With hypertension, or high blood pressure, commonly recognized as a health problem that can lead to serious complications, many people assume that lower is better when it comes to blood pressure. This, however, is not so. Adequate blood pressure ensures that the heart is pumping the blood with sufficient force to distribute it to all areas of the body--even those that require blood to travel against the flow of gravity to reach. There are several symptoms of hypotension, or low blood pressure. These symptoms may occur suddenly if blood pressure drops.
Dizziness
One of the first and most easily recognized signs of a drop in blood pressure is dizziness. Anyone who experiences a blood pressure drop may notice a feeling of lightheadedness or disorientation, but the sensation is familiar to almost everyone through the common experience of orthostatic hypotension, meaning postural blood pressure drop. When a person suddenly stands from a seated or reclining position, the heart fails to respond to the change in position as rapidly as the postural change occurs, meaning that there are a few moments during which blood pressure is too low for adequate blood distribution to the brain. This is because, notes Dr. Gary Thibodeau in his book "Anatomy and Physiology," the brain is above the heart, and the heart has to combat gravity to deliver blood to the brain.
Vision Changes
While chronic low blood pressure can cause changes in visual acuity, notes MayoClinic.com, sudden drops in blood pressure may dramatically affect the ability to see. As blood pressure drops and blood fails to reach distant tissues--particularly tissues of the brain--the cells in those tissues become oxygen-deprived and fail to function normally. The light-sensing cells of the eyes are particularly sensitive to oxygen deprivation, and it's quite common for individuals with sudden drops in blood pressure to notice that their visual field becomes blurry or dark. Generally, the effect begins at the periphery of the field and progresses toward the center, with longer-lasting drops in pressure leading to complete but temporary blackening of vision.
Fight or Flight Response
As blood pressure drops, cells begin sending distress signals. The brain cells, in particular, notify the rest of the body very quickly if they are oxygen deprived. This initiates what is commonly called the "fight or flight" response, notes Dr. Lauralee Sherwood in her book "Human Anatomy." The fight or flight response is the body's way of dealing with emergency situations, such as sudden drops in blood pressure, and includes increased strength and rate of heart contractions. As the heart beats faster and harder, blood pressure generally rises.
References
- "Anatomy and Physiology"; Gary Thibodeau, Ph.D.; 2007
- MayoClinic.com: Hypotension
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
