Medically reviewed by Gerhard Whitworth, R.N. — composed by Scott Frothingham — to update on April 12, 2018

Arteries space blood vessels responsible for transferring oxygen-rich blood away from the heart to the body. Veins are blood vessels that carry blood short in oxygen indigenous the body earlier to the heart because that reoxygenation.

Arteries and veins space two that the body’s main form of blood vessels. These vessels are channels that distribution blood come the body. They’re part of 2 closed solution of tubes that begin and also end in ~ the heart. These solution of tubes are either:

Systemic. The systemic vessels room arteries that lug oxygen-rich blood native the heart’s left ventricle to the tissues in all parts of the body. They then return oxygen-poor blood through the veins ago to the heart’s best atrium.

There are three types of arteries. Each type is composed of 3 coats: outer, middle, and also inner.

You are watching: Why do veins have valves but arteries do not

Elastic arteries are also called conducting arteries or conduit arteries. They have a thick center layer for this reason they deserve to stretch in response to each pulse that the heart.Muscular (distributing) arteries are medium-sized. They draw blood from elastic arteries and branch into resistance vessels. These vessels include tiny arteries and also arterioles. Arterioles room the smallest department of arteries that transfer blood away from the heart. They direct blood into the capillary networks.

There room four species of veins:

Deep veins are located within muscle tissue. They have a equivalent artery nearby.Systemic veins are situated throughout the human body from the legs as much as the neck, consisting of the arms and trunk. They deliver deoxygenated blood earlier to the heart.

Use this interaction 3-D diagram to explore an artery.

Use this interactive 3-D chart to explore a vein.

The walls of veins and also arteries are both made up of three layers:

Outer. Tunica adventitia (tunica externa) is the outer layer that a blood vessel, consisting of arteries and also veins. It’s mainly composed that collagen and also elastic fibers. These fibers enable the veins and also arteries come stretch a minimal amount. They stretch sufficient to be versatile while keeping stability under the press of blood flow. Middle. The middle layer that the wall surfaces of arteries and veins is dubbed the tunica media. It’s make of smooth muscle and also elastic fibers. This layer is more thick in arteries and thinner in veins.Inner. The inner great of the blood vessel wall surface is called tunica intima. This class is made of elastic fiber and also collagen. That consistency varies based upon the type of blood vessel.

Unlike arteries, veins contain valves. Veins require valves to store the blood flowing towards the heart. Theses valves are specifically important in the legs and also arms. They fight heaviness to protect against the backflow the blood.

Arteries don’t require valves due to the fact that the press from the heart keeps the blood flowing with them in one direction.

The cardiovascular device is a closed device of vessels called arteries, veins, and capillaries. They’re all linked to a muscular pump referred to as the heart. The cardiovascular system keeps a continuous and regulated movement that blood that delivers nutrients and also oxygen to every cell in the body. That does this through countless miles the capillaries in between the arteries and the veins.

See more: Number Of Valence Electrons In Calcium (Ca), Calcium Valence Electrons

Capillaries. Capillaries room the smallest and most numerous of the blood vessels. They connect between the arteries (which bring blood away from the heart) and the veins (which return blood to the heart). The primary role of capillaries is the trading of materials, like oxygen, between the blood and also tissue cells.

Nutrients and oxygen are yielded to every cabinet in her body v a circulatory system. The heart pumps oxygenated blood to your cells v arteries. The pumps oxygen-depleted blood away from your cells v veins.


Medically the review by Gerhard Whitworth, R.N. — created by Scott Frothingham — to update on April 12, 2018