Learn to control hypertension now!
You have probably heard about high blood pressure, its risks to your health and the diets to control it. But, do you know what blood pressure actually is?
Blood pressure is the force exerted by the blood against the walls of the arteries at its passage through it.
In some cases, this pressure can increase or decrease and these variations usually have consequences on health.
Do you want to know the causes of these alterations and how do they affect your day to day life? Would you like to know how to restrain hypertension? If you do not know the answers to these questions or you are interested in knowing more, stay with us and keep reading!
What are the causes of a high or low blood pressure?
Blood pressure relies on two basic factors: the cardiac output and the peripheral vascular resistance.
Cardiac output is the volume or amount of blood expelled by our heart’s ventricle in one minute. It is calculated multiplying the stroke volume by the heart rate, as it is shown in the following equation:
CO (Cardiac Output) = Stroke Volume x Heart Rate
Stroke volume is the amount of blood that our heart is able to expel in one contraction, also known as systole. The average stroke volume is somewhere between 60 and 80 millimetres.
On its behalf, the heart rate refers to the number of times the heart beats in one minute.
Thus, a person with a stroke volume of 60ml and a heart rate of 70 beats per minute, will have a cardiac output of 4200ml. In other words, an individual of such a cardiac output moves up to 4,2 litres of blood in one minute.
Additionally, the peripheral vascular resistance is the way the arteries resist to the passage of blood through them. It will depend on the diameter or calibre of the artery in that precise moment.
Vasoconstriction, that is the decrease of the artery’s calibre, raises the peripherical vascular resistance. Likewise, this resistance is also affected by the maintenance of our arteries’ contraction due to the activity of the sympathetic nervous system.
Therefore, an increase in the cardiac output and/or the peripheral vascular resistance is directly related to an increase in blood pressure, while, if these values decrease, blood pressure will decrease as well.
How can the cardiac output and the peripherical vascular resistance be altered?
Some activities, daily practices, accidents or the consumption of certain substances can affect these parameters without us noticing it.
Altering the cardiac output
We can modify the cardiac output altering the blood volume, meaning the total amount of blood in our blood vessels, or changing the heart rate.
The more blood running through our blood vessels, the more the cardiac output will be. In adult men, the average blood volume is 5 or 6 litres, while the average blood volume in women is somewhere between 4 and 5 litres.
The blood volume can be altered by the loss of liquids due to dehydration, bleedings or the consumption of diuretic medicines that raise the amount of times urination is needed.
What is more, the heart ratecan also be altered, resulting again in a change in blood pressure.
In fact, the heart beat is an autonomous process started in the sinus node, also known as the heart’s pacemaker. On the one hand, the sympathetic nervous system regulates this process, raising the heart rate in extreme situations. On the other hand, the parasympathetic nervous system counters the previous effect, making the heart rate decrease when the danger is gone.
Furthermore, some internal and external factors also directly affect the heart rate.
For instance, as the age increases, the heart rate tends to decrease. Additionally, the age also establishes the highest heart rate that can be reached without suffering health problems, being lower as the age increases. In fact, if you want to know your highest heart rate, you have to subtract your age from 220.
The body temperature also influences the heart rate, especially in feverish episodes. When there is a fever, the body temperature rises and, as a consequence, the heart rate also increases. In the same way, when there is high ambient temperature, the amount of times the heart beats in a minute also increases.
Another external factor that affects the heart rate is the altitude, since, as it increases, the oxygen levels decrease, so the heart has to compensate this deficiency by pumping blood faster so as the oxygen can properly distribute throughout the entire body.
Likewise, the more the body area is, the more oxygen is needed. Thus, unless the heart is well-adapted, a higher heart rate will be needed.
Finally, anxiety and stress also accelerate the heart rate. This is due to the secretion of adrenalin and noradrenalin by our organism in order to get ready in case it needs to escape from a danger. This response was very useful to our ancestors, since they had to constantly face risky situations. However, in modern society, those risks do not exist anymore, so, if the secretion of these hormones lasts too long, it can end up being harmful to the health.
Why does the peripherical vascular resistance change?
As we said before, this resistance depends on the calibre and the flexibility of the blood vessels.
The calibre of the vessels can be affected by some mechanisms that exert a vasoconstrictor or vasodilator effect. Some medicines or a change in the ambient temperature can trigger these effects.
Therefore, an increase in the ambient temperature causes our vessels to expand, while a decrease of the temperature makes them to contract. This is why our blood pressure usually falls on summer and rises on winter.
The flexibility of the blood vessels also affects the blood pressure. The more the flexibility is, the less the peripheral vascular resistance, and this effect will make the blood pressure to decrease. The age, sedentarism or the diet are some of the elements that can affect the arteries’ flexibility.
In Clinica Excelan we are always looking after your health. If you need medical assistance, do not hesitate to make contact with us by a phone call, Whatsapp or email.
If you want to know how to correctly measure your blood pressure, which are the normal values and how can you put into practice what we have explained you with some advises to keep your blood pressure under control, we expect you in our next post.