What is Blood Pressure?

Blood pressure is vital for life. Whenever a patient tells me they have blood pressure, my usual response is ‘Great!’ Like most things in life, it’s important to have just the right amount of blood pressure. If your blood pressure goes too low, you can collapse and if you have high blood pressure your arteries lose their elasticity and become hardened and damaged, leading to complications.

Why you need blood pressure

You need a certain pressure within your circulation to keep blood flowing around your body, just as a hose pipe needs pressure for water to travel through. Within the circulation, this pressure comes from the pumping action of your heart as it pushes blood through your arteries, and depends on:

  • the volume of fluid inside your circulation
  • how hard your heart is pumping at any particular time
  • the elasticity or resistance of your arteries.

If your arteries are elastic and can dilate easily to even out surges, for example, your blood pressure will tend to stay within healthy limits.

How blood pressure varies throughout the day and night

Your blood pressure naturally varies throughout the day and night, going up and down in response to your emotions and level of activity. When you have high blood pressure, or hypertension, however, your blood pressure remains high all the time, even at rest and while you are asleep.

When blood is forced through the circulation under a consistently high pressure, it damages your artery linings. This hastens hardening and furring up of the arteries so they become less elastic and less responsive to signals telling them to dilate. This hardening, in turn, increases your blood pressure even further, and if you don’t do anything to halt its progression, the health of your circulation will gradually deteriorate.

In the long-term, untreated high blood pressure damages both small and large arteries throughout your body and can lead to failing eyesight, difficulty thinking straight and kidney failure.

High blood pressure also increases your risk of experiencing heart failure, heart pain (angina), a full-blown heart attack or stroke.

Although this all sounds rather frightening, the good news is that early diagnosis and treatment of a high blood pressure can bring it down to within normal levels and keep you healthy.

You can have high blood pressure without knowing

If you have not had your blood pressure checked within the last year or two, you’re not alone. Two out of five people with high blood pressure remain blissfully unaware they are walking around with a ‘silent killer’. And that includes many people who are already on treatment for their high blood pressure.

Even when your blood pressure is high enough to damage your circulation and internal organs you usually notice few, if any, symptoms. As a doctor I’ve seen the devastating consequences of untreated hypertension.

One of the main problems is that most people have no obvious red-flag symptoms, even when their blood pressure is dangerously high. That’s why it’s vital to know your blood pressure numbers. If you haven’t had your BP checked in the last year, book an appointment with your family doctor now – especially if high blood pressure runs in your family.

Ask me a question about blood pressure

I’ve set up this website to provide all the information, tips and advice you need to keep your blood pressure under control.

Just a few relatively simple lifestyle changes could save your life.

If you have any questions about blood pressure, how it’s treated, or what you can do to help improve your readings, ask via the comments box below and I’ll get back to you as soon as I can.

Please note, I can only give general advice. For individual advice, or if you have any persistent symptoms or worries, please consult your own doctor.

If you have a diagnosed health condition, or are taking any prescribed medicines or over-the-counter remedies, always check with your doctor or pharmacist before taking any food supplements or herbal medicines.

If your blood pressure is borderline or raised, self-monitoring is key to maintaining good control.

Click here for advice on choosing a blood pressure monitor to use at home.

See my recommended upper arm blood pressure monitors.

Image credit: production_perig/shutterstock

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12 thoughts on “What is Blood Pressure?

  • Sylvie

    Hi there

    I wanted to share my blood pressure story.

    When I was a teenager I had high blood pressure. When I was at school in grade 8 in gym class and I had to run around the gym my legs would be like rubber they would just give out from under me, and I would fall to the ground. I would also have a lot of nose bleeds. After a lot of tests they found out I had high blood pressure. At 16 when I went for my physical for grade 9 something was really wrong, so they sent me to sick kids in Toronto. I remember being tied down to the bed with blood pressure cuffs on both arms and both legs. I could feel my heart beat into my head. It was beating really fast. My doctors went into the hall to speak to my mother about my case. I over heard them say that I was like a ticking time bomb. My blood pressure was 260/125 and my pulse was 120. They discovered that the arteries of my kidneys was blocked and I had to get it removed right away. So I went to surgery they removed one of my kidneys. The operation was a success. I was on blood pressure medications from when I was 16 yrs old until I was 30 yrs. At 30 yrs old I decided, that I didn’t need these blood pressure pills anymore. I had to prove to my doctor that I was taking care of myself naturally that I didn’t need those pills. For one month my doctor had me take my blood pressure every day and write it down. After a month I went back to the doctors and showed him my blood pressure log book, my pressure was staying low average 110/75 which is pretty good compared to when I was younger. I’m in perfect health living with one kidney. I do yoga, meditation, exercise, I eat organic fruits and veggies, I had gained a lot of weight in the last few years after my father passed away. I was eating my emotions, but I finally put myself back in gear LOL. and lost a lot of weight again. I’ve got an other 15 pounds to lose before I reach my goal weight but I feel great.

