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

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Why are vegetations in Infective endocarditis common on the atrial side?

Robbin's Pathology says that vegetations of IE are more common on the atrial side in AV valves. In Liebmann Sack's Endocarditis, which is a sterile (non bacterial) type of endocarditis, the underside ...
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158 views

Explanation of ECG in MI using an electrostatic model

I found a paper presenting an electrostatic model to explain the ECG recorded in various leads. This model essentially calls for considering the depolarization wavefront to be the major contributing ...
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53 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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95 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 ...
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337 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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105 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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670 views

Why is the blood pressure in the superior vena cava during inhalation less than during the exhalation? [closed]

For further investigation into the progress of the blood pressure, we will measure a patient's blood pressure in the superior vena cava measured during inhalation and during an exhalation. His heart ...
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86 views

What's Incomplete atrioventricular heart block (AV)? [closed]

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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148 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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212 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?
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162 views

Does our heart stop when we sneeze?

Is it fact or myth that our heart stops beating for moments when we sneeze? If it is fact, what drives the heart to start beating again?
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1k views

Valves in the heart

I am confused regarding the presence of valves in the superior vena cava. The superior vena cava does not possess valves unlike inferior vena cava, which possesses Eustachian Valve. Then where are ...
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860 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 ...
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7k 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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146 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 ...
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73 views

Is blood pressure in the aorta and brachial artery the same or different?

Does the blood pressure at the root of aorta equal the blood pressure in the brachial artery? I've heard it does, but it doesn't quite seem to make sense as I'd think the blood pressure would be ...
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145 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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56 views

To determine no beating cardiomyocytes from ECG or video recording

I am trying to find data and some method by which I can see and say that there are some cardiomyocytes not working. I have reviewed many arrythmia data where I think I can see much cardiomyocetes ...
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6k 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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152 views

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 ...
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3k views

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 ...
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176 views

Why is elevated homocysteine considered a risk factor for angina?

Elevated homocysteine levels are listed among risk factors for angina. How is homocysteine related to the heart? Or the coronary arteries? How do these relationships make it a risk factor for angina? ...
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51 views

Can stress echocardiography show coronary blood flow difference before and after exercise?

Stress echocardiography means a pair of cardiac ultrasound imaging examinations, before and after exercise. I assume that coronary blood flow is increased after exercise. Is cardiac ultrasound ...
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1k views

Is it possible that the recipient of a heart transplant would display some of the donor's personality traits, as if the heart has memories?

I've read somewhere that after a person has a heart transplant, it is possible that his/her attitude, action or behavior would change slightly or significantly, as though he/she possesses some aspects ...
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78 views

How are isovolumetric contraction and afterload related in the cardiac cycle?

In the cardiac cycle isovolumetric contraction occurs and causes a pressure gradient. The "afterload" is the pressure exerted on the ventricle from the artery. Is the afterload the cause of ...
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34 views

How are cardiac cells stimulated by an action potential?

Why, and how, does the action potential of one cell in the heart stimulate an action potential in the next cell? I'm interested in an answer with citation.
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45 views

Physiology of tricuspid and bicuspid(mitral) valves

The tricuspid and bicuspid valves are atrioventricular valves. Both are valves that prevent backflow of blood pumped from the atria to the ventricles. However, the former has 3 "flaps" while the ...
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1k views

How long do the periods of systole and diastole last?

The background to this is i'm doing some work using ECGs for an animation of the heart and i'm having trouble defining the end points of these periods, particularly diastole. Currently, the only ...
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101 views

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 ...
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152 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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15k views

What is the effect of extra-cellular potassium concentration on heart rate and conduction velocity?

If the extracellular potassium concentration surrounding a myocyte increases, then the potassium gradient accross the cell membrane decreases, and therefore the resting membrane potential will become ...
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5k views

How do inward rectifier potassium channels work in the heart?

Apparently in cardiomyocytes, there is an inward rectifying potassium channel that operates during phase 4 of the cardiomyocyte action potential. I have heard that despite this potassium channel ...
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170 views

Do nerve cells cause action potential in cardiac muscle?

I think the answer is no, but I am not 100% sure. If it was yes, then the dendrite of the nerve cell should each time receive a stimulus causing Na+ channels to open, when the contraction happen. ...
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47 views

Why is there a structural difference between the bicuspid and tricuspid valve?

There are three cusps in the tricuspid valve and only two in the bicuspid valve? Why is there such a structural difference? Does it have anything to do with that there is oxygenated blood on the left ...
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87 views

Why do earthworms have 4 hearts?

I was reading about earthworms and came to know that they have 4 hearts. Why is there a need for a 4 heart system? What advantages would it have over a 1 heart circulatory system except for pumping ...
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75 views

What is the insight of Frank Starling law of the heart?

The Frank Starling law appears to be a trivial observation: stroke volume is directly related to the end diastolic volume In everyday language, as more blood fills the heart, the heart pumps more ...
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36 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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57 views

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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55 views

Could below zero decibel environment cause arrhythmia? [closed]

While this topic has virtually no real life application and has never been examined due to obvious reasons, it is quite intriguing to me. I've read a lot of speculations and claims about the world's ...
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41 views

If a receptor is inhibited throughout embryogenesis, could there be observable phenotypic differences in the adult?

So I read a journal article entitled "Maternal hypoxia and caffeine exposure depress fetal CV function during primary organogenesis" (Momoi, et al., 2012) and in essence the article speaks of the ...
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151 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 ...
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79 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 ...
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5k 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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2answers
78 views

What happens when the brain is no longer capable of co-ordinating or regulating the heart and breathing rates? [closed]

Does the heart no longer function? Does it go into ventricular fibrillation? What happens?
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84 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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35 views

About a mechanical aid to the heart

I saw a news story a few years ago (I think) about a girl with a poor heart having a device implant that took over only some of the functioning of her heart ( I think they called it a piggy-back ...
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758 views

In an open circulatory system, how is blood moved?

In the mollusks section, the powerpoint mentioned that gastropods and bivalves have an open circulatory system. According to the note, this means that the blood does not travel in vessels. How, then, ...
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70 views

Why are Lymphatic trunks part of the Cardiovascular system?

According to Wikipedia the Terminologia Anatomica (international anatomy standard) the lymphatic trunks are part of the cardiovascular system instead of the lymphoid system. Why did they make that ...
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167 views

Is Sinus node conduction necessary for heart beating?

Assume a patient with previous cardial infaction which SA node not possible to activate action potential anymore. However, SA trying to beat unsuccessfully repeatedly waisting energy. Therefore, I ...
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110 views

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

I know what the cardiac cycle is. There are two phases diastole and systole. One is the relaxed, and the other is the contracted form of the heart. The diastole is where blood is pumped to the ...