3 types of vessels Arteries ● Blood traveling away from heart ● High pressure = Thick walls ● Larger arteries = Elastic ○ Conduction+propulsion ■ Contract back down to help flow ● Smaller arteries = Muscular ○ Vascular tone ■ Muscular arteries could be contracted ■ Change pressure that exist throughout the system Capillaries ● Between arteries and veins ● Exist in networks ● Single cell thick ● Diffusion happens here ○ Blood gets very close to the other side of the cell ■ Transports and exchange nutrients, oxygen, waste products Veins ● Blood traveling towards the heart ● Low Pressure= Thin walls ● Contains valves when below the heart ○ Promotes blood flow back to heart Other vessel terms Arterioles ● Small retry that regulates blood flow to capillary networks ● Contains sphincters- “resistance vessels” ○ Break on systems ■ If dont need blood supply on certain area, atereols will contract ○ Vasoconstriction + vasodilation Venules ● Drain capillary blood but smallest ones are also a site of diffusions ● Highly distensible ○ “Capacitance vessels” ○ If thick enough, diffusion does not happen anymore ○ Capacitance holds a lot of blood Venous Sinus ● Vein like structure ● Drains venous blood back to the heart or other veins exists in 2 locations: ○ Dural Venous Sinus in the Brains, formed by dura mater ○ Coronary Sinus in the heart Anastomoses ● Union of 2 or more arterial branches supplying the same area ● Collateral blood supply to preserve blood supply to important areas ○ Around the knee base of the brain(circle of Willis) Vessel creates a closed loop Important for collateral circulation of body ● Heart at the center of collateral Varicose Veins ● Valves promote unidirectional flow back toward the heart ○ Valves below the heart ● Muscle contracts and squash vein ○ Pushes blood back towards heart ○ Blood can’t flow backward past valve ● Develops when values are unable to close properly= retrograde flow ○ Typically in superficial veins(limbs) ○ Within Anal canal = hemorrhoids ○ Bleeding esophageal varicose = life threatening (liver disease) ● Varicose happens when vale’s are unable to close properly ○ Retrograde flow Summary ● Vessels form a closed loop through the body center around the hear.to transport blood ○ Heart => Arteries => Arterioles => Capillaries =>Venules => Veins=> Heart ● Artery= Away from heart ● Veins= Towards Heart ● Other Vessel terms ○ Sinus: similar to veins (Cardiac Sinus, Dural Sinus) ○ Anastomoses: 2 arteries\ providing collateral supply ● Reviewed key Vasculature of upper + lower limbs