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

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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 ...
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19 views

To measure Na/K channel activation in membrane level?

Assume that there are two different signals going on in the ECG - during depolarisation and repolarisation in the standard ECG. I got an advice that do not use the standard ECG in measuring exactly ...
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24 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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49 views

Could below zero decibel environment cause arrhythmia?

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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35 views

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

My conjuncture 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 ...
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32 views

How do the symptoms of Sepsis affect heart function?

I have intuition that Sepsis with infection can cause spastic functioning of heart during systole heart working spontaneously in snatches during systole atrial fibrillation first contraction of ...
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55 views

How do cellphones calculate heart rate?

How do cellphones calculate heart rate ? I understand that the cameras there try to count undulation in blood flow, but is the method of calculation same as that of professional SpO2 monitors ?
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30 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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50 views

Cardiac ECG database with high sampling rate?

MIT-BIT arrhythmia database follows AAMI standards. It has samples of 360 sampling frequency so it can detect heart beats of 180 Hz because of Nyquist frequency. I have noted that this frequency ...
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72 views

Sodium levels and blood pressure

Why does low $\ce{Na+}$ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of $\ce{Na+}$ cause hypertension or high blood pressure? From what I ...
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33 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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37 views

Can we make any judgements about sleep or readiness to sleep from a heart rate metric and/or pulse oxymetry?

I'm looking at inexpensive and un-intrusive ways to quantify the state of human body/mind . One of these is Actigraphy, which is a study of human motion over time. This can be done with an iPhone ...
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12 views

How 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 conjuncture is that calcium transforms between two phases ionated phase (free calcium from ...
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22 views

Projection space of ML II channel in ECG

I am trying to find the approximate effective 3D region of the heart that is drawn from the ML II channel of the standard ECG either by using many channels or using one channel only (not possible ...
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10 views

To decrease the amount of proteins in the lymphatic drainage for short term

I am looking for some mechanism which can decrease the amount of proteins in the lymphatic drainage only for short term. Assume there is no flow between capillaries and lymphatic system because the ...
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26 views

Are there naturally occurring Biological Pacemakers?

There are artificial biological pacemakers which express funny channels. I am thinking if it is possible to have also naturally occurring (only in recovery cases and in silent tissues) biological ...
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10 views

Mechanisms to start simultaneous depolarisation of two Pacemakers?

I am thinking the biochemical mechanisms of the simultaneous depolarisations of two pacemakers. My intuition Funny channels (but not alone) No autonomic nervous system (my conjencture) What are ...
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11 views

What is the entry location into the heart for different autonomic stimuli?

I first had an intuition that the entry location is near sinus node, but now I am thinking that the location is near AV node, at least for some myocardial infarction patients. Physically, it is a more ...
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14 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 conjuncture is that the mechanism is the ...
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22 views

Which reflex arcs work in Heart with extrasystoles?

I am researching what is triggering the extrasystoles - initial idea from this thread about Which ionic channels of Pacemakers can work in very low frequencies in extrasystole? I am interested in the ...
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31 views

Simultaneous depolarisation of Sinus Node and AV node as extrasystole in myocardial infarction patient

Assume you have a patient 68 years old with previous myocardial infarction (Actually patient 201 in MIT-BIT arrhythmia database). Assume that AV node depolarises strongly. However, at the same time, ...
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14 views

Calling for Pressure pictures about Right and Left atrium

I am trying to understand the partially patent foramen ovale in patients with right-side heart failure. I am interested how the pressure in right and left atrium change in normal case in abnormal ...
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20 views

Laser surgery to stop damaged Sinus node from beating

I am trying to find any publication about laser surgery to stop the damaged sinus node which cannot anymore beat. I could only find publications which modifies SA node function. I am not sure if it ...
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28 views

Normal Frequencies in Heart

I am trying to visualise possible ranges of frequencies from different structures of heart: different valves and their possible frequencies heart sounds I - IV and their normal frequencties what can ...
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29 views

To define the total Resistance of Systemic Blood Circulation

Some systems are in parallel so let's just call those like $R_{\text{lungs}}$. I got this formula $$R_{\text{total}}=R_A+R_a+R_c+R_V+R_v$$ where $R_c$ capillaries, $R_a$ arterioles, $R_A$ Small ...
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51 views

Why is the resting membrane potential of cardiomyocyte more stable than that of Pacemaker in Phase 4?

There must be some channels that keeps this very stable. It seems to be that the resting membrane potential of pacemaker cells is steadily increasing until the threshold voltage. I think the same must ...