ANATOMY

Detailed explanation-1: -Pressure is a measure of the force that the blood exerts against the vessel walls as it moves the blood through the vessels. Like all fluids, blood flows from a high pressure area to a region with lower pressure. Blood flows in the same direction as the decreasing pressure gradient: arteries to capillaries to veins.

Detailed explanation-2: -As blood moves through the capillaries, the oxygen and other nutrients move out into the cells, and waste matter from the cells moves into the capillaries. As the blood leaves the capillaries, it moves through the veins, which become larger and larger to carry the blood back to the heart.

Detailed explanation-3: -Blood pressure in the arteries is much higher than in the veins, in part due to receiving blood from the heart after contraction, but also due to their contractile capacity.

Detailed explanation-4: -Each time the heart beats (contracts and relaxes), pressure is created inside the arteries. The pressure is greatest when blood is pumped out of the heart into the arteries. When the heart relaxes between beats (blood is not moving out of the heart), the pressure falls in the arteries.

Detailed explanation-5: -As the blood vessel splits from the small arteries and into the arterioles, there is a drop in blood pressure. This drop occurs because there is an increased ratio of surface area to volume, which means that the blood is in contact with more blood vessel surface area.