packet 4 Flashcards
These muscular, elastic vessels carry blood under pressure from the heart. They branch many times before they become arterioles
artery
Microscopic, thin-walled but still muscular vessels that regulate blood flow into the capillaries
arterioles
Single layer of epithelial cells that allow exchange of fluids, gasses, and nutrients in tissues. They then pass on to venuoles
capillaries
Thin-walled vessels that intersect others to begin returning blood to the heart. Eventually they merge to become larger veins
venuoles
Similar structure to arteries, but much thinner walls, wider diameter, and less elastic; role?
veins
tunica interna. Very thin inner lining in contact with blood.
inner layer
three layers of inner layer
squamous cell epithelium
epithelial basement membrane
internal elastic lamina
“endothelium” that lines the entire circulatory system. Cells help in regulation of vessel contraction, protection of cells, mediating capillary permeability and preventing permeability elsewhere.
squamous cell epithelium
Tough acellular layer that anchors endothelium to connective tissues. Additional barrier to diffusion.
epithelial basement membrane
Porous, elastic fibers
internal elastic lamine
*thin, tough, flexible layer to contain blood and mediate exchange with surrounding tissues.
inner layer (tunica internal)
tunica media. Muscular, elastic layer that varies considerably in thickness between the vessel types. Composition: smooth muscle, elastic fibers
middle layer
encircle vessel to regulate diameter, essential to direct blood flow and modify blood pressure.
smooth muscle cells
provide flexible support within the muscular layer.
elastic fiber
essential to direct blood flow and provide structural strength and flexibility.
middle layer (tunica media)