Immune System

Immune System - What Are the Major Defense Systems of...

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What Are the Major Defense Systems of Animals? * Animal defenses against pathogens are based on the body’s ability to distinguish between self and nonself. * Specific defenses are adaptive mechanisms that respond to specific pathogens. They develop more slowly than nonspecific defenses but are long-lasting. * Many defenses are implemented by cells and proteins carried in the blood plasma and lymph. * White blood cells fall into two broad groups. Phagocytes include macrophages that engulf pathogens by phagocytosis. Lymphocytes, which include B cells and T cells, participate in specific responses. What Are the Characteristics of the Nonspecific Defenses? * An animal’s nonspecific defenses include physical barriers such as the skin. * Circulating defensive cells, such as phagocytes and natural killer cells, eliminate invaders. * The inflammation response activates several types of cells and proteins that act against invading pathogens. Mast cells release histamines, which cause blood vessels to
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Immune System - What Are the Major Defense Systems of...

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