The continent can be broken into four major landform regions: the Coastal Plains, the Eastern Highlands, the Central Lowlands and the Western Plateau. These landform regions have been created by movements in the Earth's crust, river erosion and changes in climate and sea level.
Causes of Low HGB and Low HCT. Figuring out hematocrit levels in the blood is done through Mean Corpuscular Volume or MCV and Red Cell Distribution Width or RDW. These tests determine whether someone is suffering from low Hgb and/or low HCT levels in their blood and can help doctors determine a cause. 1.Anemia is the direct result of a low red blood cell count.iguring out hematocrit levels in the blood is done through Mean Corpuscular Volume or MCV and Red Cell Distribution Width or RDW. These tests determine whether someone is suffering from low Hgb and/or low HCT levels in their blood and can help doctors determine a cause.
1 A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson's disease; tricyclic antidepressants; erectile dysfunction drugs, particularly in combination with nitroglycerine; narcotics and alcohol. Postural (orthostatic) hypotension This occurs for some people when standing from a sitting or prone position. 2  Their blood pressure drops rapidly, causing dizziness, lightheadedness, blurred vision and/or even fainting. 3  Causes can include dehydration, prolonged bed rest, diabetes, heart problems and excessive heat.