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The brain is indeed stacked with blood vessels, as shown in a 3D model in Fig. 1. Fig. 1. 3D-printed model of blood vaculature. Source: Biobots. The blood supply on the surface of a live brain is readily seen during a craniotomy (Fig. 2.) Fig. 2. Surface of the brain. Source: The Sterile Eye. When freshly prepared, the interior of the brain appears ...


22

Short version The heart has the ability to beat independently of the brain as long as it has oxygen. The heart will eventually stop beating as all bodily systems begin to stop working shortly after brain death. Remember the heart can beat, but your diaphragm and lungs wont. hence the cardiac muscles undergo asphyxiation and die off. However, immediately ...


17

Your reasoning is sound and correct. The answer key is wrong. An unclotted blood sample needs something to prevent clotting. Extracellular calcium is required for both the coagulation cascade and platelet activation. It even has its own name in this context, Factor IV. This why EDTA, a calcium chelator, is used in some blood collection tubes to delay ...


10

Sydney Ringer showed in 1882 that when the heart, when separated from the body and immersed in lactated Ringer's solution, or even isotonic saline solution, will beat because it has its own pacemaker systems at the level of the Sinoatrial node and Atrioventricular node. This activity will continue until there is insufficient ATP to support it energetically. ...


9

Your image comes from the wiki page Aneurysm. The figure legend on the wiki page identifies it as: Angiography of an aneurysm in a cerebral artery I am not an MD so I chose to first dig up a similar appearing cerebral angiography with the aneurysm identified (dark protruding spot indicated by the arrow): Source: WestJEM, UC Irvine Taking into account ...


7

I think people can easily endure head-over-heel revolutions in space such as seen in Gravity. I am no mathematician (let alone physicist, both of whom could answer this more accurately) but here is my reasoning (faulty though it may be). You are assuming that someone would pass out from lack of blood supply to the brain. Given we have absolutely no ...


7

Technically 'lymph' is used to refer to the fluid found within the lymphatic system. If it's not in the lymphatic system, it is not lymph fluid. Thus, your question is really asking about interstitial fluid or the plasma that was filtered out of blood capillaries. The answer to your question is based on the Starling equation. Normally fluid leaves a ...


7

Atherosclerosis can develop in high pressure systems, such as arteries, and not in low pressure systems, such as veins. It is high blood pressure that can damage the lining of the blood vessel and initiate the process of atherosclerosis. BUT, atherosclerosis can develop in veins that have been used as grafts instead of arteries, for example, in a coronary ...


6

They aren't completely rigid and can change shape to squeeze through (see Downey et al). If they are activated, monocytes can get stuck in capillaries and block them, which contributes to poor circulation following reperfusion after an ischemic blockage (see Engler et al). Downey, G. P., Doherty, D. E., Schwab 3rd, B., Elson, E. L., Henson, P. M., & ...


5

There are 2 main reasons for using the Trendelenburg position when placing and removing a central venous line catheter into the subclavian or even internal jugular vein. Exactly what C Rags mentioned-- to increase the size of the vein. This position utilizes the force of gravity to pool blood towards the head from the lower extremities. This makes the vein ...


5

No. An individual blood cell will complete the whole loop but can take any route through the circulatory system to do this. For example, a blood cell leaving the left ventricle may immediately pass throughout the coronary arteries to supply the musculature of the heart or alternatively could carry on down the aorta. Another cell could be swept down the ...


4

Well, you're right! First of all, Nitrogen Bends or Decompression sickness (DCS) is a disease that arises as a consequence of bubbles forming within tissues. Inert gases, such as nitrogen and helium, enter the body through the lungs during inspiration. Increased BMI (Body Mass Index) implies an increased fat content of the body. This increased ...


4

I was wondering if a heart keeps beating if it is separated from the body? Yes, it does. Here's a video showing it (don't click if you're squeamish!): https://www.youtube.com/watch?v=NEuSCPifKhA It's a classical physiology experiment to remove a heart and keep it beating for some time in a jar with liquid solution. In fact, acetylcholine, the first ...


