The circulatory system is responsible for transporting oxygen and nutrients around the body.
Describe three structural features of capillaries that adapt them for the rapid and efficient exchange of substances with surrounding tissues.
Coronary heart disease (CHD) is a condition where fatty deposits build up inside the coronary arteries, narrowing their lumen. Explain how this structural change reduces the rate of blood flow to the heart muscle, and how the resulting lower oxygen delivery affects the heart muscle cells' respiration and performance during physical exertion.