The Immune System and Disease

The Immune System and Disease

It’s you against the world…It’s you against the world…

What is a disease?What is a disease? A disease is any change,

other than an injury, that disrupts the normal functions of the body.

Some diseases are caused by pathogens, or “sickness-makers”. These are generally called infectious diseases. Pathogens can be

bacteria, viruses, materials in the environment, etc.

Other diseases can be hereditary.

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

Some diseases are caused by pathogens, or “sickness-makers”. These are generally called infectious diseases. Pathogens can be

bacteria, viruses, materials in the environment, etc.

Other diseases can be hereditary.

The Germ Theory of Disease

The Germ Theory of Disease The idea that infectious diseases are

caused by microorganisms of different types, or germs.

The idea that infectious diseases are caused by microorganisms of different types, or germs.

Koch’s PostulatesKoch’s Postulates

Pathogen should always be found in a sick individual

Must be able to isolate pathogen and grow in culture in lab.

When placed in new hosts, pathogen should cause same disease as original individual

When isolated from second host, pathogen should be identical to original pathogen.

Pathogen should always be found in a sick individual

Must be able to isolate pathogen and grow in culture in lab.

When placed in new hosts, pathogen should cause same disease as original individual

When isolated from second host, pathogen should be identical to original pathogen.

Agents of DiseaseAgents of Disease

For many pathogens, the human body is the perfect environment for growth - warm, dark and moist with an abundance of nutrients

For many pathogens, the human body is the perfect environment for growth - warm, dark and moist with an abundance of nutrients

VirusesViruses Tiny particles

that invade and replicate in cells

Can infect nearly every type of organism

Tiny particles that invade and replicate in cells

Can infect nearly every type of organism

Bacteria Bacteria

Cause disease by either breaking down tissue for food or releasing toxins that harm the body

Cause disease by either breaking down tissue for food or releasing toxins that harm the body

Protists Protists Unicellular eukaryotes that usually exist

independently or in colonies and are not usually associated with disease

Plasmodium - a protist that causes malaria Trypanosoma - causes African sleeping sickness

Unicellular eukaryotes that usually exist independently or in colonies and are not usually associated with disease

Plasmodium - a protist that causes malaria Trypanosoma - causes African sleeping sickness

Worms Worms Flatworms and roundworms are

responsible for many human diseases Schistosoma Tapeworms Hookworms

Flatworms and roundworms are responsible for many human diseases Schistosoma Tapeworms Hookworms

Fungi Fungi

Most are harmless - mushrooms Some cause serious problems Tinea pedis - athlete’s foot

Most are harmless - mushrooms Some cause serious problems Tinea pedis - athlete’s foot

How are diseases spread?How are diseases spread?

Physical Contact Direct indirect

Contaminated food and water Food poisoning Fecal-oral

Infected animals Animals, such as mosquitos and ticks, can

be vectors for disease.

Physical Contact Direct indirect

Contaminated food and water Food poisoning Fecal-oral

Infected animals Animals, such as mosquitos and ticks, can

be vectors for disease.

The Lymphatic SystemThe Lymphatic System

How do we fight disease?How do we fight disease?

Antibiotics Compounds that kill

bacteria without harming the infected host cells.

Work by interfering with cellular processes of bacteria

Not effective against viruses

Over-the-counter drugs Treat only the symptoms

Antibiotics Compounds that kill

bacteria without harming the infected host cells.

Work by interfering with cellular processes of bacteria

Not effective against viruses

Over-the-counter drugs Treat only the symptoms

The Immune SystemThe Immune System

The Immune System is the body’s way of fighting infection through Immunity - the production of cells that inactivate foreign substances or cells.

The Immune System is the body’s way of fighting infection through Immunity - the production of cells that inactivate foreign substances or cells.

Non-Specific DefensesNon-Specific Defenses First line of defense - keep pathogens out of

body Skin, mucus, sweat, tears

Second line of defense Inflammatory response - nonspecific defense reaction

to tissue damage caused by injury or infection Fever - A release of chemicals that increase the body’s

core temperature. Slows down or stops growth of pathogens Increases heart rate to get white blood cells to infection faster

Interferons - proteins that interfere with the growth of viruses

First line of defense - keep pathogens out of body Skin, mucus, sweat, tears

Second line of defense Inflammatory response - nonspecific defense reaction

to tissue damage caused by injury or infection Fever - A release of chemicals that increase the body’s

core temperature. Slows down or stops growth of pathogens Increases heart rate to get white blood cells to infection faster

Interferons - proteins that interfere with the growth of viruses

Specific DefensesSpecific Defenses

If a pathogen is able to get past the non-specific defenses of the body, the immune system responds with an immune response - a series of specific defenses that attack a particular disease causing agent.

Antigen - a substance that triggers this response

If a pathogen is able to get past the non-specific defenses of the body, the immune system responds with an immune response - a series of specific defenses that attack a particular disease causing agent.

Antigen - a substance that triggers this response

Humoral ImmunityHumoral Immunity

When a pathogen invades the body, its antigens are recognized by B lymphocytes (B cells) which divide and produce large numbers of B cells and plasma cells

Plasma cells release antibodies, which bind to antigens

Once exposed to a pathogen, millions of B cells remain capable of producing antibodies specific to that pathogen.

When a pathogen invades the body, its antigens are recognized by B lymphocytes (B cells) which divide and produce large numbers of B cells and plasma cells

Plasma cells release antibodies, which bind to antigens

Once exposed to a pathogen, millions of B cells remain capable of producing antibodies specific to that pathogen.

Antibody StructureAntibody Structure

Cell-Mediated ImmunityCell-Mediated Immunity

Viruses and other pathogens cannot be destroyed by antibodies alone

The body’s primary defense against its own cells when they become infected.

Also important in fighting fungi and protists

Viruses and other pathogens cannot be destroyed by antibodies alone

The body’s primary defense against its own cells when they become infected.

Also important in fighting fungi and protists

Acquired ImmunityAcquired Immunity

Active Immunity - appears after exposure to an antigen Vaccination - the injection of a weakened

form of a pathogen to produce immunity

Passive Immunity - antibodies against a pathogen which are produced by other animals are injected into the bloodstream Short-term. Body destroys foreign antibodies

Active Immunity - appears after exposure to an antigen Vaccination - the injection of a weakened

form of a pathogen to produce immunity

Passive Immunity - antibodies against a pathogen which are produced by other animals are injected into the bloodstream Short-term. Body destroys foreign antibodies

Immune System DisordersImmune System Disorders

Allergies Asthma Autoimmune diseases AIDS

Allergies Asthma Autoimmune diseases AIDS

Preventing the Spread of Infectious Disease

Preventing the Spread of Infectious Disease

Chain of Transmission Reservoir Portal of exit Means of transmission Portal of entry Susceptible host

Hand washing Cover your cough Healthy diet Exercise and rest Just say no See the doctor

Chain of Transmission Reservoir Portal of exit Means of transmission Portal of entry Susceptible host

Hand washing Cover your cough Healthy diet Exercise and rest Just say no See the doctor