Bioscience 2: Health Breakdown Process Tutorial PDF

Module 9 **Bioscience 2** **The health breakdown process** **Tutorial** **INTRODUCTION** **Please watch the presentation before completing the tutorial activities and read through this entire tutorial and complete the activities BEFORE the session. By understanding the normal structure and func...

Module 9 **Bioscience 2** **The health breakdown process** **Tutorial** **INTRODUCTION** **Please watch the presentation before completing the tutorial activities and read through this entire tutorial and complete the activities BEFORE the session. By understanding the normal structure and function of the immune system you should be able to predict what would happen as the immune system gradually disintegrates.** **LEARNING OUTCOMES** **On completion of this week activities, the student will be able to:** 1. Review the general functions of the immune system and predict effects of dysfunction. 2. Overview the three major groups of diseases affecting the immune response. 3. Influenza: to overview the components of the pathophysiological process. **Resources:** Craft et al (2023). *Understanding pathophysiology* (3rd ed., Australian and New Zealand ed.). Elsevier Australia. **Lee, G., & Bishop, P. (2016). *Microbiology and infection control for health professionals* (6th ed.). Melbourne, Victoria: Pearson Australia.** Marieb, E. N. & Hoehn, K. (2019). *Human anatomy & physiology* (11^th^ Global ed). Pearson Education. **\ ** **1. Overview of immune response problems.** By now you would have learned that one of the functions of the lymphatic system is to protect the body through the **immune response (IR).** This response is produced by activated lymphocytes and is responsible for the detection and destruction of foreign substances that may impair homeostasis\.... and it remembers. It involves the recognition of 'foreign' matter (antigen) and its eradication. **Detect Destroy Eradicate and Remember** Though the role of the immune system is to destroy foreign cells and protect your body there are times when the immune system fails to operate in a normal way, resulting in problems. **Immune response problems** can be summarised as diseases caused by: - **Inadequate response** - **Excessive response** **[Inadequate response] (immune deficiency)** There are two types of **immunodeficiency disorders**, *primary* or *secondary*. Both of these disorders will render a person susceptible to infections/diseases normally prevented by an intact immune system. See p 220 of Lee & Bishop (2016). - **Primary,** *or born with*, is because of defective B lymphocytes, T lymphocytes or both. Associated with gene mutation that is sporadic, not inherited. - **Secondary** -- *or acquired*. This can develop during the life span of a person where the immune response is suppressed. A patient with an immunodeficiency disorder is said to be \_\_immunosuppressed/ immunocompromised\_\_\_ *This flow diagram might be helpful as a summary* - ***Primary & Secondary result in susceptibility to reoccurring infections*** - ***Allergies & autoimmunity lead to mild to severe inflammation and tissue damage*** **[Excessive response] (immune overactivity)** An excessively intense immune response to an antigen that it has previously encountered, produces inflammation and causes tissue damage and disease is called a **hypersensitivity disorder** ('allergy'). There are various types of hypersensitivity, and the consequences can vary from mild itching to potentially fatal anaphylaxis. The antigens ('allergens') may be inhaled; ingested; injected or simply by direct skin contact. - **Inappropriate response** Complete the following table **Autoimmune disease** **Affected organ or tissue** **Brief description or consequences** ------------------------------- ----------------------------------- -------------------------------------------------------------------------------------- **Multiple Sclerosis (MS)** **Rheumatoid Arthritis (RA)** **Antibodies, connective tissue** **Precipitation of immune complexes in joints, resulting in inflammation of joints** **Hashimoto's disease** **Crohn's disease** **Vitiligo** Is there a cure for autoimmune diseases? - **Hypersensitivity** -- already addressed in module 7. Please go back to this module to review the 2 stages of an allergic reaction (initial and subsequent exposure). There is a growing population of people who have allergies. For those people it is normal for their immune system to have an excessive response to a certain substance(s) they come in contact with (allergen). Can you think of anyone with an allergy? What are they allergic to? What immunoglobulin is associated with an allergic reaction? Ig E **2. HIV infection and AIDS** As mentioned at the start of this tutorial, an inadequate immune response can be caused by a number of factors, however all resulting in the inability to fight infections. HIV/AIDS is an infection well known for causing millions of deaths by destroying the helper T cells and depressing the immune system, leading to an inability to fight infections. **Complete the following sentences using provided words**. *CD4^+^, destroyed, failure, immune, latent, prevent, retrovirus, syndrome, AIDS, infection, progressive* Acquired immune deficiency **\_\_\_\_\_syndrome\_\_\_\_\_\_\_\_\_** (AIDS) is caused by the human immunodeficiency virus (HIV), a **\_\_\_\_\_\_\_retrovirus\_\_\_\_\_\_** unknown until the early 1980's, but since then it has spread around the world to infect millions of people. The primary target of HIV is the **immune** system itself, specifically targeting T-helper ( CD4**\_\_\_\_\_**) lymphocyte, which is gradually **\_destroyed\_\_\_\_\_\_\_\_\_\_\_\_\_.** Viral replication actively continues following the initial HIV **\_\_infection\_\_\_\_\_\_\_\_\_,** and the rate of T-helper (**\_\_CD4\_\_\_\_\_)** lymphocyte destruction is **\_\_\_\_progressive\_\_\_\_\_\_\_.