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Questions tagged [cardiology]

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

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Are there toxins that cause heart attack and/or stroke in multiple individuals in short time frames?

Are there any known environmental factors that would cause more than one person to have a heart attack or stroke within a short period of time (e.g. 2-3 months) of one another? I'm particularly ...
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10 views

Does sitting up increase venous pooling in the legs? Would there be less venous return to the heart on sitting up? [on hold]

Does sitting up increase or decrease the venous pooling in the legs. As the subject is not sitting or standing wouldn't there be no change?
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1answer
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Will being very muscular (to the point that one is characterised as obese by BMI) increase blood pressure?

It is widely accepted that obesity/overweight (which I believe refers to people with a high amount of fat cells instead of bodybuilders who weigh a lot due to lots of muscle cells) have higher blood ...
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1answer
25 views

Why does atheroma contain thromplastin/tissue factor?

From my understanding, when the endothelial lining of arteries is damaged, atheroma is formed at the site of the damaged area. If the atheromas is ruptured, thromboplastin contained in atheroma is ...
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28 views

Alcohol effect on heart and vascular system

How does alcohol weaken heart muscles and why does it increase blood pressure both temporarily and long term? Is the long term effect due to increase of plaque or is it due to other effects?
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58 views

Can the heart generate its own rhythm independent to the SAN?

My textbook and a revision guide, which I believe is a reinterpretation of the textbook, state that: The SAN initiates waves of excitation that usually override the myogenic action of the cardiac ...
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3answers
92 views

Why do our bodies maintain blood pressure but not the flow rate?

This might be a silly question but i'm not not clear I'm always told that blood pressure is homeostatic parameter and can't not be changed but isn't what important is the flow rate to the organs? ...
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1answer
17 views

The detail about the exact time of heart attack

Storage of cholesterol in coronary artery tends to heart attack. But in which phase heart attack occurs? Why only a definite time is called heart attack? Why this is the extreme point of coronary ...
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1answer
18 views

ECG detection using minimal number of electrodes

Disclaimer: Hello, I'm someone from an electrical engineering background, so this question may sound dumb. I wish to make a wearable ECG monitoring device for arrhythmia detection. Since the device ...
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2answers
191 views

Does blood clot reduce blood flow?

I read that blood clot reduces blood flow from few website and from doing an A level biology question; and if this blood clot is formed in pulmonary thrombosis, this can reduce gas exchange in lung. ...
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How does alcohol interact with sympathomimetics to affect the cardiovascular system?

There is a fair amount of information on the cardiovascular effects of alcohol, and of sympathomimetics. How do they work? And how do their mechanisms interact? We know that similar pathologies ...
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1answer
86 views

How does the cardiac cycle and electrical activity all relate to blood pressure in the heart? [closed]

I know how the cardiac cycle works and understand the electrical activity in the heart such as the AV nodes, SA nodes and Bundles, but how do they work together in relation to blood pressure?
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1answer
39 views

Structure separating the left atrium from the ascending aorta?

With reference to the (adult) anatomy of the human heart: The left atrium (LA) and the proximal part of the ascending aorta (Ao) abut one another, as shown nicely in this image [1]. Is there a name ...
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1answer
91 views

How does vasoconstriction retain heat?

I am reading on vasoconstriction on wikipedia. The article states that: When blood vessels constrict, the flow of blood is restricted or decreased, thus retaining body heat or increasing vascular ...
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1answer
137 views

What does “dissipated” mean here?

This is the context: You know cardiac muscle cells are small cells relative to skeletal muscle cells, but unlike skeletal muscle cells that are arranged in parallel and their contraction is ...
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1answer
48 views

Turbulence in blood

Turbulence in blood flow is known to indicate diseased or obstructed arteries. Techniques to measure turbulence in blood flow are mostly based on turbulence kinetic energy measurments using MRI [e.g., ...
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115 views

Understanding beat annotations of arrhythmia ECG dataset

I'm trying to understand the rhythm changes in the MIT BIH dataset. In annotations, there are 2 main types. Beat annotations and rhythm annotations. Rhythm annotations (aux_notes field) contains ...
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1answer
591 views

Heart rate vs body size

It is known that large animals have lower heart rates (beats per minute) than small animals. Is it the same situation in humans? That is: if we have a group women, about the same age and fitness, ...
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43 views

Anatomy of heart

What is an auricle and is there any similarity between auricle and ventricle or atria because in my anatomy book many times the author refer to auricle as ventricle?
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36 views

Understanding hyper- vs hypokalemia

After searching the web for a while, I found that: Hypokalemia results in a prolonged Q-T wave interval Hyperkalemia results in a peaked T wave and a wide QRS complex Now, I'm trying to understand ...
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How to obtain normalised ECG given ECG readings across lead 1, 2, and 3?

I saw this youtube video on ECG readings and cardiac dipole vector locus of the heart across the three leads. Posting screenshots from it: My question is how to obtain the graph (2nd image) from the ...
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1answer
29 views

Using formulas to explain why contraction of blood vessels leads to increased blood pressure

I know, I know this is probably a question too simple to be asked on a forum like biology stack exchange. Problem is, I looked many places and can't seem to find a more mathematical approach to ...
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3answers
366 views

Why is the heart adversely impacted by chronic psychological stress, yet it benefits from routine physical exercise?

