10 votes
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How can heart disease cause dizziness after eating?

Dizziness after eating, which can lead to falls and passing out, is called postprandial hypotension, and as the heart is indeed responsible for responding to hypotension by increasing it's rate - ...
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9 votes
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Is a one ventricle heart feasible?

Alternative Heart Morphologies Amphibians and some reptiles have a three-chambered heart, with 2 atria and a single ventricle. There are still separate circulatory pathways for the lungs and the rest ...
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8 votes
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What creates the feeling of 'excess' blood pressure to an area of the body?

Arterial Baroreceptors felling the pressure. Arterial blood pressure is normally regulated within a narrow range, with a mean arterial pressure typically ranging from 85 to 100 mmHg in adults. It is ...
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7 votes
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Arm at Heart Level when Measuring Blood Pressure

This page (and many others) explain the idea rather well. This is more of a physics than a biology question, but the fundamental concepts are the same. In fact, contrary to what you wrote in the ...
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7 votes
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Why is it always Sodium that we talk of in blood pressure?

The key is in fluid compartments and osmotic activity. For the purposes of this discussion, let us say that there are two fluid compartments the ExtraCellular Fluid (ECF) and IntraCellular Fluid (ICF)....
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6 votes
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Why do people perceive blood pressure as the force that moves the blood forwards (see details)?

In the vascular system, pressure is what moves blood forwards, at least in an analogous manner to voltage...just like voltage, pressure itself doesn't move things, but a pressure gradient does. You ...
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5 votes

Osmotic Pressure in Capillaries

Fluid movements across capillary wall is determined by 2 main factors. Hydrostatic Pressure (Blood Pressure) - tends to push fluid out of the blood vessel Osmotic Pressure - Tends to pull fluid back ...
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5 votes
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Why does high blood pressure not damage the body during exercise?

Actually it can. See https://clinicalhypertension.biomedcentral.com/articles/10.1186/s40885-016-0052-y for instance: Deleterious effects of HRE [hypertensive response to exercise] on structure and ...
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5 votes
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How does pressure measured by sphygmomanometer translate directly to blood pressure?

Korotkoff sounds! The blood pressure measurement process is fairly cool, and goes like this. Inflate the cuff to well over plausible blood pressures (250mmHg or so). Slowly deflate the cuff while ...
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5 votes

How do physics notions of fluid dynamics relate to pressure gradients in circulation?

As far as we know so far, biology isn't able to break any laws of physics. However, biology isn't passive: biological systems react to changing environments to maintain some level of homeostasis. ...
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How to understand the biophysics and math behind a 0.2 second delay between the pulse in my arm and my ankle?

So it turns out that your estimate is not bad, by simple velocity calculation, I get it to be a little over 50% out (see below), but as you say, there is some error in your measurement. However, it ...
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4 votes

How does the mechanism which controls blood pressure in the brain work?

Blood pressure is sensed in blood vessels by baroreceptors. Baroreceptors are stretch-sensitive nerve fibers located primarily in the aortic arch and carotid sinuses. The baroreceptors send afferent ...
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3 votes
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Consequences of abnormal blood pressure unrelated to cardiac output?

Blood pressure, as you noted, is just a means to an end: the flow of blood through tissues. The trouble is, many of the body's regulatory systems use blood pressure (rather than flow) as an index of ...
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3 votes

What could an increase in systolic blood pressure and decrease in diastolic mean?

First, a couple of considerations Heart rate (HR) is lower when seating, and even lower when lying. I assume that participants were seated when the first measure was taken. Cardiac output is not ...
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3 votes

High Blood Pressure - Na or NaCl?

High blood pressure is caused by an excessive amount of fluid circulating in the blood vessels, or an excessively small mean blood vessel diameter. The later is more associated with stress situations ...
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Why does weight loss lower blood pressure?

Weight gain increases blood pressure, the reason for this process is due to the effect of hormone called Leptin. Leptin is made by fat and circulates in the bloodstream to reach the brain, where it ...
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Why can blood vessel contraction be described as a second order system?

Many systems have this property. The plot you are looking at is the plot of the transfer function for blood vessel diameter vs time. A trick in mathematics or engineering is to understand a system is ...
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  • 2,167
3 votes

How does sodium ion increase blood pressure?

Sodium acts on the juxtaglomerular cells of the kidney, which are then activated to produce and secrete renin. Renin hydrolyses angiotensinogen into angiotensin I. Next angiotensin converting enzyme (...
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  • 2,462
3 votes

Blood pressure measurement

The sound in question is called the Korotkoff sound: If the pressure is dropped to a level equal to that of the patient's systolic blood pressure, the first Korotkoff sound will be heard. As ...
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Difference between pulse and blood pressure

The blood pressure is the fluid's movement "strength" in the arteries (or "artères", please edit my post with the correct english word) Blood pressure is a measurement of the strength of flow ...
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  • 161
3 votes

What is the normal blood water content

The human blood contains about 45% of erythrocytes and 54.3% of plasma by volume. The plasma contains about 92% water, while the erythrocytes, about 64% by weight. The blood is slightly less than 80% ...
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2 votes

Why do changes in preload not cause changes in end systolic pressure?

Preload is defined as the volume of blood that stretches the ventricle at the end of diastole. Therefore, when preload is increased, the end diastolic volume is increased. In simpler terms, there is ...
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2 votes
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Specialist evaluation for people aged under 40 years with stage 1 hypertension

Alongside full guidance released by NICE they also produce treatment pathways which give further advice - here is the treatment pathway for hypertension. You've listed most of the investigations that ...
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2 votes

Thrombus and Embolii

Yes, treatment of thrombus can cause embolism. Hypertension favors hemorrhagic complications. Thrombolytics: Yes, they can cause paradoxical embolism, although it is a rare complication [1]. The ...
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2 votes

People say the cardiac cycle depends on blood pressure? How so?

There are two levels to take your question at. The first is simpler but I'm not sure if it is what you are looking for: If you imagine the heart and all the blood vessels in your body as a closed ...
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2 votes
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How are limits determined for systotic and diastotic blood pressure?

120/80 are not upper limits on blood pressure - many people have blood pressures far in excess of those numbers. Instead, these are numbers beyond which studies have shown connections to negative ...
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2 votes
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Cardiac cycle and atrial contraction

While blood is flowing into the ventricle, it can never be at a higher pressure than where blood is flowing from: if it was, the flow would be going in the other direction. Flow is always from higher ...
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2 votes

Why does the formula for blood velocity hold true?

The trick here is that 1 mL = 1 cm3 (or cc). So if you divide cm3/s by cm2 the result will be in cm/s. What that means is that the blood volume has three dimensions - if you picture the vessel as a ...
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2 votes

How do physics notions of fluid dynamics relate to pressure gradients in circulation?

First, you are misapplying Bernoulli's law. At each point, Bernoulli's law says that $$\text{constant}=P+\frac{\rho v^2}{2}$$ But remember, that constant is not constant in time for unsteady flows; ...
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1 vote
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Why does the formula for blood velocity hold true?

In the capillaries the A must be extremely low For a single capillary yes, the area is small. However, these statements are not referring to a single capillary! They are referring to the entire ...
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