Defense Against Infectious Disease 10/31/2017 10:14 AM Defense Against Infectious Disease 6.3 © 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Preventing Pathogens From Entering Our Bodies Pathogen – any living organism or virus that is capable of causing a disease Pathogens include: Virus Bacteria Protozoa Fungi Worms

Defense Against Infection Nonspecific Infection (Prevention) Primary Defense Skin – widespread physical barrier Two primary layers: Dermis – Alive (on the bottom) Contains: sweat glands, capillaries, sensory receptors, and dermal cells that give structure and strength to skin Epidermis – mostly dead (on top) Dermal cells die and are moved up This dead layer is a good barrier against most pathogens (can’t infect a dead cell??)

Defense Against Infection Nonspecific Infection 1st Line of Defense Skin As long as skin stays intact you are protected from pathogens entering living tissues This is why it is important to cleans and cover cuts and abrasions

Defense Against Infection Nonspecific Infection 1st Line of Defense Stomach Acid Stomach secretions destroy many swallowed pathogens Acidic environment of the stomach helps to kill most ingested pathogens

Defense Against Infection 1st Line of Defense Mucus Saliva, mucus, and tears protect openings such as mouth, nose, and eyes Cells of mucus membrane secrete mucus Sticky substance that can trap pathogens This prevents pathogens from reaching cells they could infect Lysozyme - an enzyme contained in saliva mucus and tears Break down bacterial cell walls Cilia hair like structures that helps capture pathogens

Defense Against Infection Area with a mucous membrane What it is and does? Trachea The tube that carries air to and from the lungs Nasal Passages Tubes that allow air to enter the nose and then the trachea Urethra A tube that carries urine from the bladder to the outside Vagina The reproductive tract leading from the uterus to the outside

Blood Clotting Plasma proteins – have many purposes including blood clotting Cuts in the skin are sealed by blood clotting Two clotting proteins are: Prothrombin Fibrinogen Present in blood plasma Remain inactive till there is bleeding Also platelets (cell fragments) Form in bone marrow They are large cells that break up to become platelets Short life span 8-10 days

Blood Clotting Broken blood vessels: Damage cells release chemicals that stimulate platelets to adhere to the damaged area Damaged tissue and platelets release chemicals called clotting factors that convert prothrombin into thrombin Thrombin is an active enzyme that catalyzes the conversion of soluble fibrinogen into relatively insoluble fibrin Fibrin is a fibrous protein forms a mesh like network that helps stabilize the platelet plug More and more cellular debris becomes trapped in the mesh and a clot is formed.

Blood Clotting

Blood Clotting Blood clot formation in coronary arteries can cause blockage in these arteries that can lead to a heart attack

Defense Against Infection Immune Response A series of events when a pathogen enters the body Primary Immune Response – the first encounter with a pathogen Takes about a week to be successful which means you will experience symptoms of the disease Secondary Immune Response – 2nd or 3rd encounter with a pathogen Response is quicker and more intense, symptoms rarely experienced Secondary immune response to an antigen is what we know as being immune to a disease.

Defense Against Infection Antigens – any foreign substance that can stimulate an immune response Caused by proteins located on the outer surface of bacteria, viruses, or parasites

Defense Against Infection Leucocytes (AKA white blood cells) - Cells in our bloodstream that help fight off pathogens Also provide immunity for pathogens we encounter the second time

Defense Against Infection 2nd Line of Defense Macrophages - Large white blood cells (leucocyte) that are able to change their cellular shape to surround an invader Because they can change shape it is not unusual for a macrophage to encounter an invader outside the blood stream It is involved very early on in the immune process Remember this AKA

Defense Against Infection When a macrophage meets a cell it recognize whether that cell is part of the body or not. “Self” vs “not-self” Phagocytes typically contain many lysosomes in order to digest chemically whatever it engulfs This is nonspecific response because the specific pathogen has not been recognized only that it is “not-self “

