Infectious Diseases What causes them, and How do we stay healthy?

Standard 10: 10A -- Students know the role of the skin in providing nonspecific defenses against infection 10A -- Students know the role of the skin in providing nonspecific defenses against infection 10B -- Students know the role of antibodies in the body’s response to infection 10B -- Students know the role of antibodies in the body’s response to infection 10C -- Students know how vaccination protects an individual from infectious diseases 10C -- Students know how vaccination protects an individual from infectious diseases Organisms have a variety of mechanisms to combat disease.

10D -- Know the important differences between bacteria and viruses (i.e.: their requirement for growth and replication, the body’s primary defenses against bacterial and viral infections, and effective treatments of these infections) 10D -- Know the important differences between bacteria and viruses (i.e.: their requirement for growth and replication, the body’s primary defenses against bacterial and viral infections, and effective treatments of these infections) 10E -- Know why an individual with a compromised immune system (ex: a person with AIDS) may be unable to fight off and survive infections by microorganisms that are usually benign 10E -- Know why an individual with a compromised immune system (ex: a person with AIDS) may be unable to fight off and survive infections by microorganisms that are usually benign

10F -- Students know the roles of phagocytes, B-lymphocytes, and T-lymphocytes in the immune system 10F -- Students know the roles of phagocytes, B-lymphocytes, and T-lymphocytes in the immune system

What is a Virus? Nonliving particles that have a nucleic acid core and a protein-containing capsid. Nonliving particles that have a nucleic acid core and a protein-containing capsid. Cause disease by disrupting the body’s homeostasis (balance).Cause disease by disrupting the body’s homeostasis (balance). Don’t exhibit all life criteria:Don’t exhibit all life criteria: Don’t carry out respiration No growth or development (all they can do is replicate) Host Cell – where a virus replicates Host Cell – where a virus replicates Cannot be killed by antibiotics (medicines)Cannot be killed by antibiotics (medicines)

Viral Structure:

T4 Virus – E. Coli

HERPESHIV

Influenza – The common Cold

Viral Replication – Lytic Cycle 1.Attachment – attaches to host cell 2.Entry – injects nucleic acid into host cell 3.Replication – host uses it energy to replicate viral nucleic acid 4.Assembly – New viruses made (in 30 minutes, 200 new viruses) 5.Lysis and Release – Host cell breaks open, and virus particles are released

What is Bacteria? Small cell with all the structures necessary to carry out its life functions.Small cell with all the structures necessary to carry out its life functions. 2 types of Bacteria:2 types of Bacteria: 1.Archaebacteria – inhabit extreme environments 2.Eubacteria – live almost everywhere else. (heterotrophs, photosynthetic autotrophs, and Chemosynthetic autotrophs)

Structure of Bacteria Prokaryotic Cells (typically) Prokaryotic Cells (typically) Contain:Contain: Chromosomes – Single DNA molecule (no nucleus) Cell Wall – shape and support Plasma Membrane – regulates entry and exit Pilus – help stick to a surface and bridge for DNA exchange Flagellum – Whip-like tail for locomotion Ribosomes – helps in protein formation

Bacterial Reproduction Asexual Asexual Binary Fission – 1.Chromosome replicates, attaches to plasma membrane 2.Cell grows and splits Sexual Reproduction Sexual Reproduction Conjugation – Transfers all or part of chromosomes to another bacteria through its pilus

How do bacteria make you sick? Produce disease in one of 2 ways:Produce disease in one of 2 ways: 1.Damage cells and tissues of the infected organism directly, by breaking down the cells for food. 2.Release toxins (poisons) that travel throughout the body interfering with homeostasis of the host.

Defense Against Infectious Diseases How do we stay healthy?

