Bio Chapter 42

- Recognition Phase: Organism must be able to discriminate b/w self and nonself
- Activation Phase: Recognition event leads to a mobilization of cells and molecules to fight the invader
- Effector Phase: Mobilized cells and molecules destroy the invader

- Innate defenses
- Provide the first line of defense against pathogens. They typically act very rapidly, and include barriers such as the skin, molecules that are toxic to invaders, and phagocytic cells that ingest invaders.
- System recognizes broad classes of organisms or molecules and gives a quick response, within minutes or hours.

- Defensive reactions of the vertebrate immune system that are based on the reaction of an antibody to a specific antigen.
- Adaptive mechanisms aimed at specific pathogens.
- Systems recognize specific configurations of atoms in a molecule and are typically slow to develop and long-lasting. Specific defense mechanisms are found in vertebrate animals.

Tissues of the immune system that are dispersed throughout the body, consisting of the thymus, spleen, bone marrow, and lymph nodes.

- Complex systems with nondefensive functions
- Yellowish solution containing ions, small molecular solutes, and soluble proteins.
- Suspended in the plasma are red blood cells, white blood cells, and platelets (cell fragments essential to blood clotting). While red blood cells are normally confined to the closed circulatory system (the heart, arteries, capillaries, and veins), white blood cells and platelets are also found in the lymph.

- A fluid derived from blood and other tissues that accumulates in intercellular spaces throughout the body and is returned to the blood by the lymphatic system.
- Complex systems with nondefensive functions