Histology: Circulatory System Flashcards Preview

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Flashcards in Histology: Circulatory System Deck (15)

What are the 3 layers of vessels?

Tunica intima

Tunica media

Tunica adventitia


What are the components of the tunica intima?

• Endothelium

• Subendothelium

• Internal elastic lamina (IEL) in arteries 


What are the components of the tunica media?

• Smooth muscle layer
• External elastic lamina (EEL) in arteries 


What are the components of the tunica adventitia?

• Connective tissue and fibroblasts
• Longitudinal smooth muscle in veins
• Vasovasorum in large vessels 


What is a unique structure found only in veins?



What vessel part is very large in large arteries?

Tunica media


What is the major cell type that dominates medium arteries?

Smooth muscle (AKA muscular artery)


What is the difference between small and medium arteries?

Generally have same structure as medium artery but have a smaller diameter and no external elastic lamina. The tunica media also has fewer layers of smooth muscle cells. 


What is the difference between the arterioles and other blood vessels?

Only two layers of smooth muscle cells. Internal elastic lamina, external elastic lamina, and subendothelial layers usually absent. 


Continuous, Fenestrated and Discontinuous Capillaries

Continuous - no holes at all

Fenestrated - holes on the endothelium

Discontinuous - holes on the endothelium AND basal lamina


What layer generally dominates in veins?

Tunica adventitia which is at least as wide as the media, and often even wider. 


What layer are the valves in veins formed from?

Tunica media


Where are the vasa vasorum found?

Tunica adventitia


What are the differences in the lumen of arteries and veins?

Arteries are smaller and rounder with prominent internal elastic lamina while veins are larger and flatter


What are some of the features of the lymphatic vessels?

  • Have large lumens and relatively thin walls
  • Single layer of endothelium
  • Connective tissue outer layer with few smooth muscle cells
  • Also have valves 

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