What is an Infectious Disease? Disease = a change that disrupts the homeostasis in the body Disease = a change that disrupts the homeostasis in the body Pathogens = disease causing agents (what makes you sick) Pathogens = disease causing agents (what makes you sick)

Our Bodies Defense Mechanisms: Skin – the first line of defense Skin – the first line of defense Phagocytes, B-lymphocytes, and T- lymphocytes – the 2 nd line of defense Phagocytes, B-lymphocytes, and T- lymphocytes – the 2 nd line of defense Antibiotics and Vaccines – outside sources of help Antibiotics and Vaccines – outside sources of help

What is the role of Phagocytes? Phagocytes – White blood cells that surround and destroy pathogens. Phagocytes – White blood cells that surround and destroy pathogens. Macrophages – Macrophages – Located in body’s tissues Giant Scavengers – engulf pathogens and damaged cells

What if phagocytes don’t help? Acquired Immunity – defense against a specific pathogen by building up resistance Acquired Immunity – defense against a specific pathogen by building up resistance Lymphatic System – the body’s system that is in charge of keeping it healthyLymphatic System – the body’s system that is in charge of keeping it healthy Uses T-lymphocytes (T-cells) and B- lymphocytes (B-cells)Uses T-lymphocytes (T-cells) and B- lymphocytes (B-cells)

What are T and B cells all about? Produced in bone marrow Helper T-cell – activates B-cells Helper T-cell – activates B-cells Cytotoxic T-cell – “killer T-cells” produce clones to enter infection site, release enzymes into pathogens which causes them to lyse (explode) and die. Cytotoxic T-cell – “killer T-cells” produce clones to enter infection site, release enzymes into pathogens which causes them to lyse (explode) and die. B-cells – turn into antibodies once activated by T-cells B-cells – turn into antibodies once activated by T-cells Memory B-cells – remain in blood stream armed and ready for a 2 nd attack Memory B-cells – remain in blood stream armed and ready for a 2 nd attack

What are antibodies? Antibodies – proteins produced to react with and disable antigens Antibodies – proteins produced to react with and disable antigens Antigens – Foreign substances that stimulate an immune response in the body Antigens – Foreign substances that stimulate an immune response in the body Antigens are displayed on pathogen like an address ( mark pathogens ), Antibodies attach to antigens to help the body fight the intruder.

What about Antibiotics? Substance produced by a microorganism that kills or inhibits the growth of other microorganismsSubstance produced by a microorganism that kills or inhibits the growth of other microorganisms Use to fight and kill bacteriaUse to fight and kill bacteria Does NOT work with virusesDoes NOT work with viruses Why do you think that is?

How can Vaccinations help? Vaccine = substance with weakened, dead, or incomplete portions of pathogen (typically a viral pathogen) Vaccine = substance with weakened, dead, or incomplete portions of pathogen (typically a viral pathogen) Produces an immune responseProduces an immune response Creates antibodies in the body (T and B cells)Creates antibodies in the body (T and B cells)

What are Retroviruses Contain RNA instead of DNAContain RNA instead of DNA When cell is infected, it produces DNA copy of RNA to insert into the Host Cell’s DNAWhen cell is infected, it produces DNA copy of RNA to insert into the Host Cell’s DNA Lays dormant for long time (hidden from bodies defenses)Lays dormant for long time (hidden from bodies defenses) HIV is a retrovirusHIV is a retrovirus Harder to stop because can undergo more mutations.Harder to stop because can undergo more mutations.

What is HIV and AIDS all about? Caused by HIV (Human Immunodeficiency Virus)Caused by HIV (Human Immunodeficiency Virus) Compromises your immune systemCompromises your immune system Kills white blood cells (Helpers T-Cells) and can lead to AIDS (Acquired Immune Deficiency Syndrome)Kills white blood cells (Helpers T-Cells) and can lead to AIDS (Acquired Immune Deficiency Syndrome) HIV contains 2 copies of RNA that penetrate a cell and hide for months. In the infected cell, RNA is used to synthesize viral DNA.HIV contains 2 copies of RNA that penetrate a cell and hide for months. In the infected cell, RNA is used to synthesize viral DNA.