The study of the physiology and pathology of the cardiovascular system, especially the heart.

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Extremely rare occurence of Heart cancer?

The occurrence of Heart cancer (similar, but not the same as Rhabdomyosarcoma) is extremely rare, about 1 per year according to MayoClinic. The reason for this rarity is explained to be the ...
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319 views

How is the blood volume of a living organism measured without killing it?

How is the blood-volume of an organism measured without killing it? NOTE: The blood-volume of an organism is defined as the total volume of blood present inside that organism.
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732 views

Is there any relationship between heartbeat rate and life span of an animal?

Is there any relationship between heartbeat rate and life span of an animal? Do they belong to a cause-and-effect relationship or are they both caused by some phenomenons or a common cause?
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493 views

What does irregular heartbeat mean in simple language?

I bought a blood pressure monitor (A&D UA-851) which has the option to measure irregular heartbeat. I do understand what 'irregular' means, but why do irregular heartbeats happen and what are ...
11
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152 views

Why don't we see turbulence in the aorta even in normal situations?

I read about the Windkessel effect. Then I read about pulse pressure waves getting reflected from the periphery. If the pulse pressure wave is reflected during diastole and at the same time blood is ...
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4k views

How does sodium in one's diet affect blood pressure?

Due to high blood pressure, my doctor has recommended I go on a low-sodium diet. So, that got me wondering what it is about sodium that drives this recommendation? What does sodium do to a body ...
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852 views

Why do people say that trans fatty acids are bad for your health?

I've heard from several sources that trans FAs are bad for you and their consumption will lead to cardiac problems, and that they are indigestible. But I also learned from biochemistry that they are ...
9
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419 views

Does arterial blood always flow away from the heart?

Is there a negative net flow of blood in human arteries at any point of the cardiac cycle? I realise that blood flow can be turbulent, e.g. in the aorta or around stenotic arteries, but then the ...
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446 views

Why is blood pressure higher the more distal an artery is?

Why is blood pressure generally higher in more distal arteries?
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80 views

How can we measure cardiac output?

I could find a way which could find it by body oxygen consumption and there is another way to measure it by injecting drugs — measuring cardiac output by the so-called “indicator dilution method,” a ...
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Why does the heart use lipids (and not glucose)?

Fetal hearts use glucose as their primary metabolic substrate. Adult hearts use free fatty acids, which are less efficient (require more $O_2$ to synthesize the same amount of ATP); however, during ...
7
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69 views

Can humans live without their right atrium?

The right atrium is one of four chambers (two atria and two ventricles) in the hearts of mammals (including humans) and archosaurs (which include birds and crocodilians). It receives deoxygenated ...
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629 views

What effect does ambient temperature have on the cardiovascular system?

I am sorry if this is not appropriate for this site, but I think it fits so I am asking it here: I went for a run yesterday, and it was about -8⁰C. I was wearing a couple pairs of shorts, a t-shirt ...
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89 views

Does the Heart Require Gold?

I distinctly remember an episode of NOVA from the early 1980’s that concerned itself with gold. One of the points that was made was that there are trace amounts of gold in the human body, ...
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80 views

Why can't we defibrillate the heart within 1 minute after ventricular fibrillation by electroshock?

We mostly can defibrillate the heart before 1 min of ventricular fibrillation by electroshock.Then we often can't do defibrillate it with electroshock. What's the reason and What's the best way to ...
5
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3answers
534 views

When to measure resting heart rate and blood pressure for following day-to-day trend?

I'd like monitor my resting heart rate and blood pressure to see how they are affected by regular cardiovascular training and other events in life. When should I take the measurements in order to ...
5
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66 views

How does vasoconstriction/vasodilation change blood pressure?

Background: I am coming at this question from an electrical engineering background, and I feel like I am missing certain assumptions that are going into the statement found in my physiology textbook, ...
5
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1answer
51 views

Calling for Free Online Data for Paediatric ECG?

I need free online data about heart murmurs to study these: heart murmur frequency , S2 heart sound frequency and its split, murmur timing, and duration, murmur intensity, S3 sound presence and ...
5
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1answer
169 views

Is a raised baseline between T and QRS normal in any ECG lead?

Here are excerpts from an unknown ECG lead. I find it weird that the "baseline" changes after the T wave and doesn't return until after the following QRS complex. Is that normal/expected for any lead? ...
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36 views

Why do the size of the phase 1 notch vary among cardiac cells?

The size of the phase 1 notch varies among cardiac cells. It is prominent in myocytes in the epicardial and midmyocardial regions of the left ventricular wall and in ventricular Purkinje fibers. ...
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406 views

How do insects such as crickets circulate blood through their antennae?

Some insects, like the crickets pictured below, have such slender antennae it seems no blood could fit. How do they get blood through their antennae?
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33 views

What’s the reason for isovolumic contraction and isovolumic relaxation?

During cardiac cycle, there are two periods in which the heart volume doesn’t change, but there is a change in tension/pressure. It takes about 0.25-0.35 second to achieve this change. I searched in ...
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3answers
156 views

How does strength of a pulse related to EKG(ECG)?

There are variabilities in the heart rate as well as strength of heartbeats. I want to know if one can predict which heartbeat will be strong or weak based on the corresponding EKG/ECG signal. I am ...
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64 views

Does transplanted heart have full sympaticus without medication?

I am reading this and this where I am considering this sentence [N]o baseline parasympathetic innervation [in transplanted heart]. Does this sentence imply that the heart work then in full ...
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114 views

Why does max heart rate decrease with age?

