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