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 isn'...


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. ...


3

In adult/pediatric humans, no they don't. A good figure to get everyone on the same page was made by Cleaver & Melton: It is important to note that: In fact, endothelial diversity is reflected by vessel size-specific, organ-specific and even age-specific differences. (1) Developing blood vessels in the fetus can be a bit of a different story, and ...


3

As the comments pointed out, this is not a hard question to answer with some research, but I'll add a few more details. Dextrocardia is congenital. The human heart normally actually isn't so much on the left side - it's more pointed towards the left. In dextrocardia it points more towards the right side. This develops within the first few weeks of ...


2

From what I can make up from your question is that you assume the blood in the brain is a bad thing in terms of temperature control. It is not. On the contrary, blood circulation is crucial in maintaining brain temperature. Under conditions where the brain is heating up, which seems the focus of your question, there are mechanisms in place to extract this ...


2

In the capillary bed? Absolutely! In the venous return? Depends! I had to build one of these for class. In short: you can tell how oxygenated the blood is by its color, but you have to correct for how much blood there is: The dilation of the arterioles and capillaries with the heartbeat increases the size of the area being measured, and changes all sorts of ...


2

In order to clear some issues with the question and answers I add this one. The question itself was "will a heart keeps beating if it is separated from the body?" The answer to this question as it was asked: No, the heart removed from the body "as is" will stop beating almost immediately. Denervation and stopping oxygen and electrolytes supply will cause ...


2

The Sinoatrial Node is a ganglion (clump of nerves) attached to the heart, which regulates heartbeat independently from the brain (http://en.wikipedia.org/wiki/Sinoatrial_node). Heart rate can also be influenced by hormonal responses produced by the autonomic nervous system. To quote Wikipedia: While heart rhythm is regulated entirely by the sinoatrial ...


2

It seems that lungfish display the beginnings of a double circulatory system:


2

Yes, treatment of thrombus can cause embolism. Hypertension favors hemorrhagic complications. Thrombolytics: Yes, they can cause paradoxical embolism, although it is a rare complication [1]. The most fearful complication of thrombolytic medication is major hemorrhage. And hypertension favors bleeding [2]. Catheter-directed thrombolysis: Hypertension (...


2

The measurement that decreases during vasodilation is flow velocity, $v$, or a change in distance over change in time $\frac{\Delta x}{\Delta t}$. Prior to a reflex response, the same rate of flow, $Q$, or $\frac{\Delta V}{\Delta t}$ enters the capillary bed (here we use a capital V to represent volume, where $\Delta V$ is a change in volume, and $\frac{\...


2

Those arteries are (a) big enough for the catheters, (b) superficial enough (close enough to the surface of the skin) for catheterization. It would be quite a challenge to use the renal arteries, for a ridiculous example. There is also less of a risk of embolization than using an artery like the carotid, where embolism can cause stroke, which would be quite ...


2

Skin is extraordinarily tough compared to much of our internal tissues; it has to be to protect us. To bleed, skin integrity must be breached, which usually involves sharp objects. Think for a moment that most splenic or hepatic injuries (even complete ruptures) occur from blunt force trauma without breaking the overlying skin. For a more common example, if ...


2

Imagine the circulatory system is an amusement park ride. The ride is the left ventricle and the arterial system. After riding, people go around and get back in line to go again. The line and the building housing it are the venous system. Maybe the lungs are some sort of staging area where you get ready to get on the ride. The right atrium is the end of ...


1

Tissue factor is present in subendothelial tissue and leukocytes - in this case this would be within the atheroma since the atheroma consists of damaged endothelium. Tissue factor's presence in the subendotheilum in general implies that whenever the endothelium is damaged, tissue factor is released which promotes clotting at that site. Clotting starts after ...


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