Introduction / Context:
Acquired Immunodeficiency Syndrome, commonly known as AIDS, is a serious condition caused by the Human Immunodeficiency Virus. A key feature of this disease is a progressive weakening of the immune system. This question checks whether you know which specific cells in the blood are targeted and destroyed by the virus, leading to immune deficiency. Understanding this helps in grasping why AIDS patients are vulnerable to opportunistic infections.
Given Data / Assumptions:
- The disease mentioned is AIDS, caused by a virus.
- The options include haemoglobin, red blood cells, T cells in blood, and grey cells in brain.
- We assume basic knowledge of the components of blood and immune system.
Concept / Approach:
HIV primarily infects CD4 positive T lymphocytes, also called helper T cells. These cells coordinate immune responses by signaling other immune cells. When HIV infects and destroys these T cells, the immune system becomes compromised. Haemoglobin is a protein in red blood cells, not a cell itself. Red blood cells carry oxygen and are not the main target of HIV. Grey cells in the brain refer to neurons in brain grey matter, which may be affected indirectly but are not the primary target in blood. Thus the correct approach is to identify T cells as the central target of the AIDS virus.
Step-by-Step Solution:
Step 1: Recall that AIDS is caused by the Human Immunodeficiency Virus, which attacks the immune system.
Step 2: Identify helper T cells, also known as CD4 T lymphocytes, as key coordinators of immune responses.
Step 3: Understand that HIV binds to CD4 receptors and enters these T cells, using them to replicate and eventually destroying them.
Step 4: Recognize that loss of T cells leads to a gradual collapse of immune defenses, characteristic of AIDS.
Step 5: Note that haemoglobin is simply the oxygen carrying pigment in red blood cells, not a separate cell type.
Step 6: Recall that red blood cells carry oxygen but are not primarily infected by HIV.
Step 7: Realize that grey cells in brain refer to neurons, and although HIV can cause neurological complications, the main diagnostic feature in blood is the depletion of T cells.
Step 8: Conclude that T cells in blood are the primary targets of the AIDS virus.
Verification / Alternative check:
Medical guidelines for diagnosing and monitoring HIV infection emphasize measuring CD4 T cell counts. A falling CD4 count is a key marker of disease progression towards AIDS. This clinical fact directly supports the idea that T cells are targeted. No standard reference associates haemoglobin or red blood cell counts as the main early markers of HIV destruction in the immune system. Neurological complications of HIV occur later and are secondary to systemic infection. Therefore, focusing on T cells in blood is the correct and verified interpretation.
Why Other Options Are Wrong:
Haemoglobin: This is an iron containing protein in red blood cells and is not a cell type; HIV does not primarily destroy haemoglobin molecules.
Red blood cells: Although overall health can affect red cell counts, HIV infection is defined by immune system failure rather than direct destruction of red blood cells.
Grey cells in brain: These are neurons, and while dementia can occur in late stages, they are not the main cellular target used to define AIDS in blood tests.
Common Pitfalls:
Students sometimes confuse the general idea of blood disease with red blood cell involvement, leading them to pick red blood cells or haemoglobin. Another mistake is to overlook the role of the immune system in AIDS and focus only on the word virus. Remembering the term CD4 T cell count, which doctors check in HIV patients, is a strong clue that T cells are central to the disease. Keeping immune cells and blood cells conceptually separate helps avoid such errors.
Final Answer:
The virus that causes AIDS primarily attacks and reduces the number of
T cells in blood.
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