23. What are the components and functions of the immune system? What two main types of immunity do you know?
The immune system is a system that protects human’s body against disease-causing microorganisms and cancer cells. It consists of lymphatic vessels, lymph nodes, lymph fluid and lymphocytes. There are two main types of immunity. Humoral immunity involves substances found in the extracellular fluids, such as antibodies and proteins. Cell-mediated immunity doesn’t involve antibodies, but rather involves the activation of lymphocytes.
24. What is HIV infection? Speak on two main strains of HIV. What does HIV affect in the human body?
It is infection in which certain immune cells are destroyed by HIV, it results in loss of the body’s ability to protect itself against infectious diseases.
HIV has 2 main strains HIV-1 and HIV-2.
HIV is a lentivirus (a subgroup of retrovirus) that causes the acquired immunodeficiency syndrome (AIDS)
The HIV itself doesn’t kill the patient. It destroys the immune system, leaving the patient susceptible to other diseases.
HIV infects a specific type of white blood cells (T-cells). The virus attacks T-cells that have a protein known as CD4 on the outer membrane. This kind of cell is essential in triggering the immune response to infection or other foreign materials. The HIV invades CD4 cells and inserts its own genetic material into them. Thus, it uses the cell’s resources to create more copies of the virus and eventually kills the CD4 cell. After CD4 cells are destroyed, the body is no longer able to fight off infections or kill cancer cells.
25. What are the ways of HIV transmission?
The HIV is transmitted through body fluids such as blood, breast milk, semen, vaginal fluids, sharing needles for IV drugs. The virus can be transmitted through organ or tissue transplants. An infected mother may pass the virus on to her unborn child through placenta. Susceptibility to HIV infection increases if there is damage in or mucous membranes, which allows the virus enter the bloodstream.
HIV can’t be transmitted through simple physical contact.
26. What does the term “opportunistic disease” mean? Name and speak on some of them.
Opportunistic disease is a disease that occurs more often in people with weakened immune system. AIDS patients may have the following opportunistic diseases:
Kaposi’s sarcoma – that is a type of skin cancer;
Thrush – is a fungal infection caused by the Candida albicans;
Pneumocystic pneumonia – is a fungal infection of the lungs caused by Pneumocystis carinii;
Tuberculosis;
Gastrointestinal infection;
Cytomegalovirus – which affects the retina and causes blindness;
Cervical cancer etc.
27. Describe the course and possible treatment options of the disease.
Various drugs have been developed to fight the HIV infection. They are AZT (zidovudine), DDI (didanosine). These drugs try to disrupt key chemical reactions in HIV’s metabolic cycle, including those controlling its reproduction. But the virus mutates rapidly, and the drugs lose their effectiveness.
However, there are new antiviral drugs that are used to treat HIV infection. They are protease inhibitor, entry inhibitor, reverse transcriptase inhibitor, and integrase inhibitor. These classes of drugs prevent creation, assembly, and spread of new viruses. A doctor may prescribe a combination of these drug classes known as highly active antiretroviral therapy (HAART).
Treatment for AIDS consists of treatment for HIV infection and treatment for opportunistic infections. It includes medications specific for each type of infection.
28. How to reduce the risk of being infected with AIDS?
To prevent the HIV infection I-V needles should be safely disposed and shouldn’t be shared, blood for transfusion should be tested before use, people should practice safe sex, and a pregnant woman with AIDS should take zidovudine to reduce the chances of passing HIV to the foetus.