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Course: MCAT > Unit 3

Lesson 1: Chemical and physical sciences practice passage questions

Coronary heart disease and blood pressure


Coronary heart disease affects 13 millions Americans, and is the leading cause of death both in America and worldwide. Coronary heart disease is caused by a build up of plaque in the arteries that supply blood to the heart. When the flow of blood to the heart is restricted or blocked, the heart can get damaged due to a lack of oxygen. This is commonly referred to as a “heart attack.” Further, if a large piece of plaque buildup gets dislodged from an artery wall, it can get stuck in other arteries throughout the body including the brain.
Consider a person who has a cylindrically shaped piece of plaque that is blocking an artery of radius R as shown in the diagram provided. The blood pressure (gauge pressure) on the right side of the plaque is PR. This particular piece of plaque will break free if the net force on the plaque exerted by blood pressure is greater than F.
Figure 1. The section of the patient's artery blocked with plaque.
How tall would a column of water (density ρw) have to be in order for the bottom of the water column to have the same pressure as the blood on the right side of the plaque?
Choose 1 answer: