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Unit Two Immune System. Pathogens Cause Disease It is important to understand people become ill due to two main reasons: – Improper function of internal.

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Presentation on theme: "Unit Two Immune System. Pathogens Cause Disease It is important to understand people become ill due to two main reasons: – Improper function of internal."— Presentation transcript:

1 Unit Two Immune System

2 Pathogens Cause Disease It is important to understand people become ill due to two main reasons: – Improper function of internal organs etc. – Infection caused by pathogen *** With proper preventative care, the incidence of infections caused by pathogens are minimal

3 What are Pathogens Pathogens are microorganisms that invade the human body (other species also). They cause damage to internal organ structure and the proper function of organs There are three types of Pathogens: – Bacteria – Viruses – Prions

4 Bacteria Prokaryotic DNA and Ribosomes only Cell Wall surrounds Plasma Membrane Obtain nutrients from a variety of sources including a “Host’s” cells Shape is that of a Sphere, Rod, or Spiral Most are harmless, and some are beneficial to digestion (think yogurt)

5 Viruses Smaller than Bacteria Their structure consists of RNA/DNA surrounded by a Protein Coat protective layer Are not considered living because they cannot replicate themselves without a “Host” In order to replicate they must insert their genetic material (RNA/DNA) into the DNA of a Host’s cell….. This can spread to billions of the Host’s cells eventually causing death

6 Prions They are ill-formed brain cell proteins that infect and subsequently change the shape of other healthy brain cell proteins Eventually the brain ceases to function due to all the ill-formed proteins “Mad Cow Disease” is a Prion disease that first appeared in cows, then spread to the human population (mainly in Great Britain) Not as common as viral and bacterial infections

7 Pathogen Success There are three factors that determine the evolutionary success of a pathogen: – Ease of Transmission – Mode of Transmission – Virulence

8 Human Body’s Defense Lymphatic System is responsible for three bodily functions: – defend the body against infection and injury – Maintain volume of blood in circulatory system – Transports fats and vitamins from digestive to circulatory system

9 Lymphatic System

10 Lymph Nodes Lymph nodes are small organs in the Lymphatic System, Located in the neck, armpit, and groin. They remove microorganisms, cellular debris, and abnormal cells from the “Lymph” (milky fluid) before returning it to the Circulatory System (aka Cardiovascular System) Recall Lymph comes from the portion of the blood plasma that diffuses out of the capillaries

11 Spleen One of the Spleen’s primary function’s is to fight infection “Red Pulp” in the Spleen contains “Macrophages” that scavenge and destroy microorganisms, old/damaged red blood cells and platelets The Spleen cleanses the blood (Red Pulp) and the Lymph Nodes cleanse the Lymph (Milky Fluid)

12 Human Body’s Defense The Lymphatic System works with other body systems to protect it from Pathogens and cellular damage/changes The human body employs three mechanisms to protect itself from damage and/or death – Physical and Chemical Barriers – Nonspecific Defense Mechanisms – Specific Defense Mechanisms

13 Physical & Chemical Barriers Skin – solid physical barrier that is acidic and constantly replaced Tears – expels foreign contaminants Earwax – prevents contaminants from gaining access to the ear canal Mucus – similar function as that of tears and earwax Vomiting – expels contents from stomach that may have pathogens Urination/Defecation – expels waste material possibly contaminated with pathogens from body

14 Nonspecific Defense Mechanisms If the pathogen is able to breach the external physical and chemical barriers now the body must actively seek out the intruder and destroy it Also, after the pathogen is destroyed, the body must repair the damage done to it by the pathogen Nonspecific Defense Mechanisms respond to all types of health challenges, including pathogen infections

15 Nonspecific Defense Mechanisms Phagocytes – Neutrophils (1 st responders) and Macrophages engulf and digest foreign cells; Eosinophils cluster around large parasites & excreting digestive enzymes to kill them Natural Killer Cells – release chemicals that disintegrate cell membranes of tumor cells and virus-infected cells Inflammatory Response – redness, warmth, swelling, and pain attract Phagocytes & promotes tissue healing Interferons – stimulate the production of proteins that interfere with viral production Fever – mid-grade fevers make environment less welcoming to pathogens

16 Phagocytotic Process

17 Specific Defense Mechanisms Body’s third line of defense is the Immune System is composed of cells, proteins, and the Lymphatic System, all working in concert to detect and eliminate specific pathogens and abnormal body cells (cancer) Activities of the Immune System are called “Immune Response” Immune Response has three important characteristics: 1) recognition 2) memory 3) complete body coverage

18 Immune System and Antigens An Antigen causes an Immune Response Immune System responds by producing 5 types of Antibodies (GAME D) that attack and inactivate the Antigen (protein not found in body) The Immune System can recognize proteins/cells that belong in the body and those that do not MHC proteins are markers that tell the Immune System those cells belong in that body and are not foreign invaders

19 Lymphocytes Lymphocytes play key role in specific defense mechanism 2 types of Lymphocytes: – B lymphocytes B cells mature in bone marrow Responsible for antibody mediated immunity; focus on removing antigens from blood and lymph – T lymphocytes T cells mature in thymus gland Responsible for cell mediated immunity; focus on destroying infected cells

