B. Vessels 42.8 1. Portal vessels a. From capillary bed to capillary bed without passing through the heart. Classified as vein or artery depending on structure. Forces for movement A. peripheral resistance and blood pressure.
Blood pressure is a measure of hydrostatic pressure of blood against inside of artery wall.
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.