There is no major changes to blood with age, but there is a reduction of red bone marrow. This means that there is a diminished capacity for blood cell formation in the elderly.
In the absence of heart disease the heart remains essentially the same size, or diminishes slightly in size. The is a reduction in the number and size of cardiac muscle cells with aging and an increase in fibrous tissue.
Blood vessels reduce in elasticity with age. This is due to a reduced elastic fiber content in the wall of the arteries.