Term
| Characteristic features of the three layers of elastic arteries. Function. |
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Definition
1) Fenestrated IEM that underlies the endothelium and blends with the TM
2) Thickest layer = TM
Elastic and collagen fibers, but no fibroblasts
EEM is the outermost layer of TM
3) Relatively thin TA layer
Vasa vasorum and nervi vascularis present
Conduction tubes that move blood continuously and uniformly away from the heart. |
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Term
| Characteristic features of the layers of muscular, medium or distributing arteries. Function. |
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Definition
1) TI is relatively thin with prominent IEM. Thickness can increase with age.
2) TM has fewer elastic fibers as compared to TM of elastic arteries. Still no fibroblasts.
3) TA is the same thickness or thicker than the TM.
EEM is more diffuse, but still visible.
Distributes blood to the organs and contraction of the thick muscular TM helps maintain BP. |
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Term
| Characteristic features of the three layers of small arteries. |
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Definition
1) IEM may be present in TI.
TI is thin
2) TM has up to 8 layer of smooth muscle
3) Thin TA, poorly defined CT |
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Term
| Characteristic features of the three layers of arterioles. Function. |
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Definition
1) TI similar to small artery, except there is no IEM present.
2) TM has 1-2 layers of SMCs instead of 8 as in small arteries.
3) Similar to small arteries (Thin TA, poorly defined CT).
Controls blood flow to the capillary beds. |
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Term
| Characteristic features of the three layers of capillaries. |
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Definition
1) Just endothelial cells and BL
2) TM is pericytes enclosed in the BL
3) TA is thin wisps of CT. |
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Term
| Characteristic features of postcapillary venules. Functions. |
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Definition
THE THREE INTIMA LAYERS ARE NOT PRESENT.
Endothelial lining with BL. No SMCs, few pericytes. May see valves.
Function: exit site for most of the wandering cells of the CT. Important exchange site. Principal site of action of vasoactive agents such as histamin and serotonin during inflammation and allergic reactions. |
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Term
| Characteristic features of muscular venules |
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Definition
Presence of TM distinguishes muscular venules from postcapillary venules.
Companion to arterioles, larger than arterioles.
TM has 1-2 layers of SMC
TA is very thin. |
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Term
| Characteristic features of small to medium veins. |
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Definition
Lumen is frequently collapsed, tunics less well demarcated.
Companion to muscular arteries and can occur in neurovascular bundles along with nerves.
TA is thickest layer. Contains valves. Patchy IEL. |
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Term
| Characteristic features of the three layers of medium veins. |
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Definition
1) TI has endothelium, BL, thin subendothelial layer of CT, few SMCs. May have thin IEM.
2) TM is much thinner than the TM in medium arteries.
3) TA is thicker than TM and contains collagen and elastic fibers. |
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Term
| Characteristic features of the three layers of large veins. |
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Definition
TI contains endothelium, BL, thin subendothelial layer of CT, few SMCs. Boundary b/t TI and TM often unclear, NO IEM.
2) TM is relatively thin. Contains fibroblasts.
3) TA is thickest layer and contains collagen and elastin, longitudinal SMCs, and fibroblasts. |
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Term
| Characteristic features of lymphatic capillaries. |
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Definition
Tubes of endothelium w/ discontinuous BL.
Anchoring filaments connect the BL to perivascular collagen fibers.
Possess valves to keep flow moving in one direction.
No pump, lymph moves due to compression of lymphatics by adjacent skeletal muscle and thus moves sluggishly. |
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