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

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Why do humans need a heart? [on hold]

When I looked up the function of the heart, it says the heart pumps blood throughout the body. But the blood is already throughout the body, as it is recycled back to the heart. It is a chick-egg ...
2
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22 views

Normal ECG/EKG Measurement?

I'm getting started using ECG using a 3 lead system by iWorx. I have place the leads on my two wrists and the ground on my ankle and have recorded some data into the provided LabScribe 3 software ...
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1answer
39 views

Why is heart failure treated as more critical than kidney failure?

The heart pumps the blood to supply tissues and kidney always filters the blood to remove urea,extra water and etc. And all these are vital,so the kidney is as important as heart: and my question is: ...
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46 views

What is the effect of persistent hypothermia on cardiac performance?

I define persistent hypothermia in this thread about the mechanisms of persistent hypothermia. The Graph of Katzung et al. in Pharmacology about Heart Failure: I am thinking which parts here are ...
1
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1answer
104 views

Arm at Heart Level when Measuring Blood Pressure

How come that one's arm has to be at heart level so that the blood pressure can be measured accurately. I've tried researching this question, but most answers to it were just "if the arm is above the ...
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30 views

Do the medical certifications from cardiovascular credentialiting international carry any weight? [closed]

The cardiovascular credentialing international (http://www.cci-online.org/) offers various medical certificates. In the Wikipedia article about sonographers, there is a statement There are two ...
4
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110 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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74 views

What's Incomplete atrioventricular heart block (AV)?

This is unclear for me and I can not understand differences between complete and incomplete atrioventricular heart block.also I want an electrocardiograph of incomplete atrioventricular heart block.
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75 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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1answer
49 views

Biphasic T wave caused by digitalis toxicity

Digitalis is a drug that can be used during coronary insufficiency to increase the strength of cardiac muscle contraction. But when overdosages of digitalis are given, depolarization duration ...
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1answer
65 views

Why is pericardium muscle repolarizated earlier than endocardium? [on hold]

I was reading about heat muscle contraction and I read: The endocardium depolarization happens earlier than pericardium , but pericarduim repolarization happens earlier, therefore the T wave in ...
2
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25 views

Neural correlates of the function of the cardiovascular system?

Are there any known neural correlates of the function of the cardiovascular system? I'm looking for research results that use standard brain imaging techniques (e.g. electroencephalography, ...
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16 views

Atherosclerosis chemical treatment? [on hold]

Is there some theoretical chemical treatment against plaques in atherosclerosis? For example, if we will blow the "roof" and release all content to blood? Or kill all the cells that are in the plaque? ...
5
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1answer
65 views

How can heart disease cause dizziness after eating?

I have been reading several articles explaining dizziness after eating (see here and here), and both articles gloss over something that I found pretty remarkable. Both articles claim that "heart ...
3
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1answer
37 views

Heart Rate being normal when under treatment for the bends

When you surface from diving too quickly; you get "bends" - these are caused by gas bubbles forming in your lungs (especially nitrogen). This causes breathing problems if not treated since the bubbles ...
4
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33 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 ...
2
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1answer
44 views

Speed of effective lymphatic drainage?

Lymphatic drainage occurs from many portions of the body: To venous angle: head axillary lymph nodes hands abdomen legs (I think legs' drainage goes through abdomen) The speed of the lymph ...
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61 views

Why is sarcoma more prevalent and common in right heart?

Ewing's sarcoma or Ewing sarcoma is a malignant small, round, blue cell tumor. It is a rare disease in which cancer cells are found in the bone or in soft tissue. It is more common in right heart than ...
3
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3answers
96 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, ...
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2answers
106 views

What is the name of the condition where no pacemaker cells are active in the heart for a short-time?

Assume that the heart is beating, but no pacemaker cells are working for at least 15 seconds. This would be a very long compensatory pause if extrasystole started it. There may be some low frequent ...
0
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1answer
57 views

What shows how healthy someone is by their heart rate? [closed]

What shows how healthy someone is by their heart rate - how low it is at resting pulse or how low it is during exercise or how large the difference is between the resting rate and rate with load? Any ...
2
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2answers
94 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 ...
2
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1answer
44 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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35 views

Is the molecule nitric oxide responsible for healing blood vessels?

