13. A 62-year-old African American man presents with exerciseinduced angina. His serum cholesterol is \( 277 \mathrm{mg} / \mathrm{dL} \) (normal < 200), LDL is 157 (normal < 100), HDL is 43 (normal > 35), and triglycerides 170 (normal \( <150 \) ). His body mass index (BMI) is 34 and his coronary risk ratio is 6.84 (normal <5). Cardiac catheterization reveals an occlusion of the left anterior descending and the origin of the right coronary artery. This disease process initially involved which one of the following?
a. Smooth muscle cell proliferation
b. Formation of an intimal plaque
c. Intimal thickening through addition of collagen and elastin
d. Adventitial proliferation of fibroblasts
e. Injury to endothelial cells
14. Which biochemical component of the erythrocyte cell surface is primarily responsible for determining blood type (eg, the A-B-O system).
a. Fatty acid
b. Carbohydrate
c. Nucleic acid
d. Protein
e. Cholesterol
15. What is the approximate life span of a circulating erythrocyte?
a. 8 days
b. 20 days
c. 5 weeks
d. 4 months
e. 1 year
16. Which of the following components increase(s) as a proportion of the respiratory tract wall from trachea to alveoli?
a. Cilia
b. Elastic fibers
c. Smooth muscle
d. Cartilage
e. Goblet cells