Solve Haemodynamics Confusion: Peripheral Resistance, Sympathetic Stimulation

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In summary, constriction of blood vessels leads to an increase in arterial pressure and resistance. However, cardiac output can still increase due to an increase in heart rate. Moreover, constriction of vessels can also lead to an increase in venous return through pressure changes, which triggers an increase in heart rate to maintain stable blood flow.
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Rahat34
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Im not able to get this concept of haemodynamics. Constriction of blood vessels increases arterial pressure but it also increases resistance, so how does cardiac output increase? How can constriction of vessels increase venous return? It incteaes systolic filling pressure but resistance also increases.?
Can anyone relate all this to sympathetic stimulation.? I am really confused.

Thabk you.
 
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I know nothing of biology, but from the verbal mathematical model that states:

[tex]R \propto \frac{1}{r^4}[/tex]

where:
R = resistance
r = radius of vessels

R is bound to increase as r decreases (which is what happens when vessels constrict, their radius decreases)

Plug in some numbers in r and you will see it matches the mathematical model.
Rahat34 said:
Im not able to get this concept of haemodynamics. Constriction of blood vessels increases arterial pressure but it also increases resistance, so how does cardiac output increase?
From here (about half a page down) cardiac output is defined as:
[tex]CO = HR x SV[/tex]

where:
CO = Cardiac output
HR = Heart rate
SV = Stroke volume

The stroke volume may not increase with increased resistance, but the heart rate will increase to try to keep everything working smoothly. Therefore, CO increases as well. (Of course, that inference is assuming HR increases way more than what SV decreases. Otherwise they just balance each other out.)
Rahat34 said:
How can constriction of vessels increase venous return?
Pressure increases due to the lower pipe diameters causes some of the blood to flow back (and other forward, depending on where the constriction took place and what we define as "back" and "forth"). That at the same time triggers an increase in the heart rate to prevent this from destabilizing the flow which answers the previous question as well.
 
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1. What is peripheral resistance?

Peripheral resistance refers to the resistance of blood flow in the peripheral blood vessels, such as the arteries and veins in the arms and legs. It is determined by factors such as vessel diameter, vessel elasticity, and blood viscosity.

2. How does sympathetic stimulation affect haemodynamics?

Sympathetic stimulation, also known as the fight or flight response, causes an increase in heart rate and vasoconstriction (narrowing) of blood vessels. This leads to an increase in blood pressure and peripheral resistance, as the body prepares to respond to a perceived threat or stressor.

3. What causes confusion in haemodynamics?

There can be several causes of confusion in haemodynamics, including changes in blood pressure, heart rate, and peripheral resistance. Other factors such as medication, illness, or dehydration can also contribute to confusion in haemodynamics.

4. How can haemodynamics confusion be solved?

To solve haemodynamics confusion, it is important to identify and address the underlying cause. This may include adjusting medication, addressing any underlying health conditions, or making lifestyle changes to improve overall cardiovascular health. Consulting with a healthcare professional is recommended for proper diagnosis and treatment.

5. What are the consequences of prolonged haemodynamics confusion?

Prolonged haemodynamics confusion can have serious consequences on overall health. It can lead to issues such as high blood pressure, heart disease, and organ damage. It can also increase the risk of stroke, heart attack, and other cardiovascular events. Therefore, it is important to monitor and address any confusion in haemodynamics to prevent these potential consequences.

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