Elastic nature of vessel walls spring back producing peripheral resistance a. which prevents a drop of blood pressure to 0 between beats of the heart. Hence will never be 0 unless you are dead. Muscles compress the veins and valves keep blood flowing in the proper direction. During the time the pressure is low in the chest cavity, the major veins entering the heart swell, lower the pressure inside and encouraging blood flow to low pressure. Law of continuity a. volume of fluid flowing through a pipe must be the same at any point along the pipe.
Veins narrow the pipe and speed up the flow back to the heart.
Capillary exchange - A. Transfer of substances between blood and the interstitial fluid exceeds that predicted by diffusion alone 1.