10 differences between VEINS and ARTERIES

Veins and arteries are blood vessels. But what are the differences between them? In this lesson from a TEACHER we explain the difference between veins and arteries at the level of its structure but also at a functional level because, as you will see, each of the types of blood vessels has a specific structure that allows it to fulfill its role at the functional.

We begin this review of the differences between veins and arteries to attend to the aspects that refer to the structure of these two elements of the circulatory system. The most striking differences are the following:

Structure of the walls

In general, arteries have walls thicker than veins, because they bear greater pressure. The general structure of the tissues that make up blood vessels is the same in veins and arteries. In both cases, the blood vessels are made up of three layers of tissue: tunica adventitia, tunica media, and tunica intima. However, the thickness and composition of the different layers is different in veins and arteries.

instagram story viewer

The main difference between veins and arteries as regards the layers that constitute them is found at the level of the middle tunic. The tunic o middle sheet, which is made up mostly of smooth muscle fibers, is more developed in the arteries than in the veins. In the veins the tunica media is thin with longitudinally arranged smooth muscle fibers.

There are also differences at the level of adventitious tunic (the outermost layer of blood vessels). In both cases, this sheet is made up of connective tissue, which contains collagen fibers and elastic fibers.

In the case of veins the adventitious tunic presents interspersed muscle fibers in connective tissue. While, in the arteries the tunica adventitia does not contain muscle fibers and instead contains fibroblasts (cells that produce elastic fibers for the maintenance of the extracellular matrix).

In the veins have an outer layer or more developed tunica adventitia than the average tunic. The arteries have, on the contrary, a more developed middle lamina than the outermost layer (tunica adventitia).

Due to the characteristics of the layers that form them, veins are less elastic than arteries because they contain fewer muscle and elastic fibers than arteries. The arteries are more resistant, while the veins are much more fragile and brittle.

Internal diameter of vessels

The internal diameter of the veins is greater than that of the arteries, also presenting greater individual variability than the arteries. In lean individuals the veins are thicker than in overweight or obese individuals.

Presence or absence of valves

The veins They present a structure in their internal lamina or tunica intima, which is not present in the arteries. It's all about the calls venous or swallow nest valves, which consist of pocket-shaped pleats. They are oriented towards the heart and prevent blood from traveling in the opposite direction due to the effect of gravity or a decrease in pressure.

Anatomical location

The arteries run deep, intimately linked to the skeleton and the muscular bundles. Much of the veins run parallel to the arteries, in what is known as the deep venous system. But there is also a set of veins that constitute the superficial venous system, located in the subcutaneous fatty tissue, especially on the limbs. Both venous systems are connected to each other through the so-called perforating vessels.

This distribution pattern represents a significant adaptive advantage, since, in the event of an injury, the probability that an artery will be divided is low. In such a way that a hemorrhage in which the blood leaves the body at very high pressures is prevented, producing a very significant loss of blood volume in a very short time, compromising the survival of the individual.

The most common, however, is that the wounds section capillaries or venous conduits in which the blood flows at a lower pressure so that the loss of blood is much less important,

Number

The veins are more numerous than arteries, because in many regions (such as the extremities) each artery is accompanied by two veins.

Individual variability of the distribution pattern

While the distribution pattern is variablein the veinsEspecially in those of the superficial venous system, the arteries are found in the same locations in all individuals.

We end this lesson with the differences between veins and arteries by focusing on the function that each of these parts of our circulatory system perform.

Blood conduction

The direction of blood circulation is opposite in veins and arteries. The arteries are blood vessels that carry blood from the heart to the organs and tissues while in the veins the transported blood follows the opposite way. This is one of the main differences between the two types of blood vessels and explains many of the other differences seen between veins and arteries.

Composition of the blood they carry

The blood carried by veins and arteries also has a different composition. Both in the systemic circulation that irrigates the organs and tissues of the body (except the lungs); as in the pulmonary circulation, where blood travels between the heart to the lungs.

Systemic circulation or greater: The arteries carry oxygenated blood (rich in oxygen) to organs and tissues and veins collect the deoxygenated bloodpoor in oxygen and rich in carbon dioxide produced as a waste substance in cellular respiration).
Pulmonary circulation: in this case the composition of the blood that carries the pulmonary artery from the heart to the lungs, it is deoxygenated blood. Instead the pulmonary veins that carries blood from the lungs to the heart is oxygenated blood.

Blood pressure

The pressure exerted by blood on the walls of blood vessels is very different if it is veins or arteries. In the arteries blood pressure she's very tall, while in the veins and capillaries blood pressure is very low.

Due to the different pressures in the arterial and venous system, it takes less time for blood to travel from the heart to the tissues than to make its way back to the heart.