Immune System

Disease A disease is any change other than injury, that disrupts the normal functions of the body. Some diseases are inherited, others are caused by materials in the environment. A disease is any change other than injury, that disrupts the normal functions of the body. Some diseases are inherited, others are caused by materials in the environment. Still others are caused by agents such as bacteria, viruses, fungi, animals such as worms, etc.. Still others are caused by agents such as bacteria, viruses, fungi, animals such as worms, etc..

Pathogens Disease-causing agents such as bacteria are called pathogens. (sickness makers) Disease-causing agents such as bacteria are called pathogens. (sickness makers) Diseases caused by pathogens are called infectious diseases, because the agents that cause infect the body they enter. Diseases caused by pathogens are called infectious diseases, because the agents that cause infect the body they enter.

Toxins Toxins are poisons that produce illness by disrupting bodily functions. Toxins are poisons that produce illness by disrupting bodily functions. Some bacteria cause disease by producing toxins and injecting them into host cells. Some bacteria cause disease by producing toxins and injecting them into host cells. Animals that carry disease-causing organisms from person to person are called vectors. Animals that carry disease-causing organisms from person to person are called vectors.

Antibiotics Antibiotics are compounds that kill bacteria without harming the cells of humans or animals. Antibiotics are compounds that kill bacteria without harming the cells of humans or animals. Antibiotics work by interfering with the cellular processes of microorganisms. Antibiotics work by interfering with the cellular processes of microorganisms. They have no affect on viruses They have no affect on viruses Penicillin was discovered in 1928 by Alexander Fleming. Penicillin was discovered in 1928 by Alexander Fleming. xander-fleming xander-fleming xander-fleming xander-fleming

Vaccines Killed or weakened viruses. Killed or weakened viruses. The injection of a weakened or mild form of a pathogen to produce immunity is known as a vaccination. The injection of a weakened or mild form of a pathogen to produce immunity is known as a vaccination. Today more than 20 serious human diseases can be prevented by vaccinations. Today more than 20 serious human diseases can be prevented by vaccinations.

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First Line of Defense The body has several physical barriers: The body has several physical barriers: An outer layer of intact skin An outer layer of intact skin Hair in the nostrils Hair in the nostrils Mucous membranes Mucous membranes Cilia Cilia Mucus in your nose or throat traps viruses and bacteria Mucus in your nose or throat traps viruses and bacteria Stomach acids and digestive enzymes destroy many pathogens. Stomach acids and digestive enzymes destroy many pathogens. Mucus, saliva, sweat, tears contain an enzyme that breaks down the cell walls of many bacteria. Mucus, saliva, sweat, tears contain an enzyme that breaks down the cell walls of many bacteria.

Cilia

Second Line of Defense The inflammatory response is a defense reaction to tissue damage caused by injury or infection. The inflammatory response is a defense reaction to tissue damage caused by injury or infection. White blood cells leak from the vessels to enter the infected tissues. They engulf and destroy bacteria. White blood cells leak from the vessels to enter the infected tissues. They engulf and destroy bacteria. The infected tissue may become swollen and painful. The infected tissue may become swollen and painful.

The Immune Response If a pathogen is able to get past the body’s first few lines of defense the immune system reacts with a series of specific defenses that attack disease- causing agents. If a pathogen is able to get past the body’s first few lines of defense the immune system reacts with a series of specific defenses that attack disease- causing agents. A substance that triggers this response is called an antigen. A substance that triggers this response is called an antigen.

White Blood Cells Leukocytes (White blood cells) Leukocytes (White blood cells) Macrophages Macrophages Lymphocyte (B cells, T cells, & cytotoxic) Lymphocyte (B cells, T cells, & cytotoxic) Basophil (release of histamine and inflammatory response) Basophil (release of histamine and inflammatory response) Video Clip

Third Line of Defense Antibodies Antibodies –Antigens Are foreign substances that cause an immune response. Are foreign substances that cause an immune response. –Antibodies Are proteins found in blood plasma that attach to one particular kind of antigen and help counter its effects. Are proteins found in blood plasma that attach to one particular kind of antigen and help counter its effects.

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Permanent Immunity Once the body has been exposed to a pathogen, millions of memory B and T cells remain capable of producing specific antibodies to that pathogen. Once the body has been exposed to a pathogen, millions of memory B and T cells remain capable of producing specific antibodies to that pathogen.

Immune System Disorders Allergies result when antigens from allergens (pollen, dust ball, dust mites) bind to a type of immune cells. The immune cell becomes activated and produces a chemical called histamine. Allergies result when antigens from allergens (pollen, dust ball, dust mites) bind to a type of immune cells. The immune cell becomes activated and produces a chemical called histamine. Histamines increase the flow of blood and fluids to the surrounding area. They produce the sneezing, runny eyes and nose. Histamines increase the flow of blood and fluids to the surrounding area. They produce the sneezing, runny eyes and nose. Antihistamines are drugs that are used to counteract the effects of histamines. Antihistamines are drugs that are used to counteract the effects of histamines. Video

Autoimmune Disease When the immune system makes a mistake and attacks the body’s own cells, it produces an autoimmune disease. When the immune system makes a mistake and attacks the body’s own cells, it produces an autoimmune disease.

A.I.D.S. –HIV, the AIDS virus Attacks helper T cells Attacks helper T cells –HIV has one of the fastest rates of mutation of any pathogen ever studied. –Drug-resistant HIV strains are now being documented in newly infected patients. –Exhibits how this virus readily adapts through natural selection.