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11

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 ...


11

Simple answer, yes. It really is a matter of how technical you wish to be. By defintion, all arterial flow conveys blood away from the heart. The largest arteries exhibit the Windkessel effect which allows for the compression-based effects that bobthejoe inferred. Explicity, as blood is pumped out of the left ventricle, it stretches te aorta, and this ...


10

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 ...


10

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 ...


9

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

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 ...


8

Lipids require more oxygen to burn, but also they are cheaper to store (since they have great calorific power than carbohydrates and they're hydrophobic, thus not requiring water for their storage). The body can store so much lipids that it becomes an almost everlasting energy source (A normal adult have enough energy stored as fat to allow basal metabolism ...


6

Insects primarily get oxygen through diffusion of air through their skin. I doubt the antennae need hemolymph circulation.


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 ...


5

Insects do not posses closed circulatory system, but a space where organs float in a fluid called hemolymph. They don't have blood vessels (but some arthropodes have pumps that act a like heart). The hemolymph allows nutrients and excretion products to diffuse, but usually doesn't serve as a means to transmit oxygen to the tissues. In insects, the oxygen is ...


5

There are many reasons why the maximal heart rate decreases with age. The most prevalent is the heterogenous thickening of the walls of the heart. Cardiac output is stroke volume times heart rate. When the wall thickens, the heart needs more energy to achieve the same pumping (bigger stroke volume) or it needs to increase heart rate at rest. Because of ...


5

The normal cardiac cycle is comprised of two distinct phases: the systolic phase in which the heart contracts, ejecting the blood, followed by the the diastolic phase when the cardiac muscle relaxes, refilling the heart with blood. This cycle is assured by specialised cardiomyocytes (Cardiac muscle cells) that conduct electrical impulses through the heart. ...


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 ...


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

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.


4

The purpose of valves is to maintain blood pressure against gravity until it reaches the heart. The Superior Vena Cava (SVC) inlets exist above the heart, and any valves would only prevent gravity from helping bloodflow. The Tricuspid prevents blood from the SVC from just directly flowing into the Right Ventricle. As a note: The Eustachian Valve either ...


4

This is a specific version of the great cancer question: "Why are some cancers more common than others?" The answer is either "Some have more common causes", and (or) "Some are cured spontaneously more often". So now all you are asking is "What causes cancer?" and "How do we cure it?" Given that, I don't expect a general definitive answer will be ...


4

I recognize this was asked like 7 months ago, but in case you're still looking for a good resource: I used a CD of heart sounds that is called something like "Harvey Heart Sounds," which I got with the purchase of my stethoscope. If you can find a copy of this, I found it an excellent tool when training to recognize the differences. These are good heart ...


3

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.


3

According to this source, gold is not a necessary trace element for living organisms. Would have been cool, though...


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

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 ...


3

This paper from 1991 is intervention-based, so it reports the effects of behavior modification on lifespan in people who turned 35 in 1990. The authors report the gains for each individual behavior and then say: Eliminating coronary heart disease mortality is estimated to extend the average life expectancy of a 35-year-old man by 3.1 years and a ...


3

The definition of "vascular" is as follows:- of, relating to, affecting, or consisting of a vessel or vessels, esp. those that carry blood: By this defninition, the cardio-vascular system doesn't need to include only the blood vessels and the heart. It includes all conducting and distributing vessel elements including those which carry the ...


3

In a closed circulatory system, all of the blood stays within blood vessels or the heart itself. Organisms that have open circulatory systems, such as arthropods, have hemolymph (a fluid that is essentially a mixture of blood and interstitial fluid). The hemolymph actually does travel in vessels for a very short amount of time, as it is leaving the heart. ...


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 ...



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