The Immune System is a group of cells, molecules, and organs that act together to defend against disease. The body depends on the immune system to seek and destroy bacteria or viruses that could cause harm.There are two types of immunity: innate and adaptive. Innate is the body’s first line of a defense against the disease. The innate immunity helped by barriers such as skin, tears, mucus, saliva, and infection. But the innate can’t usually prevent disease completely. After the disease has passed through this it has a specific immunity which is known as adaptive immunity. The adaptive immunity has four parts. First it responds only after the invader is present. Second, it uses its response to act on a specific type of disease. After this it uses memory and responses better than the first time it attacks. It attacks the substances, which are harmful. There are two types of adaptive system reponses: humoral and cell meditated. In the humoral immune response proteins, which can stick and destroy antigens appear in the blood and other body fluids. Humoral immune responses resist invaders that act outside of cells such as bacteria or toxins. During cell meditated immune responses cells that can destroy other cells become active. Their destructive activity is limited to cells that are either infected with or producing a specific antigen. Cell meditated immune responses resist invaders that reproduce within the body cells such as viruses. Cell meditated responses may also destroy cells making mutated forms of normal molecules as in some cancers. Diseases and how they can be control. When people refer to pathogens, they are talking about bacteria that cause disease. The toxins actually excreted by the pathogens are the main cause of diseases although the toxins are only by-products of the pathogen's metabolism. In most cases, the toxins excreted by the pathogens find there way into the circulatory system. Thus, sometimes, the...
