yes
Two valves
all veins contain valves
They would be considered incompetent valves because they are not working properly. You need all the vein valves to work properly for maximum functioning.
A cross section of a vein shows a thinner wall than that of the artery, and shows one-way valves. A cross section of an artery shows a thicker, more muscular wall and no valves.
The facial vein has no valveshttp://en.wikipedia.org/wiki/Facial_vein
A varicose vein is a distended vein where the valves are unable to close properly. This can lead to thromboses, which are blood clots and can make the veins hard, bumpy, and painful.
yes
Yes, because there is more pressure in the artery than in the vein so the artery has to be big enough to hold the pressure that's inside it.
one having semilunar cusps, i.e., the aortic and pulmonary valves; sometimes used to designate the semilunar cusps composing these valve
There are a number of structures that help with the one way flow of blood through the veins. These include valves in the vein lumen, and the assistance of surrounding skeletal muscle.
To identify a valve in a vein, look for small, bulging structures along the vein's length, often appearing as localized constrictions or flaps. These valves are typically found at intervals and can be palpated or observed using ultrasound imaging. In some cases, the flow of blood can also be assessed, as valves prevent backflow, allowing blood to move only in one direction toward the heart.
Venous insufficiency is a condition in which blood pools in the vein because the valves have become incompetent.