Julie's grandmother has thickening and hardening of her arteries caused by fatty deposits, cholesterol, and other substances deposited in the inner lining of the arteries. what is this medical term for this condition?

Atherosclerosis.

Explanation:

Atherosclerosis may  be defined as a medical condition the plaque can build up inside the artery of the patient. This disease is asymptomatic and blood flow is not affected at all in this condition.

The arteries of Julie's grandmother get hardened and thickened due to the deposition of cholesterol and fatty acids. These depositions are known as plaques. The medical condition is known as atherosclerosis.