1. Does the pulmonary trunk contain oxygenated blood or deoxygenated blood? Why is it an artery rather than a vein? 2. List the 3 layers of the heart, from superficial to deep. 3. How are cardiac muscle cells connected to one another? 4. How does cardiac muscle resemble skeletal muscle? 5. Suppose a patient has a weakened bicuspid valve (left AV) that does not close properly, a condition called mitral valve prolapse. How does this defect affect the flow of blood in the heart?.