Although they sound alike and look like Irish twins on paper, Hypertension and Hypotension are complete opposites of each other. Hypertension is when you have dangerously high blood pressure, whilst hypotension, which is just as dangerous, happens when your blood pressure is too low.

The raising and lowering of blood pressure is a job that is performed by your body’s automatic nervous system, which uses its vast network of nerves, receptors and hormones to constantly control the rate of blood flow.  This automatic balancing act between the sympathetic nerve network, which raises blood pressure and the parasympathetic nerve network, which lowers it, allow us to be physically active without drastically changing our blood pressure.

Causes of hypotension

Reduced blood volume is one of the most common causes of low blood pressure. This is called hypovolemia and can have many different causes. Lacking enough blood in your system can be caused by such things like severe internal or external bleeding, diarrhea, vomiting, and dehydration. Pretty much anything that reduces the amount of fluids in your body can cause reduced blood volume, including using too many diuretics.

Decreased cardiac output, or heart failure, is another cause of low blood pressure.  Your blood pumping blood slowly, or not at all will cause, a drop of blood pressure and lead to cardiogenic shock. Heart arrhythmias, which are irregular heartbeats, can cause this response to a lack of blood pressure, as can certain medications, such as Beta blockers, which are taken for high blood pressure.  Even certain “lifestyle” medications cause this, which is why it is important that you let your doctor know about everything you take both over and under the counter.

Excessive vasodilation, which mean that your arteries are not properly constricting, is yet another reason for low pressure. A brain injury or abnormality in the automatic nervous system can cause this as could certain medical conditions like infections that go untreated, or acidosis, which is a increase in blood acidity. Certain medications, like Nitrate preparations  and certain anesthetics can also cause vasodilatation.

Forms of hypotension

The most common form of low blood pressure is called orthostatic hypotension, or postural hypotension. As the second name implies, it occurs when there is a rapid change of body position, usually from a seated position to standing. It is usually temporary. This is the most commonly caused by low blood volume. Taking blood pressure measurements while the person is seated, lying down and standing can confirm this.

The second form of hypotension is called neurocardiogenic syncope and commonly results in fainting. A sudden drop in blood pressure while standing characterizes it.

The other form of hypotension is rather rare and is called postprandial hypotension. This form of hypotension occurs about 30 minutes to an hour after eating. It occurs shortly after eating because it is associated with digestion and the intestines need for increased blood flow. It is caused by the body being unable to compensate for this. Some doctors believe this is caused by a faulty or aged autonomic nervous system.

Symptoms of Hypotension

• Feeling Light headed (especially when sitting up)
• Extreme thirst
• Feelings of fatigue
• Shallow Breath
• Nausea
• Fainting Spells

If you have one or more of these symptoms, you should get your blood pressure checked. Also, even if you do not experience the above symptoms, you should still be put on alert If your blood pressure reading happen to come out too low during a checkup.

How does hypotension affect the body?

The Brain: low blood pressure causes your brain to get less oxygen causing dizziness and fainting.  Lack of blood to the brain also can cause confusion and adversely affect the nervous system. 
The Gastrointestinal System: also suffers from lack of blood flow leading to the feeling of nausea.
The Heart: Since low blood pressure means that your blood is not flowing correctly, strain is put on your heart as it works harder to pump blood to all of your vital organs.
Kidneys: lack of blood flow can also keep the kidneys from properly eliminating all the toxins from your body.