The Immune System

What is the immune system?

• The immune system is the body's natural defense system that helps fight infections.

Components of the Immune System

• anitbodies
• white blood cells
• other chemicals and proteins that attack bacteria and viruses that is recognized as foreign and different from body's normal healthy tissues

Other Components of Immune System

• lymph nodes and vessels (lymphatic system)
• bone marrow
• spleen
• white blood cells

Lymphatic System

• network carries lymph fluid, nutrients, and waste material between the body tissues and the bloodstream
• lymph fluid traps bacteria, viruses, and other foreign substances
• then destroyed by special white blood cells called lymphocytes

Bone Marrow

• soft tissue found mainly inside long bones of arms and legs
• made of red marrow, which prodcues red and white blood cells and platelets
• yellow marrow contains fat and connective tissue and produces some white blood cells

Spleen

• filters blood by removing old or damaged blood cells and platelets
• helps the immune system by destroying bacteria and other foreign substance

White Blood Cells

• blood cells made in the bone marrow and protect the body against infection
• if an infection develops, white blood cells attack and destroy the bacteria, virus, or other organism causing it

Innate Immunity

• present at birth and does not have to be learned through exposure to an invader
• It thus provides an immediate response to foreign invaders
• components treat all foreign invaders in much the same way

Adaptive Immunity

• refers to antigen-specific immune response
• more complex than the innate immunity
• antigen first must be processed and recognized
• Once an antigen has been recognized, the adaptive immune system creates an army of immune cells specifically designed to attack that antigen.

B-lymphocytes

• produced in the bone marrow
• A type of white blood cell
• many mature into plasma cells
• others become memory B cells
• A type of white blood cell

B-lymphocytes (cont.)

• All plasma cells descended from a single B cell produce the same antibody which is directed against the antigen that stimulated it to mature.
• The same principle holds with memory B cells.
• all of the plasma cells and memory cells "remember" the stimulus that led to their formation

T-lymphocytes

• A type of white blood cell that is of key importance to the immune system and is at the core of adaptive immunity
• like soldiers who search out and destroy the targeted invaders
• T cells can produce substances called cytokines such as the interleukins which further stimulate the immune response.

T-lymphocytes (cont.)

• Immature T cells migrate to the thymus gland in the neck, where they differentiate into various types of mature T cells and become active in immune system in response to a hormone called thymosin and other factors. T-cells that are potentially activated against body's own tissues are normally killed or changed during this maturational process

The Immune Response (Pt. 1)

• when antigens (foreign substances that invade the body) are detected, several types of cells work together to recognize them and respond. These cells trigger the B lymphocytes to produce antibodies, specialized proteins that lock onto specific antigens.

The Immune Response (Pt. 2)

• Once produced, these antibodies continue to exist in a person's body, so that if the same antigen is presented to the immune system again, the antibodies are already there to do their job

The Immune Response (Pt. 3)

• Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it without help. T cells are part of the system that destroys antigens that have been tagged by antibodies or cells that have been infected or somehow changed. T cells are involved in helping signal other cells (like phagocytes)

Autoimmune Diseases

• abnormally low activity or over activity of the immune system
• Over Activity-body attacks its own tissues
• Immune Deficiency-decrease the body's ability to fight invaders, so vulnerability to infections

Summary of Immune System

• The human immune system is a truly amazing constellation of responses to attacks from outside the body
• It has many facets, a number of which can change to optimize the response to these unwanted intrusions

Summary of Immune System (cont.)

• An antigen is any substance that elicits an immune response, from a virus to a sliver
• The immune system has a series of dual natures, the most important of which is self/non-self recognition
• Parts of the immune system are antigen-specific (they recognize and act against particular antigens)

Works Cited

• "Immune System." N.p., n.d. Web. 16 Mar. 2015.
• "Autoimmune Diseases: What Are They? Who Gets Them?" WebMD. WebMD, n.d. Web. 12 Mar. 2015.
• "T Cell Defintion." MedicineNet, n.d. Web. 16 Mar. 2015.
• "B Cell Definition." MedicineNet, n.d. Web. 16 Mar. 2015

Works Cited (cont.)

• "Introduction to Immunology Tutorial." Introduction to Immunology Tutorial. The Biology Project, n.d. Web. 16 Mar. 2015.

The End