Blood vessels function consist of arteries, capillaries, and veins. The vascular networks deliver blood to all tissues in a targeted and regulated manner. The arteries and veins consist of three layers of tissue. The thick outer layer of the vessel (tunica adventitia or tunica external) is made of connective tissue.



The middle layer (the tunica medium) is thicker and contains more systolic tissue in the arteries than in the veins. It includes connective tissue, circularly arranged elastic fibers, and smooth muscle cells.



The internal layer (tunica intima) is the lean layer, includes of a single endothelial layer supported by the subendothelial layer. Capillaries consist of a single layer of endothelium and associated connective tissue.



Blood vessels function

Blood vessels function fetch nutrients and oxygen throughout the body and help in gas exchange. Vessels are parts of the systemic and pulmonary circulation that distributes blood throughout the body. There are three main types of blood vessels.



The arteries that carry blood from the heart, branching to smaller arterioles throughout the body and eventually forming a network of capillaries. Capillaries, in turn, merge into veins, and then into larger veins responsible for restoring blood to the heart. The arteries and veins consist of three different layers, while much smaller capillaries consist of one layer.



Tunica Intima

The internal layer (tunica intima) is the thick layer formed from a single continuous layer of endothelial cells and a supported subendothelial layer of connective tissue and support cells. In smaller arterioles or veins, this subendothelial layer consists of a single layer of cells, but it can be much thicker in larger vessels such as the aorta.



The tunica intima is surrounded by a lean membrane composed of elastic fibers running parallel to the vessel. Capillaries contain only of a thick layer of the endothelium of cells with an associated thin layer of connective tissue.



Tunica Media

 This layer is much thicker in the arteries than in the veins. The fiber composition is also different. The veins consist of small elastic fibers and function as a control of the caliber of the arteries. The key step in maintaining blood pressure.



Tunica Externa

The outermost layer is the outer tunic or roadside tunica, made entirely of connective fibers and surrounded by an external flexible blade that acts to anchor the vessels with the surrounding tissues. The outside tunica is usually thicker in the veins to prevent the collapse of the blood vessel and provide protection against damage because the veins can be superficially located.



Valve function

In blood vessels function, the major structural difference between arteries and veins is the presence of valves. In the arteries, blood pump under pressure from the heart, so the backflow cannot occur.


However, the passage through the capillary network causes a decrease in blood pressure, which means that the flow of blood in the veins is possible. To resist this, the veins incorporate numerous one-way valves that prevent backflow.



Key points (TAKEAWAYS)

The fundamental and pulmonary circulation system effectively supplies oxygen to body tissues and removes metabolic products, such as carbon dioxide. Arterial blood (with the exception of the pulmonary artery) is highly saturated with oxygen and supplies oxygen to the tissues of the body. Venous blood (except the pulmonary vein) is deoxygenated and returns to the heart to pump it into the lungs for re-irradiation.



The immune cells shift in the circulatory system and are capable of rapidly penetrating through the walls of blood vessels to sites of injury or infection. Blood vessels can grow or reduce the flow of blood near the surface of the body, increasing or decreasing the amount of heat lost as a means of regulating body temperature.



blood vessels function Key terms

In blood vessels function key terms, thermoregulation: sustaining a constant internal temperature of the body regardless of the ambient temperature
Blood plays many critical roles in the body: supplying nutrients and chemicals to tissues, removing waste and maintaining homeostasis and health. The circulatory system carries blood through the body to perform these activities, assisted by a vast network of blood vessels.




Gas transfer

The circulatory system can divide into two parts, systemic and pulmonary. In the structural circulatory system, highly oxidized blood (95-100%)  pump from the left ventricle and into the body arteries.


After arriving the capillary network, gas exchange between tissue and blood may occur, facilitated by the narrow walls of the capillaries. The capillaries merge into veins, transferring deoxygenated blood (~ 75%) back to the right atrium of the heart at the end of the systemic circulation.



A much smaller lung system reoxygenates the blood and facilitates the removal of carbon dioxide. After the heart leaves the right ventricle, blood passes through the pulmonary artery. The only artery in the body including deoxygenated blood and into the capillary network of the lungs.



The direct connection of thin-walled vesicles with equally thin-walled capillaries allows for quick release of carbon dioxide and oxygen absorption. After quite the lungs through the pulmonary vein, the only vein that carries oxygenated blood. The blood enters the left atrium. This completes the pulmonary circulation system.


Additional features & blood vessels function

In blood vessels function, blood vessels beside facilitating rapid distribution and efficient transport of agents such as glucose, amino acids or lipids to tissues and removal of waste products for processing elsewhere, such as lactic acid into the liver or urea into the kidneys.


In other, the blood vessels are an absolute network for the surveillance and distribution of the immune system. Lots of white blood cells circulate around the body, sensing infection or injury.