What is the Difference Between Aorta and Vena Cava?

The aorta and vena cava are two main types of blood vessels attached to the heart, and they have distinct functions and structures:

• Function: The aorta carries oxygenated blood from the heart to the rest of the body, while the vena cava carries deoxygenated blood from the body back to the heart.
• Structure: The aorta is the largest artery in the body, with a thicker wall compared to the vena cava, which has a thinner wall. The vena cava is the largest vein in the body.
• Orientation of Elastin and Collagen: In the vena cava, elastin fibers show an obvious longitudinal orientation, whereas medial and adventitial collagen fibers are predominantly circumferential. In contrast, the aorta has a more complex structure with varying orientations of elastin and collagen.
• Wall Thickness: The aorta has a significantly thicker wall (1.32 ± 0.09 mm) compared to the vena cava (0.83 ± 0.06 mm).
• Content of Elastin and Collagen: The aorta has significantly less collagen (35.78 ± 7.92 μg/mg) but more elastin (22.39 ± 1.06 μg/mg) than the vena cava, which has significantly more collagen (83.96 ± 7.92 μg/mg) than elastin.
• Mechanical Properties: The aorta and vena cava have different mechanical properties, with the aorta showing a stiffer circumference than the vena cava. Much greater anisotropy is observed in the vena cava, with its average circumference stretch being 1.06 ± 0.01 and average longitudinal stretch being 1.30 ± 0.06 at 200 kPa. In contrast, the average aorta circumference and longitudinal stretch range from 1.19 ± 0.01 to 1.22 ± 0.01 at 200 kPa.

Comparative Table: Aorta vs Vena Cava

Here is a table comparing the differences between the aorta and vena cava: