Questions tagged [cardiology]

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

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13 views

Why does higher venous volume increase atrial pressure?

If the cardiac output stays the same, then why does higher venous volume increase right atrial pressure? Shouldn't the flow rate be conserved (with a constant cardiac output) so that the venous return ...
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Does increasing contractility increase LV ESP?

I see many PV diagrams showing a negligible difference in the ESP when contractility increases. I'm wondering why this is the case, because if more blood is being pumped out into the aorta, the MAP ...
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Is atrial natriuretic peptide relased when we drink water?

I know that osmolarity is controlled by the hypothalamus and recover by ADH which reabsorb water. It also can be released when ECV is very low. ECV/salt is controlled by aldosterone/atrial ...
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20 views

Vasoconstriction and blood flow

The resistance in a blood vessel is equal to the pressure difference divided by the blood flow. Let us now say that a sympathomimetic causes vasoconstriction which increases the resistance. Does this ...
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28 views

How does the cardiovascular system improve upon repeated, strenuous exercise?

New here, hopefully this is the right place to post this question. It's widely known that repeated, strenuous aerobic exercise gradually improves the capacity of one's cardiovascular system — $\text{...
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How to define Bigeminy

Firstly, do cardiologists actually count how many bigeminy when they diagnose? Secondly, since bigeminy only exists when there are recurring pattern, do cardiologists count two or three bigeminy in ...
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53 views

Can anybody recognize this cardiac waveform? [closed]

Is this an artifact or an arrhythmia?
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89 views

Difference between Premature Atrial Contraction and Atrial Fibrillation

what is the difference between Premature Atrial Contraction and Atrial Fibrillation. I know that both have irregular heart beat but have normal QRS complex. Both have abnormal or absence P waves but a ...
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1answer
34 views

Definition for different arrhythmia

I am wondering if there is an organization, a document or a research that standardize all the rhythms? Such as describing how long should the ECG be flatline to be considered as asystole? The rhythm I ...
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218 views

How are monocytes larger than capillaries?

I have read that the average size of a capillary is about 8 micrometers. How is it possible that the 15 micrometer or so monocytes in blood do not block these vessels? https://en.m.wikipedia.org/wiki/...
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30 views

For how long can the heart be in asystole and then restart itself?

The medication Adenosine is used for the treatment of some abnormal heart rhythms. However, according to Wikipedia, it can cause asystole for a few seconds: Because of the effects of adenosine on ...
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Is the medium which transmits the electrical impulse through the heart different to a nerve?

According to Nerve A nerve is an enclosed, cable-like bundle of nerve fibres called axons Being an Axon An axon (from Greek ἄξων áxōn, axis), or nerve fiber, is a long, slender projection of a ...
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Why does repolarisation of the heart start from the point where depolarisation ends?

Depolarisation moves from the atria to the ventricles and ends near the atrioventricular fibrous tissue after completing a swooping motion However, repolarisation first begins where depolarisation ...
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what are best methods for mrsa screening in hospital?

methods for screening MRSA are based on PCR (mecA detection) and MRSA latex test and culture. I need to know sensitive, specific and cost-effective methods for diagnosis MRSA infection on one work day ...
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106 views

Cardiac cycle and atrial contraction

During atrial contraction ("a" in the figure), why does the ventricular pressure match the atrial pressure? The ventricular pressure generally stays the same throughout passive filling until it ...
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103 views

Is returning cholesterol to the liver really performed by HDL?

Various answers in biology SE, including two quite upvoted ones (1, 2) claim that (in humans) returning cholesterol to the liver is done by HDL. If I understand correctly, Wikipedia's Reverse ...
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239 views

When endothelial cells in blood vessels (arteries or veins) are damaged, does atheroma form first or blood clot?

I have learnt from Khan Academy's video on atheresclerosis that when the endothelial cells of an artery are damaged, atheroma forms at the site, and if the atheroma’s fibrous cap is ruptured, ...
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21 views

Can the heart and other muscles function without creatine/phosphocreatine?

Skeletal muscles in the body have a small reserve of ATP. During the first few seconds after contraction, phosphocreatine is used by the enzyme creatine kinase in order to phosphorylate ADP to ATP ...
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68 views

How do veins's valve pocket sinus tend to become hypoxic?

For context, this question relates to the formation of deep vein thrombosis as I read that hypoxemia in vein can trigger coagulation cascade and cause a thrombus to form in vein. I read that vein's ...
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20 views

How does a stronger heart reduce the risk of CVD?

I read from websites and articles that exercise will make your heart stronger thus your heart will use less effort to pump blood around the body per heartbeat thus reduce risk of CVD. However, how ...
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36 views

Cardiopulmonary reflex

Cardiopulmonary receptors (CPR) locate in the junction of great veins (IVC/SVC/PV) to atria. They are also known as low-pressure receptors. They detect the increase of preload to atria. Statement 1: ...
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32 views

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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49 views

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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35 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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92 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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124 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
199 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
21 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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40 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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318 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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86 views

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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157 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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65 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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164 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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232 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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65 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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232 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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1k 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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112 views

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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32 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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651 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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51 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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294 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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310 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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50 views

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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98 views

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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1k 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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328 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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195 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, ...