Answer:
Rivers usually begin in upland areas, when rain falls on high ground and begins to flow downhill. They always flow downhill because of gravity. They then flow across the land - meandering - or going around objects such as hills or large rocks.
Explanation:
Hope this helps!
Answer: d) lightheadedness or unconscious episodes.
Explanation:
There are several ways the body responds to stress but one method used by psychologists to measure this response is Hans Selye's general adaptation syndrome. This occurs in 3 stages:
1. The alarm reaction. This occurs when the stressor is first presented resulting in the RELEASE OF HORMONES from the adrenal gland into the blood stream. The hormone in turn cause sympathetic nervous system activation and increase energy levels, INCREASE RESPIRATION, increase muscle tension, reduce sensitivity to pain, slow down the digestive system, and cause a RISE IN BLOOD PRESSURE.
2. The stage of resistance- this occurs till the stress is removed.
3. The stage of exhaustion
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.
