Before that, support for the elderly wasn't a federal concern - it mostly fell to states, towns and, of course, families. The program is based on contributions that workers make into the system. While you're employed, you pay into Social Security; you receive benefits later on, when it's your turn to retire. Contributions take the form of the Federal Insurance Contributions Act (FICA) taxes that are withheld from most paychecks.
The blood vessels are part of the circulatory system and function to transport blood throughout the body. The most important types, arteries and veins, carry blood away from or towards the heart, respectively. All blood vessels have the same basic structure. The inner lining is the endothelium and is surrounded by subendothelial connective tissue. Around this there is a layer of vascular smooth muscle, which is highly developed in arteries. Finally, there is a further layer of connective tissue known as the adventitia, which contains nerves that supply the muscular layer, as well as nutrient capillaries in the larger blood vessels.
Known as the body parts that are important to blood circulation, blood vessels have three kinds, namely the veins, the capillaries as well as the arteries. The veins are responsible for transporting blood to the heart from the capillaries.