Immunity: Part I Body Defenses Against Infection

1. Immunity: Part IBody Defenses Against Infection

2. What is immunity? • The body’s defense against disease causing organisms, malfunctioning cells, and foreign particles Video

3. Overview of Immunity: • Reconnaissance, Recognition, and Response • Two major kinds of defense have evolved that counter threats: • Innate immunity • Adaptive immunity

4. 3m Innate Immunity • Is present before any exposure to pathogens and is effective from the time of birth • Involves nonspecific responses to pathogens • aka. Nonspecific Defenses or Innate Immunity

5. Innate Immunity Includes: • Species resistance • Physical barriers • Phagocytic cells • Immunological surveillance • Interferons • Complement system • Inflammation • Fever

6. Adaptive Defenses • Also called: • Specific defenses • Specific immunity • Acquired immunity • Develops only after exposure to inducing agents such as microbes, toxins, or other foreign substances (acquired) • Involves a very specific response to pathogens

7. Innate Immunity

8. aka. Mechanical Barriers

9. External Defenses~Skin~ • The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals that kill potential invaders • You shed between 40 – 50 thousand skin cells every day!

10. External Defenses: Hair http://www.hairdirect.com/hair/systems/skin/hd10.aspx http://www.hmh.net/adamhealth/In-Depth%20Reports/10/000032.htm

11. Secretions of the skin and mucous membranes • Provide an environment that is often hostile to microbes • Secretions from the skin • Give the skin a pH between 3 and 5, which is acidic enough to prevent colonization of many microbes • Also include proteins such as lysozyme, an enzyme that digests the cell walls of many bacteria

12. Sweat Tears http://creativephotographymagazine.com/30-heart-touching-photographs-of-tears/ • http://www.examiner.com/article/wiping-your-sweat-away-can-actually-make-your-workout-harder

13. External Defenses~Mucous and Cilia~ • As you breathe in, foreign particles and bacteria bump into mucus throughout your respiratory system and become stuck

14. External Defenses~Mucous and Cilia~ • Hair-like structures called cilia sweep this mucus into the throat for coughing or swallowing

15. External Defenses~Saliva~ • Saliva contains many chemicals that break down bacteria • Thousands of different types of bacteria can survive these chemicals, however

16. External Defenses~Stomach Acid~ • Swallowed bacteria are broken down by incredibly strong acids in the stomach that break down your food • The stomach must produce a coating of special mucus or this acid would eat through the stomach!

17. Urinary Tract • Urine flushes the urinary passageways

18. Reproductive Tract • Glandular secretions flush structures of the reproductive system

19. Think of the human body as a hollow plastic tube… Substances enter within the hole in the tube, but it never actually enters into the solid plastic material directly. Tube inner surface ~Digestive System~ Tube outer surface ~Skin~ Plastic interior ~Body~

20. These bacteria are technically outside the body and aid in digesting material we cannot • Only if E.Coli are introduced in an unnatural manner can they break through the first line of defense and harm us Escherichia coliis common and plentiful in all of our digestive tracts. Why are we all not sick?