Answer:
Capillaries
Explanation:
In the circulatory sytem, the blood flow depends greatly on the blood vessels. As the blood flows through a vessel, it exerts a force against the walls of that vessel, and the measure of that force per unit area is defined as the blood pressure.
Like every other fluid, blood tends to flow from a high pressure region to a low pressure one. This means that when the blood ejects directly from the heart, in first instance it flows through the arteries, wich are the vessels with the highest pressure, then this arteries split into arterioles, where a drop in pressure occurs due to the smaller diameter that these vessels have, which at the same times generates more resistance to the blood flow and therefore a decrease in velocity and pressure. Then the arterioles split into the capillaries, which are the tiniest of all the blood vessels, meaning that they have the smallest diameter, therefore, a drop in pressure and velocity occurs once again when the blood reaches the capillaries. This decrease in velocity is very important because it allows for the exchange of nutrients and waste products between the capillaries and the cells.
