1. Veins are essential components of the circulatory system.
• It came from the Latin word “vena”.
• The circulatory system is composed of the Heart, blood and blood vessels.
• It is categorized into four main type; pulmonary, systemic superficial and deep veins.
• Veins, together with arteries and capillaries transport blood by a complex network through various parts of the body to the heart.
2. Veins are flaccid blood vessels.
• Unlike arteries whose walls are composed of smooth muscle cells with extracellular collagen venous walls are less elastic than arterial wall.
• This explains why veins are predisposed and more prone in inflammation, swelling and even tumor growth.
3. Veins are the port for blood transfusion.
• Blood products are introduced slowly into the veins during transfusion for the restoration of blood volume.
• Veins hold approximately about two thirds of the circulating blood.
• It size can range from one millimeter to 1.5 centimeters in diameter.
4. Veins have one-way valves.
• This venous structure allows blood to flow in one direction and to keep the blood moving throughout the circulation and preventing reverse or back flow of blood.
5. Veins are used for drawing blood for laboratory test.
• Lumen of veins have three concentric layers:
o Tunica intima is a single layer of endothelial cells which is the thinnest layer of the vein.
o Tunica media is a layer of smooth muscles which provide structural support and give the elastic property of the vein.
o Tunica adventitia is the strong outermost coat of a vein which is the layer of connective tissues and autonomic nerves.
• Its thinner walls and larger diameters make it favorable for taking blood samples for analysis.
• Venous blood pressure is lower hence blood seeping is less likely to occur during venipuncture.
• Donated blood is also drawn from veins.
6. Veins carry deoxygenated blood.
• Two exceptions are pulmonary veins and umbilical veins.
• There are two main large veins that serve as pathway of blood coming from lower and upper part of the body, the inferior and superior vena cava respectively.
• It is an artery which carries oxygenated blood.
7. Blood in the veins are dark red in color.
• It was never blue in color as what you see superficially visible underneath your skin.
• It appears to be bluish due to absorption of low frequency light by the subcutaneous fats wherein blue wavelength penetrates the skin thus reflected as blue and perceived by the viewer.
• Venous blood has a higher concentration of urea and waste product of cellular metabolism
• On the other hand, arterial blood is bright red in color as the blood is highly oxygenated and rich in hemoglobin.
8. Veins may swell as a result of venous valve dysfunction.
• Veins may get enlarged as a result of too much extra pressure and valves not working properly allowing the blood to back up into the vein.
• These are called varicose veins which are usually seen under the skin commonly in the legs.
9. Veins may collapse from reduced blood flow.
• There are quite a few circulation disorders affecting blood vessels including veins.
• These disorders are secondary to disruptions of blood flow as a result of narrowing vessels, malformations or collapse.
• High risks factors for venous varicosities are obesity, pregnancy and aging.
10. Wondering why body builders have bulging veins all over their bodies?
• A muscleman (or musclewoman) has their veins proudly standing out.
• This is due to a leaner body physique which means less fats covers their subcutaneous veins, thus, veins are pushed out by harder muscles closer to the skin.