In what direction does blood flow through the heart? a) from ventricles to atria b) from a region of high pressure to a region of low pressure c) from a region of high oxygen content to a region of low oxygen content d) from a region of high volume to a region of low volume

b) from a region of high pressure to a region of low pressure

Explanation:

Blood flow is measured in blood volume per unit time. It is the movement of blood through an organ, tissue or vessel. It is initiated when ventricles in heart contract leading to its ejection at high pressure. Major arteries receive this blood and they further transport it at high pressure to smaller arteries, arterioles and capillaries. Hence arteries have thick walls to withstand this pressure. The pressure decreases when blood reaches to veins hence their walls are not that thick.  Hence, blood flows from a region of high pressure to a region of low pressure.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?