10.3 Malfunctions of the Immune System

1. 10.3 Malfunctions of the Immune System Allergies • Your immune system mistakes harmless cells for harmful invaders • Hypersensitive (exaggerated) responses to certain environmental antigens (allergens) • Particular cells, that think your body is in danger, release bradykinin which stimulates your WBCs to release histamine (an inflammatory agent)

2. Effects of Histamine • Dilation and increased permeability of small blood vessels • This leads to: • Sneezing, runny nose, tearing eyes, and smooth muscle contractions that can result in breathing difficulty • Antihistamines (reactine, claritin) diminish allergy symptoms by blocking receptors for histamine

3. Anaphylactic Shock • A life-threatening reaction to injected or ingested allergens • Occurs when widespread histamine release triggers abrupt dilation of peripheral blood vessels, causing a sharp drop in blood pressure • Epi Pen  contains the hormone epinephrine which counteracts this allergic response

4. Autoimmune Disease • Sometimes the immune system loses tolerance for self and turns against certain molecules of the body, causing one of the many autoimmune diseases. • Lupus: antibodies generated against histones and DNA  skin rashes, fever, arthritis, and kidney dysfunction • Rheumatoid arthritis  painful inflammation of the cartilage and bone of joints • MS: T cells react against myelin sheath of neurons  neurological abnormalities • Mutated B and T cells?

5. Immunodeficiency Diseases • Suppression of immune system  immune system fails to function • Hodgkin’s disease  suppresses lymphatic system • AIDS  suppresses T cells

6. 10.4 Pathogens and Disease • Diseases can be associated with a foreign microbe that invades the body  pathogen • Contagious diseases are transmitted from person to person (host transfer in different ways)

7. Transmission of Some Common Pathogens

8. Transmission of Disease • Airborne/waterborne infections • Direct contact infections • Vector: a disease-carrying animal

9. Pathogens Bacteria  cause damage to tissues of the body sometimes by the release of poisons or toxins Viruses  activated when DNA is released into living host Prions  abnormally folded proteins that can cause surrounding proteins to assume abnormal shapes

10. 10.5 Induced Immunity • Immunity may be acquired naturally when antibodies are produced in response to a specific infectious invader. • The body takes an active role in making antibodies that destroy the invading antigen, so it is known as active immunity • Immunity may also be acquired when antibodies are introduced to the body, and therefore it is known as passive immunity. This happens as a temporary immunity such as when you need a tetanus shot.

11. Vaccination • Vaccines are antigen-containing substances that can be swallowed or injected to provide immunity to specific diseases. • Vaccinations involve introducing a weakened or dead microbe into the body. • Many vaccinations now are usually produced with the help of recombinant DNA • The proteins that are produced in the lab would have similar structures to the real antigen, and stimulate the response of the person’s immune system without presenting a huge risk. • No antigen lives forever, so some vaccines will require a booster

12. Antibiotics • Antibiotics are a special kind of chemical agent that are usually obtained from living organisms. • Penicillin is a common antibiotic that interferes with the cell wall of bacteria and the cell wall bursts and the cell dies. • Individuals who have very sensitive T-cells identify antibiotics as toxic and the immune system response is activated, thus some people can be allergic to antibiotics.

13. Antibiotic-Resistant Bacteria • Because bacteria divide and grow so quickly, this allows for many mutations and unfortunately there are some bacterial random mutations that have allowed the microbes to become resistant to penicillin and other antibiotics. • One of the main factors in the development of drug-resistant bacteria is the overuse of antibiotics by humans to prevent disease. • Almost any disease-causing agent can be exploited for biological warfare.