Grandparents have always been important. Today, they're even more important. In busy, two-career and single-parent families, an involved grandparent goes a long way to filling a void for children. In extreme situations, the courts have found it's often a grandparent who can reach a troubled teen when no one else can.
Here's how to enlarge your veins and arteries for plasma donation: 1  Heat up your arm. When veins become overheated, they expand, and draw closer to the skin. 2  Hold off on drinking and smoking. Both smoking and drinking alcoholic beverages makes veins and arteries smaller and harder. 3  Hold off on the caffeine.
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. I â¦ n contrast, there is relatively high blood pressure in the arteries, which prevents the need for valves to control backflow.rteries do not need them as the blood in them is being pumped out from the heart under pressure. The pressure it â¦ self prevents backflow. It is interesting to note that veins in the head and upper chest don't have valves either, because blood in them flows under gravity.