Score
Title
270
AskScience Panel of Scientists XVIII
634
AskScience AMA Series: IAmA restoration ecologist focused on restoring oysters to the NY Harbor in New York City. AMA!
5914
How is it so that several (all?) mammals grow and lose a set of "baby teeth" before growing their final dentition? Why stop at two sets when other vertebrates such as sharks regenerate their teeth constantly?
9716
How does a master key work?
10
How does hydrogen embrittlement work?
3
Why does looking at bright things hurt our eyes?
55
If placed in a controlled environment, do trees that normally undergo seasonal leaf Abcission stop losing their leaves?
42
How do our eyes avoid being commonly infected through things like rubbing our eyes or the pollutants in the air?
8
Whats the difference between an explosive, a propellant and an accelerant?
8
Would it be possible to have a ball of electrons?
6
Statistical Regression: Why don't we care about the t-stat / p-value for the intercept term ?
7
How for down into the mantle do we have to go before the temperature is hotter than the surface?
3
Does Ocean Salinity Drop During/After a Rainstorm?
8
Are women born with all their eggs?
27
Do nocturnal animals prefer sleeping conditions that are dimly lit or bright in contrast to humans which prefer dark conditions?
5534
How does sunscreen stop you from getting burnt?
12
Would objects orbiting Earth, such as space debris, satellites, the ISS, be hot or cold to the touch?
12
How can we tell if someone we can’t see is shouting from far away or whispering close to us?
14
[Medicine] What leads a body to reject or accept donated organs?
22
How does a train engine, pulling miles of cars and many tons of load, get enough traction to actually move everything?
12
Why are shadows casted from objects more crisp depending on how far the object is from the ground?
17
How do phones keep cool with small heatsinks and no fans?
47
If the human body has evolved over millions of years to swell up in response to an injury, why are we instructed to apply ice to prevent our evolutionary swelling response?
3
What are public and private keys and what do they do for a server when transferring information?
9
Why don’t we sneeze in our sleep?
1
What is the shape of a transmissions wave? Can this shape be changed? Can motion significantly affect the shape?
24
Studies have shown that small movements in the throat occur during an internal dialogue--does that happen when music plays in your head, too?
1
Are there earthquakes in other planets?
4
How are enzymes like DNA ligase or DNA polymerase created in lab and sold in industrial scales?
5
How is hybrid fruit produced?
7
What is causing this orbiting water droplet in my tea kettle?
7
Are there more cases of depression in modern times than in history?
7
Why is cold weather usually synonymous with pneumonia infections?
4
Are there any videos from NASA or other space agency where they do tests in the vacuum of space? Such as a plant or mice or anything is taken outside of the space shuttle/station
4
Is there an explanation for why we have instances of an irregular body hair?
5
Can rare astronomical phenomena such as solar eclipses or supernovas disrupt biological cycles of living organisms?
3
Is there an upper limit to how fast a fluid can saturate paper through capillary action?
69
Why does sunburnt skin feel hot to the touch?
12
Air molecules travel at 1000 mph. Can we harness that kinetic energy?
8
Why is space and space travel illustrated, for the most part, on a horizontal line? Can't we space travel "upwards" or "downwards" and where would that eventually lead?
2
Why are Neanderthals depicted with dark skin? If they lived in Europe for longer than modern humans, why didn't they also evolve fair skin tone?
2
Could a container or cruise ship cause an orographic/rain shadow effect?
