What are the blood vessels?Blood vessels are a network of powerful tubes that carry blood from place to place throughout the body. Functionally, blood vessels divide arteries, veins and capillaries, including differences in the building. We will look at both arteries, veins and capillaries and mention little about the arteries and major veinsBlood vessel buildingVascular General building applies to most vessels with differences between arteries, veins and capillaries. Most vessels consist of the following layers:The inner layer, scientifically called the Tunica Intima, is the lining of the vessel cavity consisting of only one layer of lining cells.
The middle layer, scientifically called the tunica media ( Tunica Media ): a class consisting mostly of smooth muscles and elastic fibers. This layer is the most varied between the various vessels in terms of fish, building, and the amount of elastic fibers.The outer layer, scientifically called tunica adventitia : an outer layer of connective tissue and envelops the blood vessel.ArteriesArteries ( Arteries ), a collection of the word Artery ( Artery ) is the blood vessels that carry oxygen-rich blood and nutrients from the heart to all parts of the body, called arterial blood carried arteries arterial blood. The blood from the heart is subjected to severe pressure following the contraction of the strong heart muscle, so the arteries must bear this pressure. The arteries are characterized by strong, solid, solid vessels. With arterial branching, pressure on each artery decreases gradually. The arteries have the three distinct layers of each blood vessel.
The middle layer is characterized by its thickness and smooth muscle. In many cases, the arteries in the body are connected to each other, allowing the flow of blood to the organs in the event of blockage of some arteries. We note the presence of several grades of the arteries and there are differences between them: the large arteries, the arteries, medium and small arteries.It has a lot of flexible fibers in the middle layer, the first arteries that carry blood from the heart such as the aorta , subclavian artery and carotid artery.
The flexibility of the large arteries allows for the pressure coming from the heart. This elasticity enables it to expand when it receives blood, reducing pressure and preventing damage to its wall. It is also important to maintain proper blood pressure.Medium ArteriesThe difference lies in size, and most of its inner layer consists of smooth muscles.
The large number of muscles in the wall of the arterial arteries gives them the ability to contract, thus controlling the amount of blood that takes place in different parts of the body. It is important to control the amount of blood according to the process performed by the body. For example, after food, the middle arteries of the gastrointestinal tract expand, while the lateral arteries of the limbs contract, making the arterial blood most of the digestive system. The opposite is true when doing physical exertion. An example of these arteries is the femoral artery and the brachial artery.Small ArteriesThey also include Arterioles , a group of small, narrow, and musculoskeletal arteries. Small arteries are very important in two things: the first is to control the flow of blood to the capillaries, and the second is to determine blood pressure.
This is done by the degree of smooth muscle contraction in the wall of the small arteries. The lower the muscles, the smaller the diameter of the artery, the higher the blood pressure and the less blood flow to the capillaries. There are no special names for small arteries, and can only be seen microscopic.The veinsVeins , a collection of the word Vein , are blood vessels that restore blood from all parts of the body to the heart, specifically the right atrium. The function of veins is to transport oxygen-poor blood, rich in carbon dioxide and waste from all parts of the body to the right heart, to replace gases.
Oxygen-poor blood is the one that gives veins a dark blue color that is oblique to the violet. There is one difference in the function of veins, in pulmonary veins that carry oxygen rich blood from the lungs to the left heart. Because the veins return blood to the heart, the pressure in the veins is very low so the veins are accurate vessels and the middle layer is accurate compared to the arteries. Often, the veins do not pump blood but make it only by the effect of pressure difference between them and the arteries – which drives blood from the arteries to the veins, including the heart. Compared to arteries, the veins have a wider diameter, a thinner wall and less thick, making the volume of veins sufficient for a large amount of blood. Therefore, most blood (80%) is present in the veins at each time point, and only 20% in the veins.
As with the arteries, the veins are connected.In the limbs of the body are two ways to restore blood to the heart, against the forces of gravity that draw the blood down while the flow up to the heart. The first method is the venous valves (see below). The second method is the use of the leg muscles that press the veins as if they are being pumped, thus pushing the blood towards the heart.The veins as many degrees as with the arteries:Venules : The smaller ones, which drain venous blood directly from the capillaries and then accumulate to form medium-sized veins. Small veins often form venous networks.Medium Veins : Are the veins of intravenous and venous networks, often accompanied by medium-sized arteries in their path.
