It is one of the body's cooling mechanisms, apart from sweating after a period of excercise or a hot day veins come closer to the skin to cool. Nothing to do with blood pressure. The hands, temples, and neck are most noticable.
the veins
No. Arteries, which carry blood away from the heart are usually thick walled and round shaped. Veins on the other hand carry blood to the heart and are slightly more thin walled and more elliptical in shape. Capillaries are the smallest of blood vessels and very thin walled. They carry small amounts of blood relative to veins and arteries.
There are valves in veins to prevent backflow. The blood pressure in veins is relatively low and, particularly in the legs and arms, can tend to pool if allowed to backflow. In contrast, there is relatively high blood pressure in the arteries, which prevents the need for valves to control backflow.
Hand veins are often used as a last resort for obtaining a blood specimen because they are generally smaller and more difficult to access compared to larger veins in the arm, such as the antecubital veins. This can make the procedure more challenging and increase the risk of complications, like hematoma or discomfort for the patient. Additionally, the blood flow in hand veins can be less robust, potentially affecting the quality of the specimen. Therefore, healthcare providers typically prefer to use arm veins first before resorting to the hand veins.
Your veins pop out for many reasons 1. You may be slightly muscular therefore the muscules push the veins up and out 2. Like me your veins may be close to your bone so when you move the bone they pop out 3. There isn't enough blood flow going through them Hope this helps XD
Under a microscope, arteries and veins can be differentiated by their distinct features. Arteries typically have thicker walls and a smaller lumen compared to veins. Arteries also have more elastic fibers in their walls, allowing them to withstand high pressure. Veins, on the other hand, have thinner walls and a larger lumen to accommodate the lower pressure of blood flow. Additionally, veins often have valves to prevent backflow of blood, which arteries do not have. These differences in structure can help identify whether a blood vessel is an artery or a vein when viewed under a microscope.
If your palm veins appear to be filling with black blood, this may be due to a heavy iron content in your blood. Keep in mind that the blood in your veins is purple due to the lack of oxygen and prior to oxidizing in the open air so it may just appear black.
Well Its Mainly left radial and left radial
Arteries have to deal with a large and rapidly changing pressure, to do this without breaking they have to expand. However expanding reduces the blood pressure so it is important for the artery to spring back into shape. Veins don't need to worry about all that, so have thinner walls.
because of chlorophyll in your veins, also depends on blood sugars
But There ARE Veins in your Hands and Feet! When you cut your finger ... it bleeds, so there is a blood supply into your hand. Therefore there must be veins present to carry the spent blood and waste away. They are visible on the back of your hand as faint blue lines. They are most visible under a bright light if you look carefully after drooping your hand down at your side for a few minutes. The same is true about your feet.
Ofcourse not, you don't see them, your fingernails can't bleed and the body doesn't see a need to put nerves in it.