Specific Defenses: The Immune Response Responds to particular pathogens Recognizing “Self” A healthy immune system recognizes all cells and proteins that belong in the body; as self Recognizing “Not-self” The immune system recognizes foreign organisms and molecules as other or “not-self”. Once recognized as “not-self” it uses cellular and chemical weapons to attack them Recognition is based on the protein molecules that make up part of the surface of all cells and viruses This is a “nonspecific” response because the ID of the pathogen has not been established just “not-self”

Specific Defenses: The Immune Response The immune system response to antigens by: Increase the number of cells that attack the invader directly Lymphocytes produce antibodies Antibodies are protein molecules that are produced by the body in response to a specific type of pathogen. Each pathogen is made up of either cells with cell membranes or viruses which have a protein coat call a capsid. The proteins are called antigens! Remember cell membranes have proteins

Specific Defenses: The Immune Response Ana antibody is a protein Each antibody is different and specific for each antigen Still very similar in structure Each antibody is a Y shaped protein Binding Site Where antibody attaches itself to an antigen Proteins

Specific Defenses: The Immune Response The leucocytes that produce antibodies are a type of cell called plasma cells We all have many different types of antibody-producing plasma cells Each type of plasma cell can produce one type of antibodies Each plasma cell produces a small number of antibodies when compared to the infection Our evolving immune system has a way of producing the same type of plasma cells when needed

Specific Defenses: The Immune Response Typical primary immune response: A specific antigen type is identified (virus) A specific plasma cell is identified that can produce an antibody that will bind to the antigen (capsid on virus) The specific plasma cell types clones itself (mitosis) to increase # rapidly The newly formed “army” of specific plasma cells produce antibodies Antibodies circulate throughout the body and find antigen Using various mechanisms the antibodies help eliminate the pathogen Some of the cloned antibody-producing plasma cells remain in the blood stream & provide immunity against a second infection (Memory Cells) Memory plasma cells of this type respond quickly if the same antigen is encountered again (second immune response)

Human Immunodeficiency Virus AIDS – Acquired Immunodeficiency Syndrome HIV – the cause of AIDS Attacks key cells within the immune system Reduces the number of active lymphocytes A loss in the ability to produce antibodies Takes many years after infection before a person lose specific immune response capability. Results in AIDS

Human Immunodeficiency Virus AIDS Infected person can no longer fight off pathogens Secondary infection often takes the life of a person Opportunistic Disease – A disease that attacks a person with weakened immune system.

Human Immunodeficiency Virus Only no-risk behavior with HIV transmission is abstinence from sexual activity and IV drug use No cure but a new variety of drugs makes it possible to survive

Human Immunodeficiency Virus Transmission – only through infected blood, semen, vaginal secretions, or breast milk Four Main ways HIV is transmitted: Sexual intercourse Sharing needles Contact with infected blood products From infected mother to her child during pregnancy, birth, or breast feeding

Antibiotics Antibiotics work because: Bacteria are prokaryotic Body cells are Eukaryotic There are differences in biochemical reaction and pathways Antibiotics take advantage of these difference

Antibiotics There are different types of bacteria: One might stop protein synthesis in bacteria Still have no effect in normal cells ability to synthesis bacteria (Affect metabolic pathways) One type may inhibit the production of a new cell wall by bacteria Cell cannot grow and divide Because viruses have no metabolism they have no effect on viruses

Antibiotics Remember that one antibiotic blocks a selective aspect of a prokaryotic cells biochemistry that is different from eukaryotes Bacteria show genetic variation just like everything else Bactria are massive in numbers and reproduce very quickly the mathematical odds that a genetic variant exists that is not affected by a antibiotic Thus in a short time surviving bacteria can reproduce rapidly

Antibiotics Long term use of antibiotics and overuse has led to many bacteria that are resistant to nearly all antibiotics (Pathogenic) in existence today Some are resistant to multiple antibiotics. Staphylococcus aureus (Staph) can be pathogenic MRSA are strains of staph that are pathogenic Difficult to treat and becoming more common

Antibiotics READ PAGE 290 Nature of Science!!!!!