In the extremities, where the force of gravity prevents blood from flowing towards the heart, the veins in the medium venous valves (Venous Valves ) that allow blood to rise towards the heart and prevent it from drawing towards the ground. An example of the medial veins ( Cephalic Vein ) in the upper limbs,Basilic Vein and Saphenous Vein .Large Veins : Large in size, wide in diameter, with many smooth muscles in the middle layer. Most notably the inferior vena cava and superior vena cava.Blood capillariesIn order for the cells of the body organs to get oxygen and nutrients that are blocked by the arteries, the oxygen and food get out of the blood vessels that transport to the cells.Capillaries are the means to achieve this. Blood capillaries are tiny and very small vessels that connect the arterial side and the venous side of the bloodstream.
The capillaries consist of only one layer, the inner layer ( Tunica Intima ), which allows the exchange of food and gases around the cells.Blood capillaries are organized in complex and interconnected networks. These networks are called capillary beds. Blood enters the capillaries from the small arteries, and drains through the veins. The pressure inside the capillaries and inside the arteries, which stimulates the blood, nutrients and oxygen to get out of the capillaries, allowing the replacement of gases and capture of nutrients. In the venous side, where the pressure is reduced, the capillaries recover carbon dioxide and food waste and drain the blood to the veins.
In some areas of the body there are no capillaries, and there is direct contact between the arteries and veins. An example is the skin and the fingers of the hand and the man.Arteriovenolar Anastomoses is called intravenous arterial contact. In other parts of the body, the blood passes through two capillaries before returning to the veins.
For example, the portal venous system in the digestive system, which purifies blood from digestive tract waste before entering the liver.Major arteriesAortaIs the main artery in the body is the first artery out of the heart and carries blood oxygen-rich arterial and branch of the arteries that in turn provide the body with arterial blood.The aorta is divided into several sections:Ascending Aorta : A diameter of 2.5 cm and starts in the aortic valve opening. The ascending aortic artery has only two branches – the right coronary artery and the left coronary artery, which supply the heart with arterial blood. The aorta is called an ascending aorta because of its ascending path at this stage.
Aortic Arch : A reversal in the aortic path when it reaches the level of the second rib almost. The bow moves to the top and back and slightly to the left, and then bends to pass to the left of the esophagus and trachea. The arch is divided into three arteries: the common left cochlear artery, the left subcellular artery, and the vertical humerus.Descending Aorta : also called Thoracic Aorta , which is a continuation of the curve of the aortic arch and takes a straight path to the bottom. The descending aorta continues down to the bottom of the abdomen and there is a branch of the right and left iliac arteries that extend the pelvis, genitals and legs.Aries of the aortic archBrachiocephalic Trunk : The first branch of the aortic arch, in turn, branches into two branches:Right carotid artery, which extends the neck and head.
Right Subclavian Artery : Provides the right hand with arterial blood.Left Common Carotid Artery : The second branch of the aortic arch, beginning behind the chest bone. Ascends towards the neck, is located in front of the left undercellular artery, extending neck and head as well.
Left Subclavian Artery : The third and last branch of the aortic arch, located behind the left common carotid artery, ascends towards the left hand to deliver it with blood.Major veinsIs the group of veins in the chest. ( Brachiocephalic Vein ), each of which is a subclavian Vein ( intracellular vein ) – the hand – and internal jugular Vein – which removes venous blood from the head and neck. At the right first leg, the left and right vertical left veins merge and form the superior vena cava, the main vein that enters the right atrium from the upper side. The upper vena cava returns venous blood to the heart of all organs above the diaphragm, except the heart and lungs. The lower vena cava ( Inferior Vena Cava ) is the result of the convergence of the main veins coming from all organs under the diaphragm, and enters the right atrium of the heart from the lower side.
Reference : . https://opentextbc.ca/anatomyandphysiology/chapter/20-1-structure-and-function-of-blood-vessels/