Final answer:
There are three primary blood vessels: arteries carry oxygen-rich blood away from the heart, veins return the blood to the heart, and capillaries exchange substances between blood and tissues. Arteries have muscular walls to handle pressure, veins have thinner walls, and capillaries have very thin walls for exchange. Blood consists of plasma, red blood cells, white blood cells, and platelets.
Step-by-step explanation:
Types of Blood Vessels and Their Functions
The cardiovascular system is composed of various types of blood vessels that each perform distinct roles in circulating blood throughout the body. There are three primary types of blood vessels:
Veins: These blood vessels return oxygen-depleted blood back to the heart. The two largest veins in the body are the superior vena cava and the inferior vena cava.
Capillaries: These are tiny blood vessels that connect arteries to veins and facilitate the exchange of oxygen, carbon dioxide, and other nutrients and wastes between blood and the tissues of the body.
Blood flow through arteries is normally under higher pressure than in veins, and this pressure difference, along with one-way valves in veins, assists in returning blood to the heart.
The arterial walls are more muscular and elastic to handle the high pressure of the blood pumped by the heart, while veins have thinner walls and larger lumen to accommodate the low-pressure blood flow. Capillaries, in contrast, have very thin walls to allow for the exchange of substances.
Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and it is typically expressed in millimeters of mercury (mm Hg). Normal blood pressure is considered to be around 120/80 mm Hg.
Composition of BloodBlood consists of plasma, red blood cells, white blood cells, and platelets. Red blood cells transport oxygen, white blood cells defend the body against infection, platelets help with blood clotting, and plasma is the liquid component that carries these cells along with nutrients, hormones, and waste products.