High & Low Blood Pressure: Causes & Treatment

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  • 0:03 High and Low Blood Pressure
  • 0:32 Hypertension: Causes…
  • 5:19 Hypotension: Causes…
  • 6:53 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

You've certainly come across the two main terms this lesson will discuss when it comes to blood pressure. But can you name the multitude of reasons why they occur physiologically? That's what you'll find out about in this lesson!

High and Low Blood Pressure

High blood pressure is something we have all heard of as a term. This is likely because every other health ad on TV seems to be one aimed at treating high blood pressure. While high blood pressure itself is a big problem that many times doesn't have an identifiable cause, in other instances a reason for its existence in the body is present. These causes, and the causes for low blood pressure, are what this lesson will be about.

Hypertension: Causes and Treatment

High blood pressure - a systolic pressure of 140 mmHg or more or a diastolic pressure of 90 mmHg or more - is formally known as hypertension. If you didn't know, a reading of 120/80 mmHg is optimal. Systolic blood pressure, the top number, refers to the pressure at the time when your heart contracts, whereas diastolic blood pressure, the bottom number, refers to the time at which your heart relaxes and fills back up with blood. Since the contraction of the heart forces a lot of blood out into circulation, it makes sense that systolic blood pressure is higher than diastolic blood pressure. At any rate, let's examine the potential causes for hypertension and why, physiologically speaking, they cause this result.

Kidney disease is one potential cause of increased blood pressure. The kidneys help to excrete water out of the body by using the sodium ion. Sodium is that stuff found in table salt your doctor warned you about. If the kidneys are sick and they don't excrete enough sodium and water, this causes lots of fluid to remain in the blood vessels, and this increases blood pressure. It's sort of like sticking a finger into an open hose, preventing the outflow of water. This will raise the pressure inside the hose.

Problems in the arteries of the body can cause increased blood pressure. If stenosis, the narrowing of an important artery, occurs, then blood begins to back up in the arterial circulation, leading to hypertension again. Again, go back to our poor, abused hose. If you clamp down on a portion of the hose, the pressure will rise upstream from that area.

Cancer can also lead to hypertension. One notable and dangerous form of cancer, called a pheochromocytoma, releases hormones, such as norepinephrine, which cause the arteries to constrict. If the arteries constrict, this raises the blood pressure. You know that if you were to take an inflated balloon and squeeze it with both hands, the pressure would rise inside the balloon - so much so that it may actually pop. Well, the signals released by this tumor cause the blood vessels to squeeze down on themselves, raising the blood pressure within them.

Other things that can cause hypertension include endocrine disease. For instance, hyperaldosteronism is a condition where excess aldosterone is produced. This leads to increased sodium and water retention by the kidneys, raising the blood pressure once again. In essence, the body tries to 'hold it in' - the fluid, that is - like you may have to 'hold it in' on a long car ride.

Another cause of hypertension is hyperthyroidism, which is another endocrine disease that produces too much thyroid hormone. This hormone stimulates the heart to increase cardiac output. If the volume of blood the heart pumps out increases, then blood pressure rises. In this case, it's like turning the faucet to full speed, increasing the amount of water flowing out. Overall, chronic high blood pressure anywhere in the body causes direct damage to, scarring of, and weakening of blood vessels, with subsequent further repercussions as a result of that in each specific location and organ system thereafter.

Anyways, you can clearly appreciate the multitude of things ranging from kidney dysfunction to anatomical problems to endocrine gland disease that can cause hypertension. While treating the underlying cause, if one is found, of hypertension is important in ensuring longevity in a person, we also need to treat the hypertension itself, especially if we don't find a cause for it. Options for treatment include, but aren't limited to:

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