Questions tagged [cardiology]
The study of the physiology and pathology of the heart and the cardiovascular system.
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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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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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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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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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Do afterload and stroke volume form part of a negative feedback loop in blood pressure regulation?
Blood pressure is the product of cardiac output and total peripheral resistance:
$\text{BP} = \text{CO} \times \text{TPR}$
Since cardiac output is the product of heart rate and stroke volume, we have:
...
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Why do people perceive blood pressure as the force that moves the blood forwards (see details)?
For example "Veins contain a lot of valves because the blood pressure inside them is low.". This wouldn't make any sense unless if blood pressure was perceived as the force that drives the blood ...
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How does the SNS increase the heart rate when it causes an increase in cellular uptake of potassium?
Since β-Adrenergic stimulation increases cellular uptake of potassium, this will reduce the plasma concentration of potassium. Thus, a more negative membrane voltage will arise as the potassium ions ...
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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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Consequences of abnormal blood pressure unrelated to cardiac output?
A question from Kaplan's MCAT Biology Review asks:
In bacterial sepsis (overwhelming bloodstream infection), a number of capillary beds throughout the body open simultaneously. What effect would this ...
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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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The heart of a Pigmy Shrew beats 1300 per minute then why is it so fast?
A pygmy shrew is such a small animal. Even with such fast heart beats their average life span is 1.5 years. So can we consider faster heartbeats to not be good for health?
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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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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 ...
user3800
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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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sympathetic nervous system and vasoconstriction
At the moment I am very confused and I would highly appreciate any explanation.
When the sympathetic nervous system is activated because we are for example exercising, our blood vessels constrict. The ...
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Trouble in understanding graph of pressure time in different chambers of heart
In the book, it is written that from 0 s to 0.125 s-Atrial Systole; 0.125 s to 0.325 s-Ventricular Systole; 0.325 s to 0.6 s-Ventricular Diastole
Why a bump is there from 0.125 s to about 0.175 s in ...
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What is the function of the Moderator band?
The moderator band in the right ventricle is a band sorts of muscle which consists of a significant branch of the AV bundle. Does it mean it delivers impulses to the anterior papillary muscle faster? ...
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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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Why is mean systemic filling pressure used to calculate pressure differential for venous return?
I'm really struggling to understand venous return curves and their relationship to mean systemic filling pressure.
I understand mean systemic pressure is the pressure that would be measured throughout ...
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A hypothetical emergency situation
This question was posed to me by my Biology teacher:
Consider a hypothetical emergency situation of a person shot by a bullet in the heart. The bullet goes into the body and comes out from it, ...
user29365
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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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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 in ...
user12874
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Why is pericardium muscle repolarizated earlier than endocardium? [closed]
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
...
user12874
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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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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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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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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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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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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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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 ...
user661
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Flow of left ventricle into the aorta
I am currently practising for an exam and am having trouble understanding one of the exam questions:
The table gives the blood flow rate in various parts of the fetal circulation.
Flow rate in mL min-...
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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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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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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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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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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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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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What benefit do cardiomyocytes accrue by requiring calcium induced calcium release (relative to skeletal myocytes)?
According to 2 sources I've read, in contrast to skeletal myocytes, cardiac myocytes need calcium to diffuse in to result in contraction. One source says that they need large amounts of calcium to ...
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How can I simulate heart electrical activity in a 2D plane?
I am not a biologist/medical student, I study software engineering. But I really like when medicine and engineering hold their hands together to achieve great things.
As a side/toy project, I was ...
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What drives max heart rate on beta blockers?
In a healthy human being, the increase in heart rate from rest to around 100 to 110 beats per minute at low intensity exercise is due to withdrawal of the parasympathetic nervous system's influence. ...
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How much do arteries expand during pulse?
Arteries expand during a pulse. The amount of expansion may differ from artery to artery. How much do arteries expand? I understand it might be a range. Inform the same. Even values specific to some ...
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Why does fetal distress (hypoxia) cause bradycardia?
In a non stress test performed in the labor room, fetal bradycardia is a danger sign indicating fetal distress (hypoxia).
Why does fetal hypoxia cause bradycardia while hypoxia in adults cause ...
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Left Ventricle vs. Right Ventricle size in different Animals [closed]
Why are the right ventricles in chicken hearts significantly smaller than the left ventricles, whereas in cows the two ventricles are of roughly equal size.
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Would a hole in a heart make it unsuitable for transplantation?
Would a hole in a heart instantly make it unsuitable for transplantation? Or could it be possible for a heart with a congenital defect to still be suitable for use is someone else's body?
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Why are valves preferentially affected in endocarditis?
The inside of the heart is covered by endothelium throughout. Why are valves predisposed to endocarditis? I know it can affect other structires like the septum, chordae etc. But why the valves? ...
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Plaque rupture flow chart reading
I am having a bit of trouble interpreting flow charts given in my biology question sets.
Given the following stimulus
The Question is :
In which of the following options does each substance play ...
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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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Why can we control our breath rate but not our heart rate? [closed]
Even though we cannot survive for more than few minutes if we stop breathing or if our heart stops, why is it so that our heart beat is controlled involuntarily while breathing can be voluntarily ...
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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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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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