11 DrWYSIWYG There is a lot of bypass surgery that goes on not just the heart. Specifically for the heart the radial artery used to be used but it is being used less and less because the success rate is lower than vein grafts. This is because the diameter of the radial artery is so small that any narrowing (for example at the ends that are sewn into the original artery, or the anastomoses) can cause failure quickly. Veins are generally of larger diameter and have a better latency rate. Another responder to this question mentioned the internal mammary artery being used, which is true but a slightly different scenario. The area that the internal mammary artery serves is really close to the heart and so only one end (the distal or far end) is unhooked from where it is going and plumbed into the coronary artery past the coronary blockage. So the blood flows into the mammary arter as normal but is diverted to the heart. The biggest advantage of veins is that in the body, mostly in the peripheries, eg, arms and legs, there are two sets of veins that run in parallel returning blood to the central veins (in the abdomen or chest). Think of varicose veins in the legs, these are removed surgically and the venous drainage of the leg is not harmed because there is another vein running parallel much deeper in the leg that can do the job (as it has only been doing half the job up to now). So the saphenous vein (mentioned in another reply) is in the leg near the surface and, if in good condition, can be used for a graft (bypass artery) as it is long (to get the best bit) and of large diameter so less chance of blockage. The same is true of the superficial veins in the arm (the one you see on the thumb side of your wrist is the arm equivalent to the saphenous vein in the leg). Arteries are not generally taken as, as a rule, they do not run in parallel like the veins. The radial artery is a sort of exception because the radial artery and the ulnar artery (you can just feel it on the little finger side of your wris just a couple of inches from where you feel the radial artery) join up in the palm of you hand in a kind of arch that forms an inverted ‘U’ shape just before the fingers start. If this arch is intact (and in a minority of people it is not) you can use the radial artery because blood can flow round the arch from the ulnar side to supply the bits you have just ‘cut off the blood supply from’. It is important though to check the arch is intact before surgery, a simple but critical test. One downside to the use of veins is that the have one way valves (which is why blood doesn’t just gather in your legs and which have failed in varicose veins). These valves either need to be disrupted (the chosen solution generally but does damage the inside of the vein which can cause clotting) to prevent the arterial flow in their new location on the heart from being stopped, or the vein needs to be turned around, so the valves are open in the direction you want the blood to flow in the heart. Veins to do have their issues though and can become really thickened and fail amongst many other possibilities. In the long term, the grafted vein responds to the higher pressures and becomes structurally more like an artery. TL:DR; Arteries are used but are being used less and less. Veins are used because quite often the occur in parallel pairs in the leg and arm so one can be taken and used as a graft without harm to the arm or leg. Arteries are much narrower and grafts fail more often. Edit; Typos and clarity (yes, clarity)
1 [deleted] [removed]
12 0 DrWYSIWYG There is a lot of bypass surgery that goes on not just the heart. Specifically for the heart the radial artery used to be used but it is being used less and less because the success rate is lower than vein grafts. This is because the diameter of the radial artery is so small that any narrowing (for example at the ends that are sewn into the original artery, or the anastomoses) can cause failure quickly. Veins are generally of larger diameter and have a better latency rate. Another responder to this question mentioned the internal mammary artery being used, which is true but a slightly different scenario. The area that the internal mammary artery serves is really close to the heart and so only one end (the distal or far end) is unhooked from where it is going and plumbed into the coronary artery past the coronary blockage. So the blood flows into the mammary arter as normal but is diverted to the heart. The biggest advantage of veins is that in the body, mostly in the peripheries, eg, arms and legs, there are two sets of veins that run in parallel returning blood to the central veins (in the abdomen or chest). Think of varicose veins in the legs, these are removed surgically and the venous drainage of the leg is not harmed because there is another vein running parallel much deeper in the leg that can do the job (as it has only been doing half the job up to now). So the saphenous vein (mentioned in another reply) is in the leg near the surface and, if in good condition, can be used for a graft (bypass artery) as it is long (to get the best bit) and of large diameter so less chance of blockage. The same is true of the superficial veins in the arm (the one you see on the thumb side of your wrist is the arm equivalent to the saphenous vein in the leg). Arteries are not generally taken as, as a rule, they do not run in parallel like the veins. The radial artery is a sort of exception because the radial artery and the ulnar artery (you can just feel it on the little finger side of your wris just a couple of inches from where you feel the radial artery) join up in the palm of you hand in a kind of arch that forms an inverted ‘U’ shape just before the fingers start. If this arch is intact (and in a minority of people it is not) you can use the radial artery because blood can flow round the arch from the ulnar side to supply the bits you have just ‘cut off the blood supply from’. It is important though to check the arch is intact before surgery, a simple but critical test. One downside to the use of veins is that the have one way valves (which is why blood doesn’t just gather in your legs and which have failed in varicose veins). These valves either need to be disrupted (the chosen solution generally but does damage the inside of the vein which can cause clotting) to prevent the arterial flow in their new location on the heart from being stopped, or the vein needs to be turned around, so the valves are open in the direction you want the blood to flow in the heart. Veins to do have their issues though and can become really thickened and fail amongst many other possibilities. In the long term, the grafted vein responds to the higher pressures and becomes structurally more like an artery. TL:DR; Arteries are used but are being used less and less. Veins are used because quite often the occur in parallel pairs in the leg and arm so one can be taken and used as a graft without harm to the arm or leg. Arteries are much narrower and grafts fail more often. Edit; Typos and clarity (yes, clarity)
1 0 [deleted] [removed]