Human Body Systems Test

Function of the Immune System

To protect and defend the human body from pathogens

Pathogen

A disease causing organism (bacteria, virus, parasite, fungus)

How are diseases spread?

1. Coughing, sneexing, physical contact

2. Exchange of bodily fluids

3. Contaminated food and water

4. Zoonoses: Transmission from animal to human

Non-specific Human Defenses

• These work in the same manner on any pathogen

• Considered part of your innate immunity (born with it)

Specific Human Defenses

• These are targeted against one particular type of pathogen

• Known as part of your adaptive immunity

Hummoral Immunity

• Part of adaptive immunity

• B-cell lymphocytes produce antibodies

• Antibodies smother pathogens in the blood and lymph, preventing the pathogen from infecting more cells

• Memory cells are produced, making you ‘immune’ to the pathogen in the future (most of the time..)

• Specific human defense

Cell-Mediated Immunity

• Part of the adaptive immunity

• T cells hunt down body cells that have been infected by the pathogen

• T cells either puncture the infected cell with a toxin or initiate apoptosis

• Specific human defense

Vaccines

• Trigger adaptive immunity by injecting an agent of the pathogen into the body

• Trigger hummoral

First Line of Defense

Non-specific External

Barriers of protection to prevent infection include:

• skin

• nose hairs

• tears

• stomach acid

• mucous

• sweat

• saliva

Second Line of Defense

Non-Specific Internal

If a pathogen gets through the first line defenses, the following can occur:

• Inflammatory response

• fever and fatigue

• macrophages

• interferon: disrupts viral reproduction (chemical)(Teraflu)

Third line of defense

Specific Internal

If the pathogen is dividing faster than the 2nd line can keep up with it, the third line kicks into action:

Lymphocytes:

• T-cells alert B-cells into action, which in turn produce antibodies

Hummoral and Cell-mediated.