Hypertension is characterized by an increase in the amount of pressure on the heart. When treating hypertension, the goal is to reduce the force on the heart, increase quality of life and decrease morbidity. Untreated hypertension can lead to heart attack or stroke.
Contractile Activity
The heart's job is to deliver oxygenated blood to working muscles and deoxygenated blood to the lungs. This occurs through a series of contractions. Blood pressure is measured as the amount of force the heart must work against while preforming its job. Pressure is measured during systole,when the heart is contracting, and diastole, when the heart chambers are filling. A blood pressure reading gives the top number as systole and the bottom number as diastole. According to the book "Cecil Essentials of Medicine" by Thomas Andreoli, anti hypertensive drugs should be given to patients who have chronic blood pressure readings greater than 140/90.
Electrical Activity
The heart begins its contractile activity through spontaneous electrical activity by special cardiac cells, states the book "Anatomy and Physiology" by Kenneth Saladin. The SA node is a group of cells inside the heart that have an unstable membrane, meaning the positive and negative electrons inside of them and surrounding them change. Some ions flow in and others flow out of the cells. When this occurs, the cells become depolarized and begin to send a signal to surrounding cardiac cells to contract.
Calcium and the Heart Beat
According to Saladin, when the SA node begins its spontaneous electrical activity, it is said that it is depolarizing. In other words, its negative ions are decreasing. Negative ions begin to decrease when the fast calcium channels of the SA node are opened. When the SA node reaches a certain voltage, it triggers the calcium channels of the other cardiac cells to open. Small amounts of calcium flow into the cardiac cells which prompts an orchestrated contraction by the cardiac cells. This contraction becomes the hearts beat.
Calcium Channel Blockers
According to the text "Exercise Physiology," calcium channel blockers decrease hypertension by limiting the uptake of calcium. If the calcium uptake of cardiac cells is reduced, the spontaneous contractility of cardiac cells is lessened. Less force is put on the cardiac cells, resulting in a lower blood pressure. Vasodilation is another mechanism of calcium channel blockers. Dilation of the body's vessels also decreases blood pressure.
Side Effects
There are several potential side effects of calcium channel blockers. Heart rate as well as blood pressure is changed with a calcium channel blocker. According to "Exercise Physiology," resting and exercising heart rate and blood pressure decrease if you are on a calcium channel blocker. Exercise capacity might also be increased, especially if you suffer from angina. Fluid retention is another common side effect of calcium channel blocker medications.
References
- "Anatomy and Physiology"; Saladin, Kenneth S.; 2004
- "Exercise Physiology"; Brooks, George A., Fahey, Thomas D., Baldwin, Kenneth M.; 2005
- "Cecil Essentials of Medicine"; Andreoli, Thomas, Carpenter, Charles, Griggs, Robert, Loscalzo, Joseph, eds.; 2004
