Hot answers tagged cardiology
10
The basic reason is osmosis, the tendency of solutes to move from an area of high concentration to one of low concentration across a permeable barrier. So, ingesting large amounts of salt results in a high sodium concentration in the blood stream. This in turn causes water to enter the blood vessels by osmosis. More water in the blood means a greater volume ...
9
It is easy.
Method A, simple, is based on "counting the fish in the pond" method.
Make rough estimate of amount of blood in the organism.
Choose a component of blood that is replenished slowly [from liver or marrow etc]. That takes time to replenish. Red blood cells are probably OK. Some easily measurable and slowly replenished component of blood. Let's ...
8
Polynomial gives a good hint. By adding in a known tracer of known amount that should only circulate in the blood stream, the concentration of the tracer when completely distributed will give the volume of distribution.
If the tracer only stays in the bloodstream (and that's a fairly large IF), then the VD will be equal to the VBlood. However, as many ...
8
Trans fatty acids are digestible, but they cause an increase in LDL and a decrease in HDL, which is the leading mechanism for atherosclerosis. So, they increase the risk of a cardiac infarct.
LDL means Low Density Lipoprotein, it's one of the 5 major lipoprotein groups. Lipoproteins carries the fatty acids and cholesterol which were absorbed from ...
8
Simple answer, yes.
It really is a matter of how technical you wish to be. By defintion, all arterial flow (except the pulmonary artery) conveys blood away from the heart. The largest arteries exhibit the Windkessel effect which allows for the compression-basaed effects that bobthejoe inferred. Explicity, as blood is pumped out of the left ventricle, it ...
7
Quick answer, no.
Imagine a balloon; as you compress the balloon, there will be a lot of air that leaves it. But as you let it relax, the balloon pulls in surrounding air even as you fill it from another side. When the aortic and tricuspid valves are closed, there is blood flow forward but due to conservation of mass, the blood goes back to fill in the ...
5
I would be very surprised if the time of day made a difference. I've personally never heard mention of such a phenomenon in discussions with intensive care practitioners (where of course HR and BP are measured constantly). However this is only the case during rest, this paper (on horses) suggests that there is some difference in HR and BP after exercise ...
4
Because of reflected pressure waves and the stiffness of the blood vessel. The forward pressure wave from the heart travels much faster than the blood itself and is reflected at areas of tapering and branching. This backward wave slows the forward flow of blood, and at the same time, when it meets the next forward pressure wave, that forward pressure wave ...
4
The number you are looking for might be quite large depending on the level of detail you demand for the measurement. There is no single number for the area of most objects in fact.
The importance of fractals is much related to the question of what is the perimeter or surface area of something. The classic example is trying to determine the length of ...
3
Cleaning the tail with ethanol is of some help and also, as you said, warming the tail. We sometimes put one of those flexible lamps (such as this) to heat up only the tail.
When anesthesized (ketamine/xylazine or isoflurane) we keep our mice on a heated pad anyways.
Cannulation in the tail does not sound like a good idea to me, especially if you are going ...
3
According to the Wikipedia page on Supraventricular tachycardia the heart can go to a new faster rate in the space of a single beat, and then come down again just as quickly, as shown in this image taken from the Wikipedia page.
3
In relation to the cardio vascular system a combination of adrenaline from exercise and the bodies natural response to the cold causes constriction of blood vessels in the skin and extremities. This helps to reduce heat loss.
The movement from running increases the amount of cold air that runs across your body and into your lungs, which would offset the ...
3
No, the beats originating outside of the sinoatrial node are not considered for pNN50. Moreover, this metric cannot be applied to the rhythm featuring any type of ectopic or non-sinoatrial activity.
NN50 has its name from an acronym "normal-to-normal", this acronym is used instead of RR ("from R to R") to emphasize that only the normal, e.g. sinoatrial ...
3
I am not sure if I understand your question correct. What I can see here is a clear ST depression, that might be indicative of myocardial ischemia/infarction. The underlying mechanism is the shortage of oxygen in myocytes leading to elevation of resting potential and slowing of the depolarization -- this accounts for the elevated baseline after T.
I am not ...
2
The cardiovascular system is affected by three types of pressure. These are:
Heamodynamic - caused by the contraction of the heart, which would give the view of pressure being higher closer to the aorta as in Kevin's answer and my first thought too.
Kinetic - caused by the action of skeletal muscles in movement in squeezing primarily veins to return ...
2
I think you are correct to discount your first point as the cellular respiration proceeding to supply your muscles with ATP when running will produce heat anyway, as you say.
As to the lungs having to work harder in cold conditions, its an interesting proposition. I would hypothesise that this may indeed be the case:
Gas exchange across the lungs occurs ...
2
Although there is clearly no feasible mechanism for such a phenomenon, there is good evidence that transplant patients can believe in some sort of transference of qualities from the donor. See for example (my emphasis):
Inspector, Y. et al. (2004) Another Person's Heart: Magical and Rational Thinking in the Psychological Adaptation to Heart ...
2
In terms of cell bodies? Zero. There are autonomic projections from the spinal cord (sympathetic) and vagus nerve (parasympathetic) to the sinoatrial node, the atrioventricular node, and at discrete points in the atria and ventricles.
2
The diaphragm moves down during inspiration. This leads to air being sucked in, due to the pressure difference created. The converse is true during expiration. As the thoracic space is where the SVC sits, it's pressure decreases during inspiration as it is subjected to the surrounding decrease in pressure.
2
Homocysteine:
Causes endothelial dysfunction and damage
Accelerates thrombin formation
Inhibits native thrombolysis
Promotes lipid peroxidation through free radical formation
Induces vascular smooth muscle proliferation
Promotes monocyte chemotaxis
Many observational epidemiological studies indicate that individuals with higher Homocysteine levels have ...
2
It kind of depends. If you want to compare apples to apples, check it first thing in the morning. However, that's going to be at the lowest point. It's also important to know what your blood pressure is during the day, when you're living your normal daily life. I recommend checking fairly regularly in the morning so you'll know what your true baseline is ...
1
A number of things can be seen. Ischaemia is typically caused by the narrowing of blood vessels that prevents perfusion (blood flow) to the heart or other organs. When the heart muscle doesn't get enough oxygen, the walls of the heart might not "beat" (i.e. contract) properly. We observe this and thus can tell if a coronary artery is reduced or blocked or ...
1
Coronary artery disease thickens the wall. Flow is dramatically affected by thickness (radius to the fourth power). In an echo you observe the heart muscle i.e. does it contract normally using the surrounding muscle and baseline as a comparison. If the wall is thickened, this will cause a decrease in perfusion which will result in the heart muscle ...
1
Actually in my research into circadian events, the hourly differences in blood pressure was the first thing that I found. Based on this, I'd state that there are hourly differences in blood pressure and cardiovascular efficiency.
Because these changes are circadian, measuring these values at the same time every day (ex: 1 hour after wake up time or 1 hour ...
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