Body Defenses

1. Body Defenses Chapter 15 Page 279

2. Agglutinins Antibodies Antigens Antitoxins Erythrocytes Exotoxin Escheriachia coli hemolysin Incubation period Inflammation Leukocytes Lyse Lysosome Opsonins Phagocytosis Precipitins Vocabulary

3. Three main defenses • The skin and mucous membrane • Circulatory defenses • Antibodies (immune response)

4. Skin and Mucous Membrane • Skin • Mucous Membrane • Respiratory tract • Digestive tract • Genitourinary tract

6. Skin and Mucous Membrane • The skin kills or inhibits bacterial growth through its secretions • Lactic acid from the sweat glands and fatty acids from the sebaceous (fat) glands and the low pH environment that they produce fight off many pathogens

7. Respiratory Tract • The mucous membranes and the cilia filter and trap inhaled dust and pathogens • Coughing, sneezing, swallowing eliminate bacteria from the body • Lysozyme enzyme found in nasal secretions, saliva, and tears lyses certain gram-positive bacteria

8. Digestive Tract • Pathogens are destroyed by digestive juices, the acidity of the stomach, and the alkalinity of the intestines • Not all bacteria are harmful • Escherichia coli (aides in production of Vitamin K) • Enterobacteraerogenes

9. Genitourinary Tract • Flushes out pathogens by frequent urination and vaginal mucosal secretions • Birth control pills and antibiotics can kill normal vaginal flora and cause risk of infection

10. Circulatory Defenses • If pathogens break through the first line of defense, the other defenses move in to destroy them • Phagocytes • Antibodies • Interferon

11. Phagocytes • Phagocytes are cells of the reticuloendothelial system • Capable of phagocytosis • Fixed • Mobile

12. Phagocytosis – amoeboid-like movement of white blood cells to approach, surround, and engulf foreign material • Necessary to remove dead blood cells, pathogens, and dust particles

14. Phagocytes • Fixed • Attached firmly to liver, spleen, bone marrow, and lymph nodes, linings of intestines and blood vessels (reticuloendothelial system) • Mobile • “wandering phagocytes” leukocytes or white blood cells, they migrate to injured site

15. Antibodies • If pathogens break through the first and second line of defense, antibodies take over

16. Antibodies • Incubation period = time of the foreign antigen invading the body and the onset of the disease

17. Antibodies • Antigens = Pathogens that stimulate the production of antibodies in the blood and the lymph

18. Antibodies • Complement = special proteins that circulate in the liquid portion of the blood in an inactive form until needed

19. Antibodies • Antitoxins- neutralize toxins • Agglutinins- cause bacteria clump together • Lysins- cause the bacteria to dissolve • Opsonins- make them more readily prey to be ingested by phagocytes • Precipitins- cause bacteria to settle out of the bloodstream so threat they can filtered out and destroyed

20. Infection • Local infection • Restricted to one area • General infection • One that has spread to many parts of the body • Recognized by finding bacteria in the bloodstream