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Chapter 8

Chapter 8 HIV and AIDS.docx

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Western University
Psychology 2036A/B
Sarah Khan

Chapter 8 HIV and AIDS Intro: Ryan White - 13 y/o hemophiliac - Contracted HIV through contaminated blood products - Ryan White comprehensive AIDS Resource Emergency (RARE) Act Virus associated with: - Homosexual men - IV drug users - Haitians Only current methods of controlling the spread of the disease is through behavioural change Psychoneuroimmunology - Examines mental health as a cofactor in the progression of disease involving the central nervous system and the immune system Section I: The Science of HIV and AIDS Human Immunodeficiency Virus (HIV) - Virus = toxic or poison - Immunodeficiency = virus attacks and renders useless the immune system Acquired Immunodeficiency Syndrome (AIDS) - Final and most severe stage of the disease - Decreased WBC  opportunistic infections o Pneumocystic carinii pneumonia o Kaposi sarcoma Diagnostic criteria 1. Suppressed immune system 2. WBC < 200/µL of blood Natural Immunity 1st line of defense = skin, saliva, urinary tract, mucus Human skin - 2 layers: o Epidermis  Thin outer layer  Epithelial cells  Keratin (waterproofing protein)  Repels germs and prevents germs from entering the body o Dermis  Connective tissues containing blood vessels, hair follicles, sebaceous glands  Sebaceous glands secrete oily substance that maintains pH and inhibits growth of microorganisms Acquired Immunity - Cells that reside in the blood and other bodily fluids - Learns to recognize and eliminate foreign substances  adaptive process - 4 main characteristics: o Self/nonself process o Antigenic specificity – distinguish between different forms of antigen o Diversity o Immunologic memory B Lymphocytes - B cells/B lymphocytes form in bone marrow - 2 immune functions: o Antibody producing cells  Produce cells that attack specific microorganisms o Memory cells  Encode information that helps them recognize previously encountered and defeated microorganisms T Lymphocytes - T cells/T lymphocytes form in the thymus - 3 types: o T cytotoxis (T C  “killer cells” – kill infected cells o T helper (T H  Helps the system by producing cytokines  Cytokines – agents that produce antibodies to fight invading viruses  Can help direct T Cells or activate B memory cells  WRT to HIV, T cHlls display CD4 glycoproteins on its cells surface - # of CD4 cells is an important measure of the health/functioning of the immune system o T suppressor (T )S  “off switch”  Slows the immune system  Reduce activity of TCand T oHce work is completed Table 8.1 Brief Summary of the Immune System Two Types of Immunity Description Natural (Innate) Immunity Body’s first line of defense against microorganisms includes: skin, saliva, urinary tract, muscles Acquired (Adaptive) Immunity Immunity derived from recognizing and defeating microorganisms that the body has experienced before 4 principal processes: - Self/nonself discrimination Ability of body cells to distinguish between foreign elements and body’s own cells - Antigen Specificity Process of distinguishing among different types of foreign microorganisms and generating a specific immune response to the specific foreign antigen - Diversity Ability of the body to recognize the unique structures of each microorganism - Immunologic memory Ability to recognize a previously presented antigen when it returns, giving the body the ability to response more quickly and effectively against foreign microorganisms Organs and cells Lymphoid organs (tonsils, lymph nodes, thymus, spleen) that produce white blood cells that fight infection - Main cells WBCs or leukocytes that filter microorganisms and help reduce risk of infections - Principal leukocytes Contain neutrophils and macrophages (phagocytic cells) that collect at the site of an injury of the body to release toxins that produce inflammation and fever that contribute to healing - Polymorphonuclear granulocytes Comprise 50-70% of leukocytes but appear to play a minor role in immune process Lymphocytes - B cells Two types that develop and mature in bone marrow - B-memory “remembers” prior invading microorganisms and identifies them when representing themselves; faster recognition aids in the process of destroying foreign antigens - B-antibody forms specific antigens to attack invading microoganisms - T cells Three types born in bone marrow and matured in thymus - T cytotoxis (T C, “killer” cells - destroy cells infected with the virus - T helper (T H help to produce the cytotoxin that destroys invading virus and assists in the maturation of B cells - T suppressor (T )Sslows the immune system by reducing activity of T cClls once invading antigens have been eliminated to prevent damage to the immune system Measuring the Immune System - Measures: o Number of CD4 cells o Cell differentiation o Cell proliferation o Cytotoxicity - Measures can be obtained through blood or saliva - HIV+ patients o CD4 is a measure of the number of T cells H o HIV binds to CD4 cells that serve as the host for the virus o When the virus begins to reproduce – suppressing the immune system, it also destroys the T cells with CD4 molecules - Normal CD4 count = 500-1500 CD4 cells/µL blood - Low CD4 count = 200-499 CD4 cells/µL blood - HIV+ diagnosis = <200 CD4 cells/µL blood o Indicates that the immune system is severely repressed o Seroconversion – individual advances into final stage of illness - Cell differentiation o Measures the degree to which cells divide into the different T cells o Each is needed when combating foreign microorganisms - Cell proliferation o The extent to which the cells multiply o Too little of one type of T cell can diminish the body’s effectiveness in combating viruses - Cytotoxicity o The extent to which the body’s cells are able to kill foreign organisms DNA Viruses vs. Retroviruses DNA viruses - DNA = deoxyribonucleic acid  information needed to construct the cells that comprise our system - DNA housed in the nucleus - DNA virus contains only one strand of DNA - When it DNA virus enters the body, it copes its genetic code onto a viral RNA – the agent that helps the virus reproduce - DNA viruses are easily identifiable by the viral RNA code they display to the immune system Retroviruses - Store their genetic information in RNA - Virus converts its genetic RNA into viral DNA - After recoding as viral DNA, HIV inserts itself into the cell nucleus and copies its genetic material onto the host cell’s DNA - Once embedded, the HIV virus has a host that will help it reproduce when the time is right Section II HIV Prevalence, Human Transmission and Human Behaviour Origins - HIV is thought to be linked to a species of chimpanzees Pan troglodyes troglodyes - Thought HIV was transmitted from chimpanzees to humans as a result of the animal biting a human or from contact with chimpanzee’s HIV-infected blood - HIV is not fatal to chimpanzees – infected primates show no signs of illness or dysfunction from the virus Human-to-Human Transmission - Any activity that results in an exchange of fluids from an HIV-positive person, or that exposes uninfected individuals to contaminated fluids, could result in infection - 3 main routes: o Sexual intercourse  Account for majority of cases  Virus in semen, vaginal fluids and blood o Parenteral (blood-borne) transmission  i.e. blood transfusions  infections from unsanitary needles used by IV drug users o Perinatal (mother-to-child) transmission  Occurs when HIV-positive mother transmits the virus to her child either during birth or possibly through breastfeeding Symptoms of HIV and AIDS - Individuals who carry the virus often report no noticeable symptoms in the early stages of the disease - 15% of HIV+ people are asymptomatic - 25% are unaware during the early stages of the disease that they are infected - For individuals who do experience symptoms, many report flulike ailments, mononucleosis, or frequent rashes that occur 6-9 months after the onset - After the onset of HIV, the virus is dormant – can last 8-10 years - HIV  AIDS (seroconversion) o 1. Succession of opportunistic infect
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