31) The pulmonary arteries carry blood to the

A) heart.

B) lungs.

C) brain.

D) kidneys.

E) pancreas.

32) Which structural feature of cardiac muscle cells enables action potentials to travel rapidly from cell to cell?

A) mitochondria

B) desmosomes

C) gap junctions

D) myofibrils

E) myoglobin

33) The cardiac skeleton of the heart functions to

A) convey blood away from the heart.

B) supply blood to the muscle tissue of the heart.

C) reduce friction between the opposing surfaces of the pericardial sac.

D) stabilize the position of the heart valves.

E) provide for the movement of ions and small molecules.

34) Atrioventricular valves prevent backflow into the

A) ventricles.

B) atria.

C) venae cavae.

D) aorta.

E) pulmonary trunk.

35) The marginal artery branches off the

A) aorta.

B) left coronary artery.

C) interventricular artery.

D) coronary sinus.

E) right coronary artery.

36) Blood from the viscera and the lower limbs is conducted to the heart through which vessel?

A) coronary sinus

B) inferior vena cava

C) pulmonary veins

D) superior vena cava

E) cardiac vein

37) Veins that return blood to the heart are also referred to as ________ vessels.

A) afferent

B) mitral

C) valvular

D) efferent

E) pulmonary

38) Cardiac muscle cells have abundant reserves of myoglobin, which function in ________.

A) removing waste products

B) storing iron

C) removing carbon dioxide

D) storing oxygen

E) the shortening of individual sarcomeres

39) The right and left coronary arteries originate at the ________.

A) aortic sinuses

B) coronary sinus

C) pulmonary trunk

D) marginal artery

E) fossa ovalis

40) If valve function deteriorates such that the heart cannot maintain adequate circulatory flow, symptoms of ________ appear.

A) mitral valve prolapse

B) carditis

C) coronary artery disease

D) rheumatic fever

E) valvular heart disease