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Venules and veins. Blood flows from the capillaries into very small veins called venules, then into the veins that lead back to the heart. Veins have much thinner walls than do arteries, largely because the pressure in veins is so much lower. Veins can widen (dilate) as the amount of fluid in them increases.
- Quick Facts
Blood travels from the heart in arteries, which branch into...
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The heart and blood vessels constitute the cardiovascular...
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Abnormally high blood pressure during systole with normal...
- Overview of Blood
The body contains about 5 to 6 quarts (about 5 liters) of...
- Varicose Veins
Arteries carry blood with oxygen and nutrients away from the...
- Quick Facts
Figure 18.2.2 18.2. 2: Structure of Blood Vessels. (a) Arteries and (b) veins share the same general features, but the walls of arteries are much thicker because of the higher pressure of the blood that flows through them. (c) A micrograph shows a similarly sized artery and vein.
- Shared Structures. Different types of blood vessels vary slightly in their structures, but they share the same general features. Arteries and arterioles have thicker walls than veins and venules because they are closer to the heart and receive blood that is surging at a far greater pressure (Figure \(\PageIndex{2}\)).
- Arteries. An artery is a blood vessel that conducts blood away from the heart. All arteries have relatively thick walls that can withstand the high pressure of blood ejected from the heart.
- Arterioles. An arteriole is a very small artery that leads to a capillary. Arterioles have the same three tunics as the larger vessels, but the thickness of each is greatly diminished.
- Capillaries. A capillary is a microscopic channel that supplies blood to the tissues, a process called perfusion. Exchange of gases and other substances occurs between the blood in capillaries and the surrounding cells and their tissue fluid (interstitial fluid).
Figure 6.6.2. Structure of blood vessels. (a) Arteries and (b) veins share the same general features, but the walls of arteries are much thicker because of the higher pressure of the blood that flows through them. (c) A micrograph shows the relative differences in thickness. LM × 160.
- Anna Chruścik, Kate Kauter, Louisa Windus, Eliza Whiteside
- 2021
- Arteries
- Veins
- Capillaries
- Walls of Arteries and Veins
- Capillary Walls
- Attributions
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are defined as blood vessels that carry blood away from the heart. Blood flows through arteries largely because it is under pressure from the pumping action of the heart. It should be noted that coronary arteries, which supply heart muscle cells with blood, travel towardthe heart, but not as part of the blood flow that travels through the chambers ...
are defined as blood vessels that carry blood toward the heart. Blood traveling through veins is not under pressure from the beating heart. It gets help moving along by the squeezing action of skeletal muscles, for example, when you walk or breathe. It is also prevented from flowing backward by valves in the larger veins, as illustrated in Figure 1...
are the smallest blood vessels in the cardiovascular system. They are so small that only one red blood cell at a time can squeeze through a capillary, and then only if the red blood cell deforms. Capillaries connect arterioles and venules, as shown in Figure 14.4.7. Capillaries generally form a branching network of vessels, called a capillary bed, ...
The walls of both arteries and veins have three layers: the tunica intima, tunica media, and tunica adventitia. You can see the three layers for an artery in the Figure 14.4.9. 1. The is the inner layer of arteries and veins. It is also the thinnest layer, consisting of a single layer of endothelial cells surrounded by a thin layer of connective ti...
The walls of capillaries consist of little more than a single layer of epithelial cells. Being just one cell thick, the walls are well-suited for the exchange of substances between the blood inside them and the cells of surrounding tissues. Substances including water, oxygen, glucose, and other nutrients, as well as waste products (such as carbon d...
Figure 14.4.1 bodybuilding_PNG24 from pngimg.com is used under a CC BY-NC 4.0(https://creativecommons.org/licenses/by-nc/4.0/) license. Figure 14.4.2 Arterial_System_en.svg by Mariana Ruiz Villarreal [LadyofHats] on Wikimedia Commons is in the public domain(https://en.wikipedia.org/wiki/Public_domain). Figure 14.4.3 Skeletal_Muscle_Vein_Pump by Ope...
Betts, J. G., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., DeSaix, P. (2013, June 19). Figure 20.6Capillary bed [digital image]. In Anatomy and Physiology(Section 20.1). OpenStax. https://openstax.org/books/anatomy-and-physiology/pages/20-1-structure-and-function-of-blood-vessels Betts, J. G., Yo...
- Christine Miller
- 2020
The function of blood vessels is to deliver blood to the organs and tissues in your body. The blood supplies them with the oxygen and nutrients they need to function. Blood vessels also carry waste products and carbon dioxide away from your organs and tissues. Each type of blood vessel serves a different function:
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Blood vessels are hollow tubes like pipes that carry blood through your body. The blood delivers oxygen and nutrients to all parts of your body and removes waste products, such as carbon dioxide. Arteries have thick walls lined with muscle. Arteries need to be strong because blood pressure is highest in the arteries.
