The Immune SystemThe Immune System

Dr. TimmelDr. Timmel

What is the function of the immune What is the function of the immune system?system?

To fight infection through the production of To fight infection through the production of cells that inactivate foreign substances or cells that inactivate foreign substances or cells.cells.

Some defenses are non-specific and some Some defenses are non-specific and some are specific.are specific.

These defenses work together to both These defenses work together to both prevent and fight off disease.prevent and fight off disease.

What is disease?What is disease?

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

What this really means is that something is What this really means is that something is forcing your body out of equilibrium.forcing your body out of equilibrium.

If an organism is in a disease condition for If an organism is in a disease condition for too long a period of time, death will ensue.too long a period of time, death will ensue.

What are pathogensWhat are pathogens

Pathogens are disease causing agents.Pathogens are disease causing agents.Diseases caused by pathogens are Diseases caused by pathogens are

generally called infectious diseases.generally called infectious diseases.Examples of pathogens are:Examples of pathogens are:

Viruses (the flu, the common cold, warts)Viruses (the flu, the common cold, warts)Bacteria (strep throat, anthrax)Bacteria (strep throat, anthrax)Protists (malaria, sleeping sickness)Protists (malaria, sleeping sickness)Worms (tapeworms)Worms (tapeworms)Fungi (AthleteFungi (Athlete’’s foot)s foot)

Non-specific defensesNon-specific defenses

First line of defense: The bodies most First line of defense: The bodies most important nonspecific defense is the skin.important nonspecific defense is the skin.

This first line of defense also consists of This first line of defense also consists of mucus, sweat and tears.mucus, sweat and tears.

Consists of physical and chemical Consists of physical and chemical defenses.defenses.

Any break in the skin is a possible avenue Any break in the skin is a possible avenue into your body for a disease causing agent.into your body for a disease causing agent.

Second line of defenseSecond line of defense

The inflammatory response. A The inflammatory response. A nonspecific response to tissue damage nonspecific response to tissue damage caused by injury or infection.caused by injury or infection.

Infected tissue may become swollen and Infected tissue may become swollen and painful.painful.

A fever is often a component of the A fever is often a component of the inflammatory response.inflammatory response.

What are antigens?What are antigens?

A foreign substance which triggers a A foreign substance which triggers a response by your immune system.response by your immune system.

Viruses, bacteria and other pathogens are Viruses, bacteria and other pathogens are examples of antigens.examples of antigens.

The antigen is what is making you sick.The antigen is what is making you sick.Allergies are also caused by antigens that Allergies are also caused by antigens that

aren’t really dangerous, but trick your body aren’t really dangerous, but trick your body into acting as if they were. (eg. Pollen).into acting as if they were. (eg. Pollen).

What are antibodiesWhat are antibodies

Antibodies are proteins that recognize and Antibodies are proteins that recognize and bind to antigens, inactivating them.bind to antigens, inactivating them.

Each antibody is specific to a certain Each antibody is specific to a certain antigen.antigen.

Once a particular antibody is produced by Once a particular antibody is produced by a body, memory B-cells become capable a body, memory B-cells become capable of quickly producing them should the body of quickly producing them should the body encounter the same antigen in the future.encounter the same antigen in the future.

VaccinationVaccination

The injection of a weakened or killed form The injection of a weakened or killed form of a pathogen to produce immunity.of a pathogen to produce immunity.

Vaccines give the patient an active Vaccines give the patient an active immunity against a particular disease and immunity against a particular disease and have saved millions of lives.have saved millions of lives.

LymphocytesLymphocytes

As we should recall from the circulatory system, there As we should recall from the circulatory system, there are four different types of white blood cells.are four different types of white blood cells.

T-Cells: Provide a defense against abnormal cells and pathogens inside living cells. T-Cells: Provide a defense against abnormal cells and pathogens inside living cells. T-Cells are formed in the Thymus gland. 2 types: Helper and Killer T cells.T-Cells are formed in the Thymus gland. 2 types: Helper and Killer T cells.

B-Cells: Provide immunity against pathogens and antigens in the body fluids. B-B-Cells: Provide immunity against pathogens and antigens in the body fluids. B-Cells are formed in the Bones. These cells produce the antibodies that either disable Cells are formed in the Bones. These cells produce the antibodies that either disable or destroy the pathogen.or destroy the pathogen.

Phagocytes: Cells that devour foreign cells through phagocytosisPhagocytes: Cells that devour foreign cells through phagocytosis

Macrophages: Very large phagocytes. Assist the activation of B and T Cells.Macrophages: Very large phagocytes. Assist the activation of B and T Cells.

Autoimmune diseaseAutoimmune disease

When the bodyWhen the body’’s own immune system s own immune system attacks itattacks it’’s own cells.s own cells.

The immune system produces The immune system produces ““antiselfantiself”” antibodies.antibodies.

Examples are type one diabetes, MS and Examples are type one diabetes, MS and AIDS.AIDS.

AIDSAIDS

Acquired Immune Deficiency Syndrome.Acquired Immune Deficiency Syndrome.

A viral disease in which the bodyA viral disease in which the body’’s T-cells s T-cells are destroyed, leaving the body are destroyed, leaving the body susceptible to secondary infections.susceptible to secondary infections.

Causes by the HIV (Human Causes by the HIV (Human immunodeficiency virus). It is a retrovirus, immunodeficiency virus). It is a retrovirus, meaning it contains RNA and not DNAmeaning it contains RNA and not DNA

What is lymph?What is lymph?

It is a clear fluid that is lost by the blood to It is a clear fluid that is lost by the blood to the surrounding tissue.the surrounding tissue.

Travels through the lymphatic system: A Travels through the lymphatic system: A network of vessels, nodes and organs network of vessels, nodes and organs which collects fluids and returns them to which collects fluids and returns them to the circulatory system.the circulatory system.

Contains a large number of white blood Contains a large number of white blood cells.cells.

What are lymph nodes?What are lymph nodes?

Part of the lymphatic system, lymph nodes Part of the lymphatic system, lymph nodes are small bean shaped enlargements that are small bean shaped enlargements that filter the lymph and capture bacteria and filter the lymph and capture bacteria and other microorganism that cause disease.other microorganism that cause disease.

When the doctor says you have swollen When the doctor says you have swollen glands, they are actually referring to your glands, they are actually referring to your lymph nodes. They get larger when you lymph nodes. They get larger when you are fighting an infection.are fighting an infection.

Other organs of the immune Other organs of the immune systemsystem

In addition to lymphocytes, lymph and In addition to lymphocytes, lymph and lymph nodes, one gland and one other lymph nodes, one gland and one other organ play important roles.organ play important roles.

Thymus gland. As mentioned earlier, T-Thymus gland. As mentioned earlier, T-Cells mature in the thymus gland.Cells mature in the thymus gland.

Spleen: helps to cleanse the blood and Spleen: helps to cleanse the blood and remove damaged cells from the circulatory remove damaged cells from the circulatory system. Also contains phagocytes.system. Also contains phagocytes.