Immune Response LN 13 Body Response Your body

Immune Response LN #13

Body Response • Your body responds to pathogens in several different ways. • Body has specific responses and nonspecific responses • Specific responses – Occur at cellular level; different for each pathogen • Nonspecific responses – Same for every pathogen – Imflammation and fever

Nonspecific Response: Inflammation • Pin breaks the skin and infects with bacteria. • The damaged cells release chemical alarm signals. l. Blood flow to the area increases and causes swelling. l. Chemicals attract phagocytes and other white blood cells to the area. • Phagocytes destroy the bacteria.

Nonspecific Response: Fever • White blood cells (mast cells or macrophages) signal the brain to increase the bodies temperature until the infection is controlled. • Low fevers 100°F (37. 7°C) – Stimulate production of Interferons (prevent viruses from reproducing) – Increase activity of white blood cell maturation • High fevers 103°F (39°C) – Are dangerous – Enzymes stop functioning – Can cause seizure, brain damage and death

Specific Response • Lead to acquired immunity • Occur at cellular level • For specific responses to work your body needs to be able to tell the difference between your cells and pathogens. – Antigens are protein markers on the surface of cells and pathogens. They help your body identify your cells and pathogens.

Specific Immune Response • Depends on T cells • There are two types: helper and killer • Helper T Cell – Function: activates B cells and killer T cells – Helper T cells also need to be activated by binding to antigens on the surface of phagocytes

Helper T Cell Activation 1. A phagocyte “eats” a bacteria 2. Parts of the bacteria (antigen) goes into the surface of phagocyte 3. Phagocyte presents the antigen to helper T cell 4. Helper T cell is activated and goes on to activate B cells and killer T cells

Killer T Cells • • Activated by helper T Cells Specialized to attack infected body cells and cancer cells Recognizes infected cells by the antigens on its surface. Once a cells is recognized as infected it is quickly killed.

B cells 1. The B cell finds an antigen which matches its receptor 2. It waits until it is activated by a helper T cell 3. Then the B cell divides to produce plasma and memory cells

B Cells in Action 4. Plasma cells produce antibodies that attach to the current type of invader 5. “Eater cells” prefer intruders marked with antibodies, and “eat loads of them 6. If the same intruder invades again memory B and T cells help the immune system attack much faster

Lymphatic System • Function – Site where B and T cells migrate to – Transportation and storage of B and T cells – Filters out dead cells and invading pathogens