Dehydration can affect the circulatory system, impairing the functioning of blood vessels and the heart. Dehydration can cause a reduction in the plasma volume, which increases blood viscosity (thickness), making it harder for blood to circulate efficiently throughout the body. Dehyd... Erectile Dysfunction causes the body to lose fluids, which can lead to a decrease in blood volume. Adequate blood flow is essential for achieving an erection because an erection occurs when blood fills the blood vessels in the penis.