What is blood pressure ?
A plastic pipe will compress easily when pressed, but when water is flowing through it, it will not compress as easily, because the water flowing in the pipe, on the walls of the pipe. It applies pressure from the inside which does not allow the walls to press down easily. In the same way we talk about our blood vessels, in this conversation, the blood vessels refer to the large vessels in which the heart pumps blood and the branches of these vessels spread the blood throughout the body, so the blood in these vessels If the blood is flowing, like a pipe and water, it will exert pressure on the walls of these vessels, and we call this pressure "blood pressure". Now your blood pressure mainly depends on two things
1- cardiac output 2-Total peripheral resistance
In very simple language
cardiac output
refers to how much blood the heart is pumping in a given amount of time. Obviously, if the heart pumps more blood, more blood will flow in the vessels and if the blood is more, the pressure exerted by it will also be more.
This
cardiac output
To calculate up to it
Stroke volume and heart rate
can understand the product of ie
Cardiac output= heart rate × stroke volume
Here
stroke volume
means how much blood the heart pumps in one beat. While
heart rate
means how many times the heart beats in a minute.
So this
cardiac output = heart rate × stroke volume
From this equation you must be thinking that if
heart rate
It will increase
cardiac output
will also increase, and to a large extent this is the case. but if
heart rate
It will increase a lot
cardiac output
will decrease, because then the heart will beat at such a speed that it will not be able to collect enough blood to pump it forward. So there will be less blood to pump further, and so on
cardiac output
It can decrease instead of increasing. Another thing that blood pressure depends on is
total peripheral resistance
That is, how much the blood coming from the heart to the vessels is facing obstacles. We press the mouth of the water pipe. The water pressure increases. If the blood vessels become narrow, then the blood pressure will also increase. Now how can the obstruction in the blood vessels be less or more?
The most important role in this is the muscles in our vessels, these muscles receive signals from the brain to contract and expand, their contraction reduces the volume of the vessels, and their expansion The volume increases. In addition to our brain, various hormones as well as many blood pressure control drugs also affect the contraction and expansion of these muscles. Also, we can use a formula to measure the resistance of a blood vessel
R= 8nl / πr⁴
This formula is
Hagen–Poiseuille Law
is made from, which has nothing to do with physics, but our "n" here is actually blood
viscosity
Is. That is how thick the blood is. As someone's body becomes severely dehydrated, their blood can also become thicker (since blood is made up of water). Or the number of cells in the blood due to a cancer etc. is too high due to which the blood has thickened etc
The other thing is the "L" length, how long is the duct we're talking about
The third and most important thing is the "r" that is the diameter of the duct, i.e. how wide or narrow the duct is. And we have already discussed how the muscles in the ducts open or constrict them. In addition, if there is any cholesterol in the duct, etc
plaque
If there is an obstacle, it will also affect its width. So we have understood in a simple way these two things on which blood pressure depends and also many small things affect these two things. As
after load
Iins, of the heart muscles
contractility
Etc. Etc
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