20 B Cells Responsible for antibody-mediated immunity B cells produce antibodies – proteins that bind with and neutralize specific antigens Often referred to as “Immunoglobulins” B cells work best against viruses, bacteria, and foreign molecules that are soluble in blood and lymph B cells mature in bone marrow, then travel via circulatory system to lymph nodes, spleen, and tonsils where they remain inactive until needed

21 B Cells When B cells become active, they reproduce additional cells to fight the antigen Those new cells are called Clones/Plasma Cells Some of the Clone Cells become Memory Cells – long lived cells that “remember” that initial antigen and can reactivate to attack it again if needed Memory Cells store information about the pathogen, and as a result, the immune response is much quicker the second time infection occurs

22 5 Classes of Antibodies

23 T Cells Responsible for cell-mediated immunity T Cells do not produce antibodies Some T Cells directly attack foreign cells that carry antigens Most T Cells release proteins that help coordinate the immune response: actions of T Cells, B Cells, and Macrophages Cell mediated immunity protects the body against parasites, bacteria, viruses, fungi, cancer cells, and cells perceived as foreign (tissue rejection)

24 T Cells T Cells responsible for cell-mediated immunity develop from stem cells in bone marrow T Cells mature in Thymus Gland T Cells react to fragments of antigens, not the whole antigen

25 T Cells Types of T Cells include: – Helper T Cells: direct/enhance activities of many cell types in the Immune System – Cytotoxic T Cells: attack and destroy abnormal cells – Memory T Cells: reactivate upon later exposure to same antigen to form Helper and Cytotoxic T Cells – Suppressor T Cells: may suppress immune response after an antigen has been destroyed

26 Immune System Facts Immunity – body does not suffer the effects of the pathogen as a result of Memory Cells facilitating a Secondary Immune Response that is quick and decisive Immunization – injection of monoclonal antibodies and antibiotics into the body to assist with the immune response Vaccine – an “active immunization” which involves the injection of weakened antigens into the body with the intent of enabling the body to produce Memory Cells to fight the pathogen if it reenters the body in a healthy state (secondary immune response)

27 Immune System Facts Active Immunity develops after a primary immune response which is a response to exposure to a live pathogen and development of symptoms. The cells produce the antibodies themselves. (see vaccine) Passive Immunity is when a person's cells do not produce the antibodies, they receive them by an injection of antibodies or antitoxin.

28 Immune System Facts Monoclonal Antibodies – produced in a lab from cloned descendants of a single hybrid B Cell Antibiotics – drugs that kill or inhibit growth of bacteria; when discovered were derived naturally, now are synthesized in a lab Allergy – inappropriately strong response of the Immune System to an allergen Allergen – any substance that causes an adverse bodily reaction

29 HIV/AIDS History – First documented in January of 1981 by the Center for Disease Control – Thought to have spread to the USA by a gay flight attendant who traveled abroad – Originally called the “Gay Cancer” and/or “Gay Plague” because the initial outbreak was mainly confined to homosexual males

30 HIV/AIDS History continued – Less than a year later the list of at risk individuals expanded to include intravenous drug users, recent Haitian immigrants, and Hemophiliacs regardless of sexual orientation – The virus that causes AIDS was first discovered by a French scientist in 1983 – Circa 1987, Rock Hudson announced he had AIDS and died shortly after

31 HIV/AIDS History continued – In the 1990’s heterosexual celebrities and professional athletes announced they too had acquired HIV: Magic Johnson and Arthur Ashe – The 1990’s saw large amounts of research dedicated to treatment drugs and finding a cure – Currently there are some very effective drugs to treat HIV and keep it from developing into AIDS – Majority of new cases are in Sub-Saharan Africa, and unfortunately those people lack the finances to pay for those drugs to treat HIV

32 HIV/AIDS Three phases of the disease – Acute Phase Virus infects person (host) and replicates ferociously Replication process causes death of lymphocytes in the person’s blood Person may be asymptomatic for several weeks; if person does have symptoms they include fever, chills, aches, swollen lymph nodes, and an itchy rash After many weeks the person’s body reacts to the foreign invader by producing numerous immune cells to fight the virus HIV virus targets Helper T Cells by using that cell’s DNA to replicate its genetic information (RNA) to produce many more viruses

33 HIV/AIDS – Chronic Phase Several months to several years an untreated individual will most likely progress to this phase The continued replication of viruses in the host T Cells leads to the body’s inability to fight off common infections because the Immune System is essentially destroyed Number of HIV viruses increases causing reemergence of symptoms like fatigue, persistent fever, night sweats, persistent cough, and persistent diarrhea These symptoms are a signal that full blown AIDS will develop soon

34 HIV/AIDS – AIDS Lymphocyte count has dropped drastically; viruses have taken over the blood Person is extremely weak and thin due to persistent diarrhea and coughing Person eventually dies due to the presence of another infection People do not die from AIDS, but rather, Acquired Immune Deficiency Syndrome weakens their bodies ability to fight other common infections *** There is currently no cure for HIV/AIDS

35 HIV/AIDS In 2010, people can live for many years with HIV/AIDS due to the presence of drugs that keep the replication process to a minimum If you are poor, and especially if you live in a less developed nation, you may not have access to these powerful drugs AIDS is deadly; the best course of action is to not be exposed to the virus It is worth noting, the method that is 100% effective at preventing exposure to AIDS and other STD’s is Abstinence Update 7/8/2010:,2933,596242,00.html?te st=latestnews,2933,596242,00.html?te st=latestnews

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