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Results demonstrated that the majority of CIVD occurred during the warming condition when the thermometrically-estimated mean body temperature T b was at its highest.
A thermoregulatory pattern was identified whereby CIVD occurred soon after T b increased past a threshold approximately These findings were independent of extremity temperature since CIVD episodes occurred at a large range of finger temperatures 7. Some of the more common examples are outlined below.
When the environment becomes too warm, the thermoreceptors trigger vasodilation. This directs blood flow toward the skin, where excess body heat can escape. People with obesity are more likely to experience changes in vascular reactivity. This may occur when the blood vessels do not constrict and dilate as they should. Specifically, people with obesity have blood vessels that are more resistant to vasodilation.
This increases the risk of hypertension and associated cardiovascular diseases, such as heart attack and stroke. Blood vessels contain receptors called baroreceptors. These constantly monitor blood pressure and trigger vasoconstriction or vasodilation as needed.
As a person ages, their baroreceptors become less sensitive. This can reduce their ability to maintain steady blood pressure levels. Blood vessels also become stiffer and less elastic with age. This makes them less able to constrict and dilate as needed. The air at high altitudes contains less available oxygen.
A person at high altitude will therefore experience vasodilation as their body attempts to maintain oxygen supply to its cells and tissues. Although vasodilation decreases blood pressure in major blood vessels, it can increase blood pressure in smaller blood vessels called capillaries.
This is because capillaries do not dilate in response to increased blood flow. Increased blood pressure within the capillaries of the brain can cause fluid to leak into surrounding brain tissue. This results in localized swelling, or edema. Medical professionals refer to this condition as high-altitude cerebral edema HACE.
People at high altitudes may also experience vasoconstriction within the lungs. This can cause a buildup of fluid within the lungs, which medical professionals refer to as high-altitude pulmonary edema HAPE.
In some cases, a doctor may induce vasodilation as a treatment for certain conditions. In other cases, vasodilation may be what requires treatment. Vasodilators are medications that cause the blood vessels to widen. Doctors may use these drugs to reduce blood pressure and ease any strain on the heart muscle.
There are two types of vasodilator: drugs that work directly on the smooth muscle, such as that in the blood vessels and heart, and drugs that stimulate the nervous system to trigger vasodilation.
The type of vasodilator a person receives will depend on the condition they have that needs treatment. Vasodilation is an important mechanism. However, it can sometimes be problematic for people who experience hypotension or chronic inflammation. People with either of these conditions may require medications called vasoconstrictors. These drugs cause the blood vessels to narrow.
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