Is the molecule nitric oxide responsible for healing blood vessels? How does nitric oxide heal the blood vessels? I watched a documentary about the healing effects of nitric oxide. In the video I ...
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164 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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3answers
521 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 ...
4
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1answer
175 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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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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1answer
75 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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1answer
64 views

Voltage-gated Potassium channels in the action potential of cardiomyocyte?

There is one type of potassium voltage-gated channels open in Phase 1 too. Some call them early repolarization channels. I am not convinced that the channels are different in different phases: 0, 2, ...
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146 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 ...
4
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1answer
67 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 ...
3
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1answer
102 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 ...
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34 views

What are the mechanisms of disabling extrinsic control of heart?

I started this thread by thinking this question but I developed it further below What is the mechanism maintaining refractory period of pacemakers? My conjecture is that the mechanism is the ...
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1answer
37 views

Can Omega 3 Fatty Acids prevent chest pain in periodic Atrial Fibrillation?

It is debated if omega-3 polyunsaturated fatty acids (N3PUFa) may be effective in preventing AF (atrial fibrillation), meta-analysis here. However, much less has been considered this: Do N3-PUFAs ...
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71 views

What is the nature of action potentials in autonomic nervous system?

My conjecture is that the natures of sympathetic and parasympathetic action potentials are different. My findings propose me that sympathetic action potential is little longer lasting than ...
0
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1answer
38 views

What is the quality rate of intrinsic autoregulation in the heart?

Autoregulation is the maintenance of constant blood flow to an organ in spite of fluctuations in Blood pressure. It involves the relaxation of myocardium and contraction. It is local. I know that ...
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63 views

Are Purkinje Action Potentials Neuronal and Cardiac?

I first thought that action potentials of His-bundle i.e. Purkinje fibers are Cardiac. However, I started to think that this is not enough. I think now that they are neuronal and cardiac. My ...
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How is Calcium regulated in myocardic AP and plateau phase?

The plateau phase is maintained by influx of calcium and outflux of potassium in the second stage: My conjecture is that calcium transforms between two phases ionated phase (free calcium from i/c ...
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1answer
39 views

Spironolactone's role with adrenergic agents in heart failure?

I am studying the treatment plan of adrenergic agents for heart failure. Then, in the group discussion, spironolactone was included. But I cannot understand how it is relevant when considering ...
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32 views

Maximum heart rate increase/decrease while physically active [duplicate]

I'm a computer scientist and implementing a heart-rate monitor for physical exercise. While I try to improve my code, I stumbled over the question how fast the heart rate can change within a given ...
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Public Pacemaker database online?

I am looking for any database about pacemakers with the leads atria A right ventricle VR left ventricle VL I did not find any in Physionet. Is there any anonymous data about different ...
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1answer
58 views

Does physical exercise following lack of sleep increase the risk of sudden cardiac death (SCD)?

Is there any scientific evidence supporting the hypothesis that physical exercise following lack of sleep increases the risk of sudden cardiac death (SCD)? The only relevant research I could find is: ...
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To define the total Resistance of Systemic Blood Circulation

Some systems are in parallel. For instance, the resistance of lungs $R_{\text{lungs}}$. Assume here for simplicity that these parallel systems can be handled linearly. We also consider only Total ...
2
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1answer
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Fast standing and the heart's insufficient accommodation of the increased venous return

Assume you are 45 minutes on the supine position. Furthermore: you stand all of a sudden and fast and without sympaticus activity. The venous return (smooth musculature of vessels) accommodates ...
2
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101 views

Sodium levels and blood pressure

Why does low Na+ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of Na+ cause hypertension or high blood pressure? From what I understand, there are ...
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18 views

To Study Interactions of two molecules in PubChem

Assume you have two substances Diosminum / Hesperidinum. The former strengthens vascular walls. The latter has role in some glycoside biosynthesis. From Biochemistry, I recall that glycodises have ...
2
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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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