1) Which type of vessels, arteries, or veins, has more muscle fibers? What is the functional significance of this?
2) In general, we have no conscious control over smooth muscle or cardiac muscle function, whereas we can consciously control to some extent all skeletal muscles. Can you consciously control your breathing? What does this tell you about the muscle type of diaphragm?
3) What is a portal system? What organs does the hepatic portal system connect in adults? What is the purpose of this system?