** Clinically, HIV infection may appear **\_\_\_latent\_\_\_\_\_\_\_\_** for years during this period of ongoing immune system destruction. During this time, enough of the immune system remains intact to provide immune surveillance and **\_\_\_\_\_prevent\_\_\_\_\_\_** most infections. Eventually, when a significant number of CD4+ lymphocytes have been destroyed and when production of new CD4+ cells cannot match their destruction, then **\_\_\_failure\_\_\_\_\_\_\_\_** of the immune system leads to the appearance of clinical **\_\_\_\_AIDS\_\_\_\_\_\_\_.** *Note: AIDS does not occur until an individual is at late-stage HIV. You do not automatically have AIDS if you are infected by HIV. They are often referred to as the same thing by many.* **Pathophysiology of influenza- in-class activity** Influenza is a viral infection impacting millions of people across the world each year. According to WHO, it is responsible for approximately 650 000 deaths annually. Affecting all age groups, people most at risk are: - children under 5 years of age - the elderly - those with chronic health conditions (eg chronic cardiac or pulmonary diseases) - those with immunosuppressive conditions (eg receiving chemotherapy) The following resources may be useful in researching the following questions: Lee & Bishop (2016) p432 a. *How would you **define** influenza?* *Seasonal influenza virus infections cause worldwide epidemics annually, resulting in millions of infections with significant morbidity, mortality and economic burden* b. *What is the **cause/aetiology**?* *The causative agents are the influenza viruses (orthomyxoviruses),* *Three types- A, B, C* *A -- animals, birds, humans* *B- humans* *C- mild respiratory illness* c. *Explain the **pathogenesis** (development of the disease leading to the diseased state) of influenza* *The virus enters the respiratory tract via droplets and attaches to respiratory epithelial cells via the H spikes.* *One to three days after infection, symptoms such as fever, chills, malaise and muscle pain develop, due mainly to cytokines liberated from damaged cells and infiltrating leucocytes. As the virus spreads, symptoms of runny nose, sore throat and dry cough may occur. Subclinical or mild infections resembling a cold are common. Recovery usually occurs within 1-- 3 weeks, although the infection can be severe enough to develop into bronchitis or pneumonia.Viral shedding begins before the appearance of symptoms, and usually persists for about a week. Mortality is highest in the elderly and the debilitated, and is usually due to secondary bacterial pneumonia or exacerbation of chronic cardiac or respiratory disease.* d. *What were his **clinical features**?* *One to three days after infection, symptoms such as fever, chills, malaise and muscle pain develop, due mainly to cytokines liberated from damaged cells and infiltrating leucocytes. As the virus spreads, symptoms of runny nose, sore throat and dry cough may occur. Subclinical or mild infections resembling a cold are common.* e. *What is the typical **course** of influenza?* f. *What is typical **prognosis**?* g. *How is influenza **diagnosed**?* *A specific diagnosis can be made by reverse transcription polymerase chain reaction (RT-PCR) or viral culture of nasopharyngeal or throat secretions. Rapid tests that detect viral antigen in respiratory samples have been developed and are becoming more widely used. They have high specificity (few false positives), but only moderate sensitivity (false negatives are common). However, a laboratory diagnosis is impractical and unnecessary for individual cases, but is more important when investigating epidemics or pandemics caused by a new virus strain.* h. *What pharmacological **treatment** can be given for the infection?* Rest, fluids and analgesics form the basis of treatment, and a generally healthy person will usually recover within a week. Zanamivir (Relenza ® ) and oseltamivir (Tamiflu ® ) are specific antiviral drugs that can be used to treat influenza caused by either influenza A or B viruses. They act by inhibiting viral neuraminidase, thus blocking the release of newly formed viruses from infected cells. However, they should be given early in the illness, preferably within 48 hours of onset of symptoms.They are generally only recommended if the symptoms are severe or if the patient is at high risk of complications (e.g. young children, the elderly and pregnant women). There is some concern regarding the development of resistance to oseltamivir in some influenza viruses. Antibiotics are required if secondary bacterial infection occurs. i. *How can an influenza infection be **prevented**?* *Antiviral drugs are not substitutes for immunisation, which is the primary way to control influenza. When given before the epidemic season arrives, influenza virus vaccine offers protection against those strains covered by it. The vaccines are made from inactivated viruses and are directed against several strains of the virus. The composition of annual vaccines in Australia is decided by the Australian Influenza Vaccine Committee, and is based on the anticipated spread of active influenza A and B viruses according to worldwide surveillance and on recommendations of the WHO. The annual vaccine does not necessarily protect against strains not included. The WHO recommends vaccination for high-risk individuals such as the elderly and debilitated (e.g.* *residents of nursing homes and chronic care facilities), and people with chronic cardiopulmonary disease. Vaccination is also strongly recommended for pregnant women and healthcare workers. Because of antigenic drift and the short duration of protection afforded by the vaccine, annual immunisation is necessary. Efforts are currently aimed at the development of a universal influenza vaccine, which would protect against all flu virus strains, and hence would not require annual renewal.*