    • DrSarahBrewer Post author

      Thanks Sylvie, for sharing your story to underline how serious high blood pressure can be, but how diet, lifestyle and a positive approach can help to overcome it. Medical treatment is lifesaving, and not everyone will be able to stop their meds but losing excess weight will definitely help as you’ve found.

  • Kelsey

    Hi Dr. Sarah,
    This is a very comprehensive and educational website on blood pressure. It interests me because just a month ago my brother-in-law was found fainted at a bus stop in the wee morning hour after his night shift. He was rushed to ICU and suspected due to a stroke. In the scan, it was found that some blood vessels have burst and the blood flowed into the left portion of the brain area. He was under observation for 2 days to see if the condition stabilised otherwise a surgery may be needed. The doctor claimed the collapsed was due to high blood pressure.

    From our knowledge, he was a smoker but not under any medication. I believed he went for his company’s yearly medical checkup and didn’t recall him mentioned about hypertension. As you have pointed out, improper dieting could be another factor. He usually eats out and often sleeps late due to his shift duties. All these contributed to the sudden attack at was least expected.

    While in ICU on the fifth day, his heart beat was very low at 36bpm throughout the day and doctor advised that a pacemaker to be fitted to help him to recover faster. Since he was already 60 years old, family members agreed to the operation so that he can eventually go for rehabilitation.

    Thanks for your website which I believe many will find it useful too. I will visit this page regularly to find out more and learn how to take care of my health, particular the blood pressure and my heart.

    Kelsey Lim

    • DrSarahBrewer

      High blood pressure is an insidious condition as it creeps up without causing much in the way of symptoms until calamity strikes. Sometimes a stroke can occur for other reasons so your brother-in-law may not necessarily have had untreated hypertension, but this is a wake-up call for other family members to get a general check-up if they’ve not had their blood pressure checked in the last year. I do hope your brother-in-law makes a good recovery. I’m glad you found my site useful. I intend to add more pages .on complications such as stroke.

  • Mara

    Interesting article. A friend of mine who I consider relatively young had a heart attack last year, and had no pre-warning beforehand. Thankfully he is OK now, but it’s a huge scare and he is paying a lot closer attention to his overall heart health now. It’s great you’ve emphasized the need for regular blood pressure check ups to keep on top of things. What are your thoughts on energy drinks? I have heard that some people who drink a lot of these can be affected with a racing pulse and other symptoms – especially if consumed on top of other caffeine products. I find it concerning that they are so readily available but there don’t seem to be any warnings that go with them.

  • Lauren Kinghorn

    Thanks for that brilliant explanation of blood pressure and especially what it depends on. I know this sounds like a crazy question, but I was wondering whether it’s possible to have raised blood pressure in humid climates? I used to find when visiting Durban that I’d always feel unwell. I never tested my blood pressure, but it felt to me what I would imagine high blood pressure feels like. Weird question I know… any research to support my theory?

  • Vicky

    This explains blood pressure very well thank you. My mother has high blood pressure. Fortunately I’ve always had good numbers but haven’t checked them for a while. I wasn’t sure if there were any symptoms to look for but you made that clear here that there really are non.

    My question is am I high risk to get high blood pressure since my mother has it? Or are there no relevance to family history and blood pressure?

    Thank you,

    • DrSarahBrewer Post author

      Hi Vicky, High blood pressure can run in families if you inherit genes that make salt processing less efficient via the kidneys, or a tendency towards less reactive arteries, for example. It’s a good heads up to keep an eye on your BP as you get older – I’d check it every year as it can slowly creep up. Thanks.