Precapillary sphincters: (a) Precapillary sphincters are rings of smooth muscle that regulate the flow of blood through capillaries; they help control the blood flow to where it is needed. (b) Valves in the veins prevent blood from moving backward.
Hereof, why do you have lower blood pressure in capillaries?
In the arterioles blood pressure is lower than in the major arteries. This is because velocity of flow is increased with decrease in diameter and vice versa. This is important as for efficient exchange at the capillary bed pressure and flow need to be much lower.
What affects blood flow through the body?
Many factors can affect blood pressure, such as hormones, stress, exercise, eating, sitting, and standing. Blood flow through the body is regulated by the size of blood vessels, by the action of smooth muscle, by one-way valves, and by the fluid pressure of the blood itself.
How does blood volume affect blood flow?
Changes in blood volume affect arterial pressure by changing cardiac output. An increase in blood volume increases central venous pressure. An increase in right ventricular stroke volume increases pulmonary venous blood flow to the left ventricular, thereby increasing left ventricular preload and stroke volume.