Histology Of Vessels And Lymphatics - Gerdes Flashcards
Arteries and veins have 3 layers which are:
Tunica intima
Tunica media
Tunica adventitia
Tunica intima
Innermost layer of endothelium, basal lamina, and subendothelial layer
Internal elastic membrane of the tunica intima
In the subendothelial layer of the intima. Sheet like layer (lamella) of fenestrated elastic material (internal elastic membrane) that lets substances diffuse And reach cells deep in the vessel wall
Tunica media
Middle layer made of circumferentially arranged layers of smooth muscle cells.
This later is pretty thick and extends from the internal to the external elastic membrane
External elastic membrane
Layer of elastin that separates the tunica media from the tunica adventitia
Tunica Adventitia
Outermost connective tissue later
Contains vasa vasorum (which supplies blood to vessel walls)
Vasa vasorum
Supplies blood to vessel walls
Basic differences between arteries and veins
- Arteries have thicker walls and have relatively thicker TM (tunica media)
- Veins have thinner walls, larger and more collapsed lumen, and TA is relatively more prominent
Arteries diameters
Large artery (elastic artery): > 1 cm dia
Medium artery (muscular artery): 2-10 mm
Small artery: 0.1 – 2 mm
Arteriole: 10-100 μm (histo text, but physiologists say 5-30 μm), smooth muscle layer 1 -2 cells
Capillary: 4-10 μm, only endothelium
Veins Diameters
Postcapillary venule: 10-50 μm, only endothelium and pericytes
Muscular venule: 50-100 μm, smooth muscle layer 1 - 2 cells
Small vein: 0.1 – 1 mm
Medium vein: 1–10mm
Large vein > 1cm