Why artery is thick

This reduces the pressure and velocity of blood flow to enable gas and nutrient exchange to occur within the capillaries. Arterioles are innervated and also respond to various circulating hormones and other factors such as pH in order to regulate their caliber, thus modulating the amount of blood flow into the capillary network and tissues. They are surrounded by a thin basal lamina of connective tissue. Structure of a capillary : Capillaries are of small diameter with the vessel wall being a single cell thick.

Capillaries are surrounded by a thin basal lamina of connective tissue. Capillaries form a network through body tissues that connects arterioles and venules and facilitates the exchange of water, oxygen, carbon dioxide, and many other nutrients and waste substances between blood and surrounding tissues.

The thin wall of the capillary and close association with its resident tissue allow for gas and lipophilic molecules to pass through without the need for special transport mechanisms. This allows bidirectional diffusion depending on osmotic gradients. During embryological development, new capillaries are formed by vasculogenesis, the process of blood vessel formation occurring by de novo production of endothelial cells and their formation into vascular tubes.

The term angiogenesis denotes the formation of new capillaries from pre-existing blood vessels. Capillaries do not function independently. The capillary bed is an interwoven network of capillaries that supplies an organ. The more metabolically active the cells, the more capillaries required to supply nutrients and carry away waste products. A capillary bed can consist of two types of vessels: true capillaries, which branch mainly from arterioles and provide exchange between cells and the circulation, and vascular shunts, short vessels that directly connect arterioles and venules at opposite ends of the bed, allowing for bypass.

Capillary beds may control blood flow via autoregulation. This allows an organ to maintain constant flow despite a change in central blood pressure. This is achieved by myogenic response and by tubuloglomerular feedback in the kidney. When blood pressure increases, the arterioles that lead to the capillary bed are stretched and subsequently constrict to counteract the increased tendency for high pressure to increase blood flow.

In the lungs, special mechanisms have been adapted to meet the needs of increased necessity of blood flow during exercise.

When heart rate increases and more blood must flow through the lungs, capillaries are recruited and are distended to make room for increased blood flow while resistance decreases. Privacy Policy. Skip to main content. Cardiovascular System: Blood Vessels. Search for:. Artery Function Arteries are high-pressure blood vessels that carry oxygenated blood away from the heart to all other tissues and organs. Learning Objectives Distinguish the function of the arterial system from that of venous system.

Key Takeaways Key Points Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, with the exception of blood in the pulmonary artery. Arteries typically have a thicker tunica media than veins, containing more smooth muscle cells and elastic tissue.

This allows for modulation of vessel caliber and thus control of blood pressure. The arterial system is the higher-pressure portion of the circulatory system, with pressure varying between the peak pressure during heart contraction systolic pressure and the minimum diastolic pressure between contractions when the heart expands and refills.

The increase in arterial pressure during systole, or ventricular contraction, results in the pulse pressure, an indicator of cardiac function.

Key Terms systolic pressure : The peak arterial pressure during heart contraction. Elastic Arteries An elastic or conducting artery has a large number of collagen and elastin filaments in the tunica media. Learning Objectives Distinguish the elastic artery from the muscular artery. Key Takeaways Key Points Elastic arteries include the largest arteries in the body, those closest to the heart.

They give rise to medium-sized vessels known as muscular, or distributing, arteries. How does blood flow back to the heart from the lower extremities, since it is fighting against gravity? In a heart transplant, if the vagus nerve is not re-transplanted, how is the heart rate kept in check? Is heart disease hereditary? Can a person who subscribes to a very healthy lifestyle suffer a What is the difference between congestive heart failure and coronary artery disease?

See all questions in Circulatory System. Impact of this question views around the world. You can reuse this answer Creative Commons License. So, the answer to the question as to why are arteries thicker than veins is that because arteries have higher blood pressure.

One of the important reasons for the question - why do arteries have thick elastic walls, is that the pressure varies in the arteries during the cardiac cycle. The elasticity and the muscular nature provides the arteries with the flexibility to withstand the extreme pressure and pressure changes during the blood flow.

The pressure is the highest when the heart contracts and lowest when the heart relaxes. The variation in the blood pressure produces a pulse which can be felt in different regions of the body.

This pulse is known as the radial pulse. Apart from the main arteries, the arterioles which carry oxygenated blood to extreme ends of the body also have thick elastic and muscular media. They have a major influence on the local blood pressure and overall blood pressure. The combination of the cardiac output of blood and systemic vascular resistance which refers to collective resistance of blood arterioles are the major deciding factors of arterial blood pressure at any given moment.

Veins, on the other hand, have a smaller Tunica media, comprising less elastic and muscular layer than arteries because veins do not work in a contractile manner like the arteries and are not subject to high systolic pressure. Hence, to the question - Why are arteries thicker than veins? The answer is - Veins are not subject to high blood pressure, unlike the arteries. Similarly, for the question why arteries are thick-walled, it is because the thick elastic and muscular walls of the arteries not only help them sustain the cardiac output pressure but also maintain blood pressure throughout the circulatory system of the body.

The collapse or change in the blood pressure can be catastrophic for the body and hence fatal to the living organism.