Biology...defenses of the body against bacteria, diseases...etc.

Notes The skin provides the first defense against invasion by pathogens. Skin acts as a wall that keeps pathogens out of the body. Secretions of the oil and sweat glands within the dermis make the skin's surface very acidic, inhibiting the growth of many pathogens. Sweat also contains the enzyme lysozyme, which attacks and digests the cell walls of many bacteria. Internal surfaces of the body though which pathogens could pass are covered by mucous …

…system attacks and destroys the sheath of myelin that insulates motor nerves, which carry commands from the brain to the muscles and organs. Degeneration of the myelin sheath interferes with the transmission of nerve impulses, ultimately stopping their transmission altogether. Voluntary functions, such as the movement of limbs, and involuntary functions, such as bladder control, are lost, leading to paralysis, and eventually, death. Scientists do not know what stimulates the immune system to attack myelin.