Fighting Disease

1. Fighting Disease

2. Pathogens • Pathogen is any disease causing microorganism, that cause a response from the body • Bacteria cause disease by releasing toxins into the body • Viruses cause disease by taking over and destroying cells

3. Immune-System Response External Responses – First line of Defense • Skin provides an almost impenetrable barrier against pathogens • sweat contains amino acids that are poisonous to bacteria found on skin • Tears contain enzymes that breakdown bacteria

4. External Defenses • Respiratory tract contains mucus secreting cells that trap pathogens • Cilia then are able to sweep out the pathogen • Stomach acid destroys bacteria

5. The Lymphatic System • The second line of defense • Complex network of organs that work to get rid of any pathogens that got past the external barriers

6. Lymphatic system is made up of vessels and nodes Vessels move around lymph, a white fluid containing white blood cells called lymphocytes Nodes and the spleen filter out microorganisms, preventing them from entering the blood stream

7. Core of bones contains marrow Marrow makes white blood cells called macrophages These cells are able to travel throughout the body to infection sites and destroy pathogens

8. Antibody Formation • When the body recognizes a pathogen it creates an antibody specific to it • The antibody attaches to the outside of the pathogen, which inactivates it • This complex sends a signal to the white blood cells that makes it easier for the cell to recognize and destroy it

9. Active Immunity • Natural Immunity, body recognizes a pathogen because is has suffered from it before • Vaccines where dead or weakened cells are injected. The body reacts as it is a real infection and produces antibodies

10. Passive Immunity • Antibodies can be introduced directly into the bloodstream • Ex. • From mother to child through breast milk • Vaccinations that contain plasma from one animal that has had the disease