Longest to Shortest:
<span>across the diameter of the galactic halo - 200,000 light years
</span><span>across the diameter of the galactic disk - 100,000 light years
</span><span>from the sun to the center of the galaxy - 26,000 light years
</span><span>across the diameter of the central buldge - 20,000 light years
</span><span>through the disk from top to bottom - 1,000 light years.</span>
Answer:
The fewer number of T cells a person has, the more chances to be affected by an opportunistic infection. When the number of T cells reaches 200 cells/µl, the person is at risk of being infected by other infections.
Explanation:
The whole immune system of a person who is infected with HIV infection seems to be severely affected. When the person is not treated or the disease is in a very advanced stage, the depletion of the T- cells turns to be very sharped, especially CD4+ T cells. At this point, the immune system can not resist the attack of other microorganisms. The <em>lower is the number of CD4+ T Cells, the higher possibility the person has to be attacked by opportunistic infections. </em>
Classically, it has been suggested that opportunistic infections appear after the CD4 + T lymphocytes reach very low levels, such as 200 cells/µl. The number of circulating T cells can be used as an indicator and a measure of global "immune competence", and the previously mentioned amount of CD4 + T cells is an accepted universal reference used to predict the risk of having one of these opportunistic infections.
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the answer is d. break down matter from dead plants and animals
