20. The couples, arteries and veins
An artery has blood stream full of oxygen, and a vein has blood stream with low oxygen. Arteries and veins go in pairs for any anatomical structure and share names. For example, an artery and a vein for a kidney go together, which are called the renal artery and renal vein.
During dissection, we get rid of veins and only spare the arteries. This is to get a clear view of arteries. In anatomy labs, less important things are sacrificed to make important things stand out. To lose something in order to earn something is common in this world.
Arteries have higher blood pressure than veins as arteries have to send blood throughout the entire body. Going against gravity to reach the brain is not an easy job. Therefore, a ruptured artery with high blood pressure will cause massive bleeding. A ruptured vein will cause slow leakage of blood, but a ruptured artery will gush out blood like fountain. This is the reason why arteries are placed deeper than veins in our bodies.
In hospitals, intravenous injections are common. Injections are made into superficial veins to get blood samples or to administer medications. Everyone can see superficial veins on their arms. However, superficial arteries are not visible. It would be dangerous for arteries to be placed in thin subcutaneous tissues.
It is easier to see superficial veins in a man who works out. Enlarged muscles require more blood supply. Also, thinned subcutaneous tissue makes the veins more visible. A talented nurse will inject a needle into the nearly invisible superficial vein in an infant. An expert like this could inject a needle with eyes closed into the superficial vein of a muscleman.
Arteries are safely enclosed by muscles. However, there are several arteries that are not surrounded by muscles and we can feel the pulse of these arteries. Pulse is felt not because an artery has high blood pressure, but because an artery is not surrounded by muscles.
A male med student makes use of this knowledge on his girlfriend. "When measuring pulse, we usually use radial artery on the side of the thumb. We could also use ulnar artery on the side of the fifth finger. Then as we go up, we could feel the brachial artery between the biceps." Finally, "we can feel the subclavian artery right on top of the clavicle. I have to focus so stay still".
The male student can't resist the temptation to feel the superficial veins. He puts his finger on top of the back of his girlfriend's hand, and pushes back and forth with his finger. "If I push my finger towards your body, blood quickly fills the superficial veins. But if I push my finger away from your body, blood fails to fill the superficial veins. It is a sign that blood flows in the direction towards the body." While doing so, the male student figures out how useful anatomy is.