The systemic circuit: blood is delievering o and nutrients and is picking up the waste products to deliver them to the kidneys (or lungs if it is co ) Involves the organs and muscles: when linear flow rate is reduced, is due to the cross-sectional area increasing ( in radius = flow rate) Microcirculatory beds: the systemic arteries ultimately deliver blood to networks of microscopically tiny blood vessels in all the systemic organs & tissues, consists of 3 types of vessels. Venules: right ventricle then increases pressure to 1. 9kpa for passage through lungs. Low pressure: have a system of one-way valves (helps ensure blood flows continuously to heart, much thinner-walled than arteries, blood flows from microcirculatory beds back to the heart through a series of veins of ing diameter. Fluctuations indicated heart beats: at veins pressure will be boosted slightly to go through lungs; will then be boosted a lot to go through left ventricle to go back through body.