| Lab 7 Cardiovascular System: 1) Index 2) Introduction 3) Things to identify 4) Muscular Arteries ... 5) Arterioles 6) Elastic Arteries 7) Capillaries 8) Medium Sized Veins 9) Large Veins 10)Venules .. 11) Lymphatic Vessel 12) Heart 13) Practical |
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Medium
Sized Veins
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# 73 - Artery, human, c.s., h-e, 1.5 mm # 76 - Artery, vein, nerve, monkey, h-e, 1.5 mm If needed: # 212 - Artery and vein, rabbit, h-e, 1.5 mm # 168 - Ductus deferens, human, 1.5 mm |
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Study the relative thickness of the tunics of medium sized veins and compare these structures with those of the comparable muscular artery. Relate the larger caliber and thinner wall of the vein to its function. Both the intima and media of veins are thinner than that of arteries with that corresponding diameter. You should be able to find examples of small arteries and veins adjacent to each other. Some sections may show a valve in one of the larger veins. If your specimen has such an example, please show it to your colleagues. References: Ross, p. 324, Fig. 3 Gartner, p. 159, Fig. 1 -2 p. 315, Fig. 12.11 (diagram) Wheater, p. 151, Fig. 8.19 |
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This is a slide of a Medium Sized Vein, (yellow arrow). Why do we know it is a vein? Because it has that flimsy look to it, unlike arteries that have a rigid structure enabling it to maintain it's circular shape. The blue arrows are pointing at the bulging nuclei of the endothelial cells lining the lumen. Notice that the tunica media of a vein this size is a lot smaller than it would be in an artery of about the same size. The white arrows are pointing to the smooth muscle cells in the tunica media. There are only a couple layers. Veins do not have a large musculature associated with them because they act mainly as a reservoir for blood, and have more expansive properties, than contractile ones. The venous system is also a much less pressure system than is the artery system. That is why the vein is flimsy, it doesn't need all that support like the arteries to with stand the higher pressures. Yellow arrow - Medium Sized Vein Blue arrows - Endothelial Cell bulging nuclei White arrow - Smooth Muscle Cells of Tunica Media |
Medium Sized Vein |
