Blood vessels alter blood flow by vasoconstriction and vasodilation. Chemicals that mediate vasoconstriction include serotonin and norepinephrine among others. Vasoconstriction works by contraction...
Blood enters the right atrium (RA) from the 2 great veins the Superior vena cavae and Inferior vena cavae (SVC and IVC).It then enters the right ventricle (RV) to be pumped at low pressure through...
the oxygenated blood flows from arteries to capillaries and after the exchange of material in capillaries and tissues it goes to vein and veins carries this deoxygenated blood to heart.