I have heard that max heart rate declines steadily with age, and can be approximated by the equation Max Rate = 220 - Age. What is the physiological reason for this decline, and how is it ...
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250 views

How quickly can the human heart rate rise and fall?

How quickly can the human heart rate rise and lower? For example lets say a human heart rate is rested and is at 60BPM and that person is suddenly scared to trigger their fight or flight reaction. ...
4
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64 views

What would life expectancy be in the western world in the absence of Ischemic heart disease?

In 2012, the leading cause of death was Ischemic Heart Disease. In 1st world countries, what is the life expectancy for people who do not die of Ischemic Heart Disease? I'm interested in the USA, ...
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206 views

intravenous (IV) in the tail vein of an anaesthetized mouse

I trained myself to do intravenous injection on live mice. However, on anaesthetized mice you don't see the flux of your product showing that your injection was successful. In the same way, on live ...
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66 views

Can you measure ECG from a single location?

I want to make a DIY bracelet to measure my ECG. All I need is the interbeat interval. Can I design a bracelet on one arm only, with two electrodes slightly spaced from one another, and figure out ...
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78 views

Is this ventricular tachycardia?

I am investigating the public data of this. Its specification ...
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99 views

What percentage of human capillaries are located in the skin?

As in the subject line, what percentage of capillaries in a human (expressed in terms of total length, I suppose) are located in the skin, as opposed to internal organs? Google scholar has not turned ...
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31 views

How to measure Na/K channel activation at the membrane level?

Assume that there are two different signals occurring on the ECG - during depolarization and repolarization in the standard ECG. I was advised not to use the standard ECG in measuring the exact ...
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31 views

Effect of Aging on SA node's sympathetic fibers

I am trying to understand the effect of aging on the sympathetic fibers of SA node. I know that aging shifts the vagal curve to left in frequency due to aging. However, I am interested if aging has ...
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122 views

Why shouldn't you defibrillate a flat line (asystole)?

In most popular medical dramas, when a patient is in cardiac arrest and has a flatline the doctors use a defibrillator to 'shock their heart into rhythm'. I know that actually, the proper protocol is ...
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618 views

What is the ratio of breathing rate to heart rate?

Breathing rate and heart rate are directly connected. This is because the heart is connected to the lungs via the pulmonary artery. I first thought that breathing rate would be half of the heart rate ...
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204 views

Amount of neurons in the heart

Finding numbers for the amount of neurons in the brain is quite easy. Finding them for other human organs is harder. How many neurons are there in the human heart?
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104 views

Are ectopic beats considered sinus rhythm for pNN50 purposes?

One quantification of the heart rate variability of an ECG is pNNx, i.e. the proportion of consecutive NN distances that differ by at least 50 ms. When a premature beat occurs, the preceding and ...
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1answer
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fibroblast cells and fibers

I am interested in fibroblast cells in human arteries. Here are the things that I am not clear at the moment and I could not find any answer from the literature: What are the dimensions of these ...
3
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1answer
91 views

Elevated position effect on recovery times from upper respiratory infections at rest?

In nursing school, they advice for people with upper respiratory infections to be in a slightly elevated position at the head region when sleeping. My intuition of the reason is that the lymphatic ...
3
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61 views

What is the correct medical procedure(s) for taking a resting heart rate?

Note: I thought the Biology stack exchange would suit this question better than the Fitness stack exchange. Please let me know in the comments if this is not suitable here. I am interested in ...
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ECG of heart transplant patients

I am studying ECGs of heart transplant patients. The difficult thing is that there is so little available data publicly. I must apply for data in my universities. It would be also great if ...
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31 views

Why does a pacemaker have a negative pulse? [closed]

Why is the first phase of the pulse from a pacemaker cathodic?
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129 views

What is atrial fibrillation? [closed]

I am wondering exactly what a-fib is (causes and symptoms). I would really appreciate having a sample of an EKG with it (because in my limited research, I have found it nearly impossible to find just ...
2
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2answers
108 views

To get Standard ECG from PhysioNet?

I am trying to get standard ECG by using PhysioNet's ATM with parameters but I get It should be something like How can you get complete standard 12-lead ECG out of Physionet database?
2
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1answer
454 views

What is the surface area of the human heart?

I heard that the human heart had a surface area of 1000 square feet, and I thought that that cannot be true. So what is the surface area of the human heart and what are the different ways it can be ...
2
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2answers
807 views

Why there is a very high drop in pressure from arteries to arterioles?

Laplace law explains why the pressure is the same in aorta and arteries (100). I am thinking why there is so big drop in pressure when going from arteries to arterioles (40-60). Why there is a great ...
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2answers
89 views

Breakdown current for human body

If I am not mistaken, during exposure to electricity sources it is the magnitude of the current and not the voltage that kills the human body. If so, what is the order of magnitude of current that ...
2
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1answer
39 views

What are the benefits of statins in terms of prolonging life?

Recently the UK government suggested that all adults over the age of 50, without exception, would benefit from taking statins. I have an elderly female relative who may, or may not have had a minor ...
2
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1answer
2k views

Function of the Auricle in heart

What is the function of the auricles (conical appendages through the atria) present in the heart? Do they have any other function than increasing the volume of blood the heart can hold?
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Why does the arch of aorta coils?

My study materials use the word vesselcompression chamber of aorta to emphasize aorta's elastic property. The arch of the aorta only coils, not its straight part. I think the reason why the arch ...