Chronic psychological stress is commonly said to be deleterious to the heart, and predispose one to cardiovascular disease. Yet the opposite is said about regular aerobic exercise. Physiologically, ...
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0answers
39 views

Pain and Angina Pectoris

What causes pain in an angina pectoris? Ok, heart muscles may lack oxygen, but what is the role of pain here? Is it being beneficial? I'd like to know the physiological process of induction of pain ...
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32 views

Prepotential in cardiac cells

I came across this MCQ in my physiology book, it says: Prepotential ........... a. is present in ordinary ventricular muscle fiber b. slope is decreased by sympathetic stimulation c....
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1answer
138 views

The 4-chambered heart

Birds and humans have a four chambered heart. All animals having 4-chambered hearts are warm-blooded. Why are crocodiles an exception? Why are they cold-blooded even though they have a 4-chambered ...
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1answer
139 views

what is the difference between osciloscope and electrocardiograph?

I am completely confused about these two devices! as far as I know, oscilloscope and electrocardiograph, both, show the heat waves(P, QRS, T) so what is the difference between their job?
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effect of arterial vasocontriction on the pressure in arteries

if experimentally one induces smooth muscle contraction on an artery and cause it to constrict, keeping the cardiac output same and also the arteriolar resistance(total peripheral resistance) the same ...
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law of laplace and pressure developed in arteries

in arterioles the pressure depends on the impedance of the vessel(elasticity and youngs modulus) cardiac output pre arteriolar resistance what i want to ask is will the pressure also depend on law of ...
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679 views

Why is the body cooled during cardiac surgery?

When undergoing cardiac surgery, the heart is disconnected from the blood circulation and blood is passed through a heart-lung machine and cooled so that the body temperature of the patient is reduced....
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1answer
200 views

why do sodium channels close with excessive extracellular potassium ions in cardiac myocytes?

When there is an excessive concentration of potassium ions outside cardiac myocytes, the membrane potential surely goes up. I would have thought that this would make it easier for the membrane ...
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1answer
83 views

Cardiac pacemaker: how can different nodes have different frequencies?

Primary SA node creates 70 beats per minute and secondary AV node 40-60 beats per minute. Is the AV node inactive (and other subsequent nodes) while the SA node is functional? If the primary, ...
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1answer
481 views

Effect of hemoglobin on colloidal osmotic pressure

If Hemoglobin gets out of RBCs, my book says that colloidal osmotic pressure of plasma increases. Hence, filtration of fluid across capillaries is prevented. So the heart increases its work to be ...
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22 views

How does heart rate change when entering N1 sleep?

I would like to know how the heart rate changes as a person enters N1 (NREM 1) sleep from a wakeful state. The focus is on entering N1, and it would be great to have time-series data to see the ...
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Do blood vessels expand during angiogenesis?

I know that there are two usual ways of creating new blood vessels: A new vessel sprouts from the wall of an old one, A wall of cells grows down the middle of a vessel, splitting it into two. I also ...
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Is this an ectopic beat? [closed]

First of all, I am unclear as to whether the answer to this question is a matter of fact or of opinion. Nevertheless, I hope to find the answer. In the image below, is the green beat considered ...
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1answer
38 views

Seizures and blood pressure

A seizure is basically a synchronized firing of neurons as opposed to the more common unsynchronized firing taking place during normal neural activities. However, I am uncertain if the exact technical ...
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152 views

Why no increase in venous return even at high negative pressure?

Why is it that even at highly negative the venous return remains the same ? i.e Why even very negative pressure is in the right Atrium cannot increase the Venous return significantly above that ...
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0answers
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Why does the posterior region and the right ventricle of the heart are not well represented in standard 12 leads?

When assessing an ECG we divide our 12-lead into four main contiguous lead groups: inferior, lateral, septal, and anterior. Regions not well represented on a standard 12-lead are the posterior region ...
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357 views

Why is the pressure pulse bigger after exercise?

Right after exercise, is the amplitude of the pulse smaller or bigger than resting period? And why is that ?
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733 views

Why repolarization in ventricles start in last area which is depolarized “epicardium ” rather than first area “endocardium” [closed]

About ventricular repolarization , l know it start in the last area which is depolarized ( that is why it has positive deflection on ECG ) but the question is why it start in that area ( epicardium ) ...
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1answer
179 views

Is a one ventricle heart feasible?

So this is derived from a lesson at Khan Academy. The mind activity assumes that the one ventricle heart pumps blood to the lungs for oxygenation then rest of the body. However, the problem is that ...
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369 views

Pressure change in atria

Background:It is said that during the phase of isovolumetric contraction , due to sharp rise in the ventricular pressure, there occurs bulging of AV valves into the atria producing a small but sharp ...
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444 views

Why does an increased heart rate mean increased blood pressure?

Say a person starts exercising. If their cardiac volume remains the same but their heart rate increases so that the overall result is an increase in cardiac output, will their blood pressure increase ...
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Why is the heart not in the middle of the body?

All mammals that I can think of have a high degree of bilateral symmetry (In fact, almost every animal I can think of is like this). So why is the human heart not exactly in the middle of the body? ...
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Human anti animal antibodies issues in blood testing

Do people have to be exposed to animals to get HAMA antibodies? Can these antibodies impact blood tests with false negatives as well as false positives?
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2answers
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At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'?

According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed. But according to this article, the heart ...
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2answers
343 views

How does heart beat faster while doing a strenuous task?

I know that when we do tasks which require extra physical effort (like running etc.), our heart beats faster. I also know that the reason behind this is that these jobs require more energy than usual ...
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1answer
25k views

How can heart disease cause excessive sweating?

According to google: What can cause sudden sweating? Excessive Sweating. A person with excessive sweating has a condition called hyperhidrosis. ... In adults, the most common cause of ...