The aorta receives the full force of blood exiting the heart during ventricular systole. Which of the following statements best describes the adaptive anatomy of the aorta? A) The aorta's tunica media is thick with dense regular connective tissue to withstand the blood's pressure. B) Smooth muscle is relatively thin in the aorta to increase lumen size and systemic blood flow. C) Elastic fibers are extensive in the tunica media of the aorta and dampen the pulse pressure generated by the heart. D) The tunica external of the aorta is nearly absent compared to other vessels.

A & C

Explanation:

Aorta is the biggest artery and channels pumped blood from the left ventricle of the heart to tissues. It, therefore, needs to bear the greatest burden of blood pressure because the left ventricle is thicker than the right ventricle and pumps blood with high pressure so that it reached the tissues with the right hydrostatic pressure to allow blood plasma pass through the capillaries walls into tissue fluid.

The walls of the aorta need to be thick enough and elastic to bear the pressure. This is why the tunica media is thickest it aorta because these elastic fibers provide strength and elasticity to prevent rupturing and smooth muscle cells contract and relax in regulation of this pressure to maintain the right pulse.