Day 2- The Immune System

What are we learning today? Benchmark(s) SC.912.L.14.52 Explain the basic functions of the human immune system, including specific and nonspecific immune response, vaccines, and antibiotics. (AA) SC.912.L.14.6 Explain the significance of genetic factors, environmental factors, and pathogenic agents to health from the perspectives of both individual and public health. HE.912.C.1.4 Analyze how heredity and family history can impact personal health. HE.912.C.1.8 Analyze strategies for prevention, detection, and treatment of communicable and chronic diseases. Students will… Identify and/or explain the basic functions of the human immune system, including specific and nonspecific immune responses. Describe how the human immune system responds to vaccines and/or antibiotics. Explain the significance of genetic factors, environmental factors, and pathogenic agents to health from the perspective of both individual and public health.

Essential Question Your body has several lines of defense against disease. Explain your body’s mechanisms for keeping you healthy. (include nonspecific and specific response)

Interferon Interferon is a protein made and released by host cells in response to the presence of pathogens such as viruses, bacteria, parasites or tumor cells. They allow communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors. They increase the ability of uninfected host cells to resist new infection by virus

Innate immunity Innate (natural) immunity (2nd line of defense) is so named because it is present at birth and does not have to be learned through exposure to an invader. It thus provides an immediate response to foreign invaders. However, its components treat all foreign invaders in much the same way. Innate immunity, unlike acquired immunity, has no memory of the encounters, does not remember specific foreign antigens, and does not provide any ongoing protection against future infection.

What is Acquired Immunity? Acquired (adaptive or specific) immunity (3rd line of defense) is not present at birth. It is learned. As a person's immune system encounters foreign substances (antigens), the components of acquired immunity learn the best way to attack each antigen and begin to develop a memory for that antigen. Acquired immunity is also called specific immunity because it tailors its attack to a specific antigen previously encountered. Its hallmarks are its ability to learn, adapt, and remember. Acquired immunity takes time to develop (7-10 days) after first exposure (primary response) to a new antigen. However afterward, the antigen is remembered, and subsequent responses (secondary response) to that antigen are quicker and more effective than those that occurred after the first exposure.

Primary vs Secondary response Notice the secondary response (memory cells used) for antigen A is more rapid and much stronger than the primary response. (memory cells made, Plasma cells release Antibodies) This is because the Memory cells release the antibodies more quickly than the B-cells when they first encounter the antigen (primary response)

What is Smallpox? Smallpox was once found throughout the world. Caused illness and death wherever it occurred. Smallpox spreads easily from one person to another. People were once vaccinated against this disease. The United States stopped giving the smallpox vaccine in 1972. In 1980, the World Health Organization (WHO) recommended that all countries stop vaccinating for smallpox. The vaccine is no longer given to the general public because the virus has been wiped out. Or has it?

The last naturally occurring case of smallpox was diagnosed on 26 October 1977. In ordinary type smallpox the bumps are filled with a thick, opaque fluid and often have a depression or dimple in the center.

What is an Acquired Immunity? More than 200 years ago, the English physician Edward Jenner wondered if it might be possible to produce immunity against smallpox. Jenner knew that people who had been affected by a mild disease called cowpox developed an immunity to smallpox.

What is Acquired Immunity? Jenner took fluid from one of the sores of a cowpox patient and put the fluid into a small cut that he made on the arm of a young farm boy named Jamie Phillips. Two months later, he injected Jamie with fluid from a smallpox infection and … The rest is history. Briefly discuss medical ethics?

Vaccination (artificial active immunity) The injection of a weakened form of a pathogen to produce immunity is known as vaccination. Today, more than 20 serious human diseases can be prevented by vaccination. Modern vaccines stimulate the immune system to create millions of memory cells (type of B cell) ready to produce a specific types of antibodies (Primary Response). The type of immunity produced by the body’s reaction to a vaccine is known as artificial active immunity. Active immunity may develop as a result of natural exposure to an antigen or from deliberate exposure (artificial) to the antigen. Flu shot, small pox vaccine, Hep B

What is Passive Immunity? If antibodies produced by other animals against a pathogen are injected into the bloodstream of a human, the antibodies produce artificial passive immunity against the pathogen. Passive immunity lasts only a short time because eventually the body destroys the foreign antibodies and your body did not produce the memory cells needed for future protection. Natural passive immunity occurs when antibodies produced by the mother are passed to the offspring during development or in early infancy through breast milk. Artificial passive immunity occurs when travelers to certain regions of the world are given antibodies serum (blood plasma) from another source before leaving home.

Fighting Infectious Diseases Because prevention is not always possible, drugs have been developed for the use against some types of pathogens. Antibiotics are compounds that kill bacteria without harming the cells of the human or animal host and work by interfering with the cellular processes of microorganisms. Antibiotics have no effect on viruses.

What is Methicillin-resistant Staphylococcus aureus (MRSA)? Is a bacterium responsible for several difficult-to- treat infections in humans. MRSA is any strain that has evolved resistance to antibiotics, which include the penicillins (methicillin, dicloxacillin, ampicillin, oxacillin, etc.) Resistance does make MRSA infection more difficult to treat thus more dangerous. MRSA is especially troublesome in hospitals and nursing homes, where patients with open wounds, invasive devices, and weakened immune systems are at greater risk of infection than the general public.

Mueller Hinton agar showing MRSA resistant to oxacillin disk A ruptured MRSA abscess

A B 2 1 2 1 Antibiotic resistance tests: Which ones are sensitive to antibiotics and which ones are resistant? 5 4 3 5 4 3 7 6 7 6

HIV and Viral replication

Infectious Situation Body’s Line of Defense Bacteria and pathogen on skin surface First line of Defense Skin cells with no gaps or cuts keep out pathogens. Sweat acids kill bacteria. Pathogens shed with old skin. Pathogens in nose, mouth, or eyes Pathogens in digestive tract Pathogens in burn or cut Influenza virus enters body for second time Chickenpox virus enters body for second time Measles virus enters body long after measles vaccine Rabies pathogens enter body from rabid dog bite

Essential Question Your body has several lines of defense against disease. Explain your body’s mechanisms for keeping you healthy. (include nonspecific and specific response)

Sample EOC item Which of the following statements best describes the relationships among possible environmental influences, the p53 gene, and cancer? A. Environmental influences can lead to mutations in the p53 gene, which can cause certain cancers. B. Increased levels of p53 protein, rather than environmental influences, can cause certain cancers. C. Mutations in the p53 gene increase environmental influences that can cause certain cancers. D. Genes such as p53 are less causal than environmental influences in stimulating certain cancers.