its structure and function. The number of neurons, or brain cells, declines in some parts of the brain. The brain shrinks as it pulls away from the skull, and the amount of space between brain and skull doubles from age 20 to 70.
             Also, there is a reduction in the flow of blood within the brain, which also uses less oxygen and glucose. The reduced flow of blood in the brain is partly due to reduction in the capacity of the heart to pump blood throughout the circulatory system.
             Due to hardening and shrinking of blood vessels in the body, the heart is forced to work harder, and it is typically unable to compensate fully. This results in decreased maximum blood flow to and from the heart, increased recovery time after each contraction, and other strengths (Timirias, 1978). The blood vessels become less elastic and some become clogged resulting in fewer capillaries, delivering blood to the entire body. In old age, t
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