How Do We Get Sick? Almost everyone gets sick. Diseases are any changes, other than injuries, that disrupt the normal functions of the body. Diseases can be inherited, caused by materials in the environment, or produced by disease-causing organisms. These organisms are called pathogens. Diseases caused by pathogens are generally infectious because the pathogens usually infect, or enter, the body of the person that gets sick. 1. On a sheet of paper, make a list of some of the infectious diseases you have had. 2. Choose one of the diseases on your list. How did you feel when you were sick with this disease? How was the disease treated? 3. How did you get the disease described in question 2? What do you think caused this disease?

Pathogens and Disease Review Pathogen Types Disease Agent That Causes Disease Method of Transmission Common cold Rhinovirus Two types (A, B), plus subtypes Varicella Paramyxovirus Mycobacterium tuberculosis Neisseria meningitidis Vibrio cholerae Clostridium tetani Trypanosoma Plasmodium Entamoeba histolytica Schistosoma Taenia saginata Imperfect fungi Airborne; direct contact with infected person Airborne; droplet infection; direct contact with infected person Droplets in air; direct contact with secretions of infected person Droplets in air; contaminated milk and dairy products Direct contact with a carrier Contaminated drinking water Contaminated wound; usually puncture wound Spread by tsetse fly Spread by Anopheles mosquitoes Freshwater streams and rice paddies Contaminated meat Contact with infected person Exchange of hats, combs, or athletic head gear with infected person Viruses Influenza Chickenpox Measles Bacteria Tuberculosis Meningitis Cholera Tetanus Protists African sleeping sickness Malaria Amoebic dysentery Worms Schistosomiasis Beef tapeworm Fungi Athlete’s foot Ringworm

Do Now: 1. Turn in Lab report to bin Do Now: 1. Turn in Lab report to bin. Make sure to have green rubric attached with your name on it. 2. List one illness you have had in the past year. - Describe the symptoms. - Describe the treatment. - Describe how this illness is transmitted. 3. Write down what how you think the immune system protects us from pathogens.

IMMUNITY Immunity: Pathogen: ability of the body to resist a specific pathogen Pathogen: disease causing agent or organism

IMMUNITY There are three “lines of defense” within your body that serve to keep you healthy………

Two types of defense mechanisms Non-specific – prevent pathogens from entering the body Specific – Destroy harmful pathogens that enter the body Draw a picture of body with bacteria outside. Draw a picture of body with bacteria inside.

“Keep pathogens out of the body tissues - Non-specific defense” 1st Line of Defense “Keep pathogens out of the body tissues - Non-specific defense” Skin (most important) Tears Hair Mucus membranes Saliva Stomach acid Earwax Lysozyme: is an enzyme which breaks down the cell walls of bacteria; present in body secretions

Destroy them non-specifically with an inflammatory response” 2nd Line of Defense “Pathogens have invaded body. Destroy them non-specifically with an inflammatory response” Example: If pathogens enter the body, histamines are released which allow phagocytic (pathogen eating) white blood cells move into the area to destroy the bacteria Histamine: chemical that tells white blood cells to move to area of infection Symptoms swelling, warmth redness, pain pus Antihistamines: drugs that stop the histamine response Allergic response is too much histamine being produced Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.

The Inflammatory Response Briefly describe the diagram below. Wound Skin Phagocytes move into the area Bacteria enter the wound Capillary

So an increase in WBC’s means….

2nd Line of Defense Continued… A FEVER IS A GOOD THING………. The immune system also releases a chemical that increases your body temperature which can kill the pathogens The fever also increases heart rate so white blood cells can get to the infection site faster. Discuss homeostasis, a fever is outside the optimal range for pathogens to comfortably live and multiply

3rd Line of Defense - The Immune Response - “The 2nd line of defense has failed. Resort to killing the pathogens specifically with chemical warfare.” White blood cells release “antibodies” to attach to “antigens” on the pathogens and destroy them. White blood (B-Cells) cells “remember” how to make those antibodies for the future. antibody What is the different between non-specific and specific – clarify during this slide

3rd Line of Defense - The Immune Response - “The 2nd line of defense has failed. Resort to killing the pathogens specifically with chemical warfare.” White blood cells release “antibodies” to attach to “antigens” on the pathogens and destroy them. White blood (B-Cells) cells “remember” how to make those antibodies for the future. What is the different between non-specific and specific – clarify during this slide

Antigen- binding sites How Does the White Blood Cell Know What to Attack? Each pathogen has a different shape antigen (surface protein) and only specific antibodies will bind with it and destroy the pathogen. Antigen- binding sites Antigen Antibody How can we compare antibodies and antigens to a lock and key model?

There are three “lines of defense” within your body that serve to keep you healthy……… 1st Line of Defense 2nd Line of Defense 3rd Line of Defense

Why is it that people tend to get illnesses like Hand-Foot & Mouth Disease once, and then never again? Primary immune response Occurs when a specific pathogen enters your body for the first time It takes several days for WBC’s (T-cells) to figure out how to make the antibodies to destroy it In the meantime, you get sick

Why is it that people tend to get illnesses like Hand-Foot & Mouth Disease once, and then never again? Secondary Immune Response Occurs when that same pathogen enters your body again WBC’s, called Memory B-cells, remember that pathogen and how to make the antibody. They do so QUICKLY, before it has the chance to make you sick

What are Antibodies and Antigens What are Antibodies and Antigens? What do they have to do with your immune response when your body is exposed to a familiar pathogen?

SLOW antibody production pathogen has opportunity to reproduce YOU GET SICK FAST antibody production pathogen has no opportunity to reproduce YOU DON’T GET SICK Might not do active and passive immunity – only if you have time

Made possible by memory cells. -- permanent immunity -- Active Immunity Occurs when your own white blood cells (B-cells) learn and remember how to make the necessary antibodies that kill a pathogen, keeping you immune for your whole life. Made possible by memory cells. -- permanent immunity -- Examples: having hand, foot & mouth disease once, then never again immunity after a vaccination a vaccine is a weakened form of a pathogen which causes your body to make antibodies to it

Passive Immunity -- temporary immunity -- Occurs when you receive the antibodies of immunity from somebody else -- temporary immunity -- Examples: being immune to a pathogen for a few months after receiving a blood transfusion fetus developing inside its mother baby for 6 months after birth breastfeeding baby

Briefly describe the difference between active immunity and passive immunity?