Large Vein
Made of three layers--not distinct, thin walled:
1. Tunica intima-innermost layer, contains:
- Endothelium--flat squamous cells lines the lumen.
Subendothelial connective tissue and internal elastic lamina not well defined.
2. Tunica media contains large amount of collagen fibers:
- Few smooth muscle fibers, elastic fibers present.
3. Tunica adventitia-outer most layer, thickest layer:
- Connective tissue with collagen fibers.
Contains longitudinally running smooth muscle fibers,
Example: Inferior vena cava, superior vena cava.
Medium Sized / Muscular Artery
Identification Points
1. Three layers of blood vessel-tunica intima, tunica media, tunica adventitia (externa).
2. Tunica media is thickest with more smooth muscle fibers.
3. Internal elastic lamina is prominent.
Made of three layers:
1. Tunica intima is the innermost layer, contains:
Endothelium--flat squamous cells fines the lumen.
Subendothelial connective tissue.
Internal elastic lamina made of elastic fibers in the form of fenestrated membrane. It is wavy and prominent.
2. Tunica media--thickest layer:
Smooth muscle fibers are predominant, circularly/spirally arranged.
Contraction of smooth
muscles reduces the luminal diameter. They also give rise to the elastic and collagen fibers. Help in repair of damaged endothelial cells.
Few elastic fibers present.
Outer external elastic lamina present.
3. Tunica adventitia-outer most layer:
- Contains connective tissue with collagen and elastic fibers.
Example: Radial, ulnar, popliteal arteries.
Large / Elastic Artery
1. Tunica intima is the innermost layer, contains:
Endothelium-flat squamous cells lines the lumen.
Subendothelial connective tissue.
- Internal elastic lamina made of elastic fibers in the form of fenestrated membrane---not prominent.
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2. Tunica media-thickest layer:
Elasticfibers are prominent in the form of concentric fenestrated lamellae. Hence, internal elastic lamina is not prominent. Help in recoil of the artery after distention.
Few smooth muscles fibers are also present.
Outer external elastic lamina present.
3. Tunica adventitia:
Outer most connective tissue layer with predominant collagen fibers. Also contains vasa vasorum (blood vessels that supply the walls of large blood vessels).
Example: Aorta, brachiocephalic trunk, common carotid, subclavian and common iliac arteries.