INFECTIONS&

VACCINATIONSWK: 04/17—04/20

On Tuesday You Learned:

• 10b/10d: The role of antibodies and how they respond to infections

• **Let’s Review!• -What is the area filled with protein called on a virus?

Where does it attach?• -What are the two types of viral infections we learned

about?• -What is a prophage?• -What is a retrovirus?

Today You Will Learn:

• 10c: Understand how vaccination protects individuals from infectious diseases

• (Intro to 10d): Important differences between bacteria and viruses—about the body’s primary defenses against bacteria and viral infections, and treatments

What Is A Disease?

• A disease is any change, other than an injury, that disrupts the normal functions of the body

• Some are produced by agents, such as bacteria, viruses, and fungi

• Others are caused by materials in the environment, such as cigarette smoke

• Few others are inherited, like hemophilia• Diseases caused by PATHOGENS are generally called

infectious diseases

Source: Levine/Miller 40-1

BECAUSE SOME OF YOU ASKED…

• How is a disease spread?– From one person to another

through coughing, sneezing, or physical contact

– Pathogens in the air—when one sneezes

– Through contaminated water or food

– Through contaminated animals—animals that carry a pathogen from one person to another are called vectors

Source: Levine/Miller 40-1

Fighting Infections

• ANTIBIOTICS are infection-fighting drugs—they are compounds that kill bacteria without harming the cells of the human or animal hosts—they work by interfering with the cellular processes of microorganisms

• Source: Levine/Miller 40-1

HOW DOES BACTERIA CAUSE DISEASE?

• Bacteria lives on and within our bodies—NOT ALL BACTERIA IS BAD. In fact, some is helpful to our essential functions, like digesting food

• The role of pathogenic bacteria, on the other hand disrupts the body’s equilibrium by interfering with its normal activities and producing disease

• HOW? – By breaking the cells for food; destroys tissue– Or, by releasing toxins through the blood stream that interfere with

the activity of the host cell

Source: Levine/Miller 19-3

How to Prevent/Kill Bacteria

• Sterilization: killing bacteria with heat (homeostatic ex: fever)

• Disinfectants: chemical solutions that kill pathogenic bacteria. WARNING: constant use of disinfectants will cause bacteria to become “immune” to it, meaning they would no longer be as effective

• Food Processing: refrigerating food—temperature takes bacteria longer to multiply

Source: Miller/Levin 19-3

The Immune System

• Remember that the function of the IMMUNE SYSTEM is to fight infection through the production of cells that inactivate “foreign substances” (pathogens) or cells—immunity

TWO KINDS=1. Non-specific defenses guard against infections by

keeping most things out of the body2. Specific defenses track down harmful pathogens

that manage to get through the non- specific defenses

Source: Miller/Levin 19-3

How Does The Body Defend Against Infections?

• (Non-Specific) First Line Defense: The skin!• (Non-Specific) Second Line Defense: Inflammatory

response—react to tissue that the infection has damaged by inflaming

• WHITE BLOOD CELLS!!! (remember WBC protect against infection?) White Blood Cells (Phagocytes) fight bacteria, but as a result inflames the tissue

• Interferons interfere with the growth of the virus so that they don’t affect cells as easily

Source: Miller/Levin 40-2

How the Body Protects Itself Against Infections

• (SPECIFIC DEFENCES) When the pathogen gets through the non-specific guards, the specific defenses kick in to fight the virus—antigens (T cells and B cells) trigger this response!

• Memory B cells remember the antibody necessary to kill off that particular pathogen, making it less likely that the disease will form again

• CELL MEDIATED IMMUNITY: when a virus or other pathogen goes into a living cell and antibodies alone cannot destroy virus—This is when Killer T cells are necessary to kill off infection

VACCINATIONS

• A vaccine is a preparation of weakened or killed pathogens. It prompts the body to produce immunity to the disease—in other words, train the body to kill off those pathogens

• Vaccines are used to fight VIRUSES because antibiotics can’t kill a virus in the same way that it kills bacteria

Source: Miller/Levine 19-3

ACTIVE IMMUNITY

• More than 20 serious human diseases can be prevented by vaccination

• How do Vaccines work? They stimulate the immune system to create millions of plasma cells ready to produce antibodies—when a body is “trained” for a specific disease, we call that ACTIVE IMMUNITY