to cause immunity without the risk of actual infection The body creates memory cells which can be used during a secondary immune response

How are diseases cured? Cures for most infectious diseases do not exist Instead, treatment is provided Bacterial diseases: Antibiotics Treat symptoms Viral diseases: Vaccines (prevention) Run its course

The Immune System Our immune system has three lines of defense against potential invaders: Barrier defenses Inflammatory Response Leukocytes

Defense 1: Barriers 1. Mechanical Barriers – physically block pathogens from entering the body. Skin – the single most important defense the body has. Mucous membranes – provide protection at body openings and line the respiratory, GI, urinary, and reproductive tracts. They secrete mucus, a slimy substance that traps pathogens. Cilia – hair-like structures that sweep mucus and pathogens toward body openings where they can be removed from the body. Sneezing and coughing – pathogens are removed from the nose and throat Tears – wash pathogens from the eyes. Urine – flushes pathogens out of the urinary tract.

Defense 1: Barriers 2. Chemical Barriers – destroy pathogens on the outer body surface, at body openings, and on inner body linings. Sweat, mucus, tears, and saliva all contain enzymes that kill pathogens. Urine is too acidic for many pathogens Semen contains zinc, which most pathogens cannot tolerate Stomach acid kills pathogens that enter the GI tract in food or water. 3. Biological Barriers – living organisms that help protect the body. Millions of harmless bacteria live on the human skin and in the GI tract. The harmless bacteria use up food and space so harmful bacteria cannot grow.

Defense 2: Inflammatory Response What happens when you get a cut on your hand? May become red, warm, swollen Tissue damage or infection can cause inflammatory response

Defense 3: Leukocytes Leukocytes are your white blood cells They are used in two kinds of responses Non-specific defense Specific defense

Non specific defense Same no matter what type of pathogen is involved. Phagocytosis – when a leukocyte engulfs and breaks down a pathogen and debris

Specific defense Tailored to specific pathogens Involves the lymphatic system – filters pathogens from lymph and produces lymphocytes in lymph nodes This is why your lymph nodes become swollen when you’re sick Lymphocytes – white blood cells that are activated by exposure to a particular antigen B cells – produce antibodies to a particular antigen. Memory B cells remain in the body after the immune response is over and provide immunity to pathogens bearing the antigen. T cells – destroy certain cancer cells and cells infected by viruses. Memory T cells remain in the body after the immune response and provide antigen-specific immunity to the virus. Memory B and T cells help protect the body from re-infection by pathogens that infected the body in the past.

Specific defense Immunity is the ability to resist infection by a pathogen. Active immunity results from an immune response to a pathogen and the formation of memory cells. Created through vaccinations Passive immunity results from the transfer of antibodies to a person who has not been exposed to the pathogen. Mother to child during pregnancy Mother to child by breastfeeding

What is the benefit of a fever? Moderate fevers (<103°F) are homeostatic mechanisms designed to slow the growth of pathogens that have invaded the body Fevers above this would damage essential proteins and enzymes in the body Low grade fevers are common after receiving live virus (attenuated) vaccines

Immune System Problems Autoimmune diseases occur when the immune system fails to recognize the body’s own molecules as “self,” or belonging to the person. Instead, it attacks body cells as though they were dangerous pathogens. Name of Disease Tissues Attacked by Immune System Results of Immune System Attack Rheumatoid arthritis tissues inside joints joint damage and pain Type 1 diabetes insulin-producing cells of the pancreas inability to produce insulin, high blood sugar Multiple sclerosis myelin sheaths of central nervous system neurons muscle weakness, pain, fatigue Systemic lupus erythematosus joints, heart, other organs joint and organ damage and pain

Immune System Problems An allergy is a disease in which the immune system makes an inflammatory response to a harmless antigen. Any antigen that causes an allergy is called an allergen. Allergens may be inhaled or ingested, or they may come into contact with the skin. Immunodeficiency occurs when the immune system is not working properly. As a result, it cannot fight off pathogens that a normal immune system would be able to resist. HIV is a virus that attacks cells of the immune system and eventually causes AIDS. It is the chief cause of immunodeficiency in the world today.