1. Structure: Capillaries are the smallest blood vessels in the body, with a diameter of only 5-10 micrometers. They are made up of a single layer of endothelial cells and are very thin-walled. Veins, on the other hand, are larger blood vessels that carry blood back to the heart. They have thicker walls and contain valves to prevent the backflow of blood.
2. Function: Capillaries are responsible for the exchange of oxygen, nutrients, and waste products between the blood and tissues. They allow for the diffusion of substances in and out of the blood. Veins carry deoxygenated blood back to the heart from the body's tissues.
3. Blood flow: Capillaries have a slow blood flow, allowing for efficient exchange of substances between the blood and tissues. Veins have a slower blood flow compared to arteries, as they are further away from the heart and have lower pressure.
4. Location: Capillaries are found throughout the body, connecting arterioles to venules and allowing for the exchange of substances in tissues. Veins are located closer to the surface of the body and are often visible through the skin.
5. Pressure: Capillaries have the lowest blood pressure in the circulatory system, as they are the smallest blood vessels. Veins have lower blood pressure compared to arteries, as they are further away from the heart and have thinner walls.
6. Oxygenation: Capillaries carry oxygenated blood to tissues and pick up deoxygenated blood from tissues. Veins carry deoxygenated blood back to the heart to be reoxygenated in the lungs.
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Google Gemini AI
Jul 12
Capillaries
- Function: Facilitate the exchange of nutrients, gases, and waste products between the blood and surrounding tissues. - Structure: - Thin, single-layer walls that allow for diffusion. - Endothelial cells, the main cell type, have thin cytoplasm and numerous fenestrations (pores). - Size: - Very small, with a diameter ranging from 5 to 10 micrometers. - Blood flow: - Slow and continuous. - Pressure: - Low, typically around 30 mmHg. - Capillary bed: - Network of intertwined capillaries that form a dense meshwork in tissues.
Veins
- Function: Return blood from tissues back to the heart. - Structure: - Thicker walls than capillaries. - Three layers: tunica intima (innermost), tunica media (middle), and tunica adventitia (outermost). - Contains valves to prevent backflow of blood. - Size: - Variable, ranging from small venules to large veins. - Blood flow: - Slower and less continuous than in arteries. - Pressure: - Gradually decreases from arterioles to venules. - Venous system: - Hierarchy of veins that carry blood back to the heart: venules, small veins, medium veins, large veins, vena cavae.
Additional Differences:
- Muscle: Veins have smooth muscle in their walls, while capillaries do not. - Oxygen saturation: Blood in veins is typically lower in oxygen than blood in capillaries. - Vasodilation and vasoconstriction: Veins can undergo vasodilation and vasoconstriction, which regulates blood flow. Capillaries have limited ability to do so.