M1 Quiz #2

Cardiac muscle is not prone to fatigue because it makes little use of anaerobic fermentation or the oxygen debt mechanism. A. True B. False

A. True

The __________ performs the work of the heart. A. myocardium B. fibrous skeleton C. endocardium D. pericardial cavity E. epicardium

A. myocardium

Place the vessels in order through which blood would pass beginning with blood entering the systemic circuit after exiting the heart:

1.Conducting arteries 2.Distributing arteries 3.Resistance arteries 4. Arterioles 5.Capillaries 6.Post-capillary venules 7. Muscular venules 8.Medium veins 9. Venous sinuses 10.Large veins

The long plateau in the action potential observed in cardiomyocytes is probably related with __________ staying longer in the cytosol. A. Ca2+ B. K+ C. Na+ D. Cl- E. Na+, K+, and Ca2+

A. Ca2+

Desmosomes form channels that allow each cardiomyocyte to electrically stimulate its neighbors. A.True B.False

B. False

The pulmonary circuit is supplied by both the right and the left sides of the heart. A. True B. False

B. False

Opening and closing of the heart valves is caused by _________. A. valves contracting and relaxing B. pressure gradients C. osmotic gradients D. breathing E. gravity

B. Pressure gradients

The plateau in the action potential of cardiac muscle results from the action of __________ A. K+ inflow B. slow Ca2+ channels C. K+ outflow D. fast Ca2+ channels E. Na+ inflow

B. slow Ca2+ channels

Which of the following is a feature shared by cardiac muscle and skeletal muscle? A. Intercalated discs B. Dependence upon nervous stimulation C. Communication via electrical (gap) junctions D. Autorhythmicity E. Muscle fiber striations

E. Muscle fiber striations

Alternative routes of blood supply are called __________. A. thoroughfare channels B. preferred channels C. metarterioles D. capillary beds E. anastomoses

E. anastomoses

Blood usually passes through one network of capillaries from the time it leaves the heart until the time it returns, but there are exceptions, notably the __________. A. portal systems B. vaso vasorum and anastomoses C. vasa vasorum D. anastomoses E. portal systems and anastomoses

E. portal systems and anastomoses