1. Systems of Defense Animal Systems

2. Think about it… What challenges would a burn victim face? What challenges would a burn victim face? What would happen if you didn’t have skin? What would happen if you didn’t have skin? What do you think is the purpose of skin? What do you think is the purpose of skin?

3. Why do we need skin? Protection from injury 1 st Line of Defense against Disease Prevents the body from drying out

4. How is it that we often bump our heads, either by accident or on purpose, without sustaining serious injury to our brain?

5. Why do we need bones? Bone marrow Spongy bone Compact bone Blood vessels Periosteum Provides shape & support Protects internal organs Along with muscles, enables movement.

6. Both of these provide defense and protection to the animal. What do we need protection from? Injury & Illness How do they protect us? Provides a physical barrier A physical barrier from what???

7. 1st Line of Defense Skin and mucous membranes are the 1st Line of Defense against pathogens! What are pathogens? An agent that causes disease. Examples: viruses, bacteria, fungi, protists

8. Viruses Non-living. Why? Needs a host cell to replicate Do not grow, metabolize, or maintain homeostasis. Viruses are specific to certain kinds of cells. Ex: HIV infects only Helper T cells Before a virus can replicate, it must attach to and infect a living cell, called the host cell.

9. Common Viral Infections Cold soresHerpes Influenza (the flu)HIV/AIDS SARS Small pox Viral pneumoniaWarts Chicken poxHepatitis

10. Bacteria Remember Bacteria? Prokaryotes-No nucleus Can be harmful (cause disease) or helpful (food-making, mining, nitrogen fixing for the environment)

11. How do Bacteria cause disease? Bacteria can cause disease by metabolizing nutrients in their host (competition for resources) or by releasing toxins, which damage the host. Bacteria are identified by their shape and cell wall type.

12. Important Bacterial Infections Ear infections Upper Respiratory Infection Cavities Stomach Ulcers Tuberculosis Impetigo Carbuncles Food Poisoning

13. How can we treat infections? Only bacterial infections can be treated with an antibiotic. Why? Let’s look at the word— Unfortunately, viruses can only be treated with rest and fluids until your immune system destroys the cells infected with viruses. againstlife

14. What other methods are used to protect against pathogens? Prevention by vaccines! How does it work? How does it work? A weakened or heat-killed strain of a virus or bacteria is injected into your body. Your immune system responds to the vaccine by creating B cells, the memory cells. If the pathogen enters your body again, it is quickly recognized and destroyed.

15. What happens if the pathogen gets past the 1 st Line of Defense? 2 nd Line of Defense!!

16. Second Line of Defense White Blood Cells Phagocytic immune cells (neutrophils and macrophages) engulf and destroy pathogens Inflammatory Response Swelling and increased blood flow Delivers more white blood cells to the area of injury Temperature Response (fever) Bacteria can only grow within a certain temperature range. A fever raises the temperature so the bacteria cannot survive.

17. What if the 2 nd Line of Defense doesn’t stop the pathogen? Specific Immune Response- 3 rd Line of Defense What does it mean to be SPECIFIC? def: of a special or particular kind Then what is a specific immune response?

18. How does the body recognize pathogens? Body cells have surface markers that indicate they belong in the body. When a pathogen infects a body cell, the infected body cell displays an antigen on the surface. The antigen triggers an immune response. Like little red flags Like an ID Badge

19. So how does it work? Helper T cells recognize the antigens that are given off by macrophages that have ingested pathogens. The helper T cells then activate B cells and cytotoxic t cells. B cells become memory cells that help recognize the pathogen as soon as it is reintroduced to the body. Cytotoxic T cells destroy infected cells

20. Reflection: On the left hand side of your IN, write a description of the body defenses that are involved in the following scenario: Joe was slicing an apple when the knife slipped and sliced his thumb. Ouch!