Search results
Results From The WOW.Com Content Network
The small veins merge to feed as tributaries into medium-sized veins. The medium veins feed into the large veins which include the internal jugular, and renal veins, and the venae cavae that carry the blood directly into the heart. [13] The venae cavae enter the right atrium of the heart from above and below.
Post-capillary venules are the smallest of the veins with a diameter of between 10 and 30 micrometres (μm). When the post-capillary venules increase in diameter to 50μm they can incorporate smooth muscle and are known as muscular venules. [1] Veins contain approximately 70% of total blood volume, while about 25% is contained in the venules. [2]
In anatomy, the venae cavae (/ ˈ v iː n i ˈ k eɪ v i /; [1] sg.: vena cava / ˈ v iː n ə ˈ k eɪ v ə /; from Latin 'hollow veins') [2] are two large veins (great vessels) that return deoxygenated blood from the body into the heart. In humans they are the superior vena cava and the inferior vena cava, and both empty into the right atrium ...
Oxygen-poor blood enters the right side of the heart through two large veins. Oxygen-rich blood from the lungs enters through the pulmonary veins on the left side of the heart into the aorta and then reaches the rest of the body. The capillaries are responsible for allowing the blood to receive oxygen through tiny air sacs in the lungs.
The capillaries connect to venules, and the blood then travels back through the network of veins to the venae cavae into the right heart. The micro-circulation — the arterioles, capillaries, and venules —constitutes most of the area of the vascular system and is the site of the transfer of O 2 , glucose , and enzyme substrates into the cells.
Coronary circulation is the circulation of blood in the arteries and veins that supply the heart muscle (myocardium). Coronary arteries supply oxygenated blood to the heart muscle. Cardiac veins then drain away the blood after it has been deoxygenated.
Blood flows out of the capillaries into the venules, which have little smooth muscle and are 10-200 μm. The blood flows from the venules into the veins. Metarterioles connect arterioles and capillaries. A tributary to the venules is known as a thoroughfare channel. [citation needed]
Blood flows from the heart through arteries, which branch and narrow into arterioles, and then branch further into capillaries where nutrients and wastes are exchanged. The capillaries then join and widen to become venules, which in turn widen and converge to become veins, which then return blood back to the heart through the venae cavae.