Ch 19 Heart

Calcium channels in the nodal cells function to: a. cause deplorization and initiate the cardiac action potential. b. assure excess calcium can leave the cell. c. bring the cell quickly to its resting membrane potential. d. sustain contraction of the cell.

A

Preload is a measure of: a. heart chamber volume prior to contraction. b. contraction rate in cardiac muscles. c. reduced filling during exercise. d. autonomic nervous system stimulation of the heart.

A

Venous blood draining the heart wall (coronary sinus) enters the right atrium through the a. coronary sinus. b. inferior vena cava. c. pulmonary veins. d. superior vena cava.

A

Action potentials are spread rapidly between cardiac muscle cells by a. sarcomeres. b. intercalated discs. c. chemical neurotransmitters. d. the fibrous skeleton.

B

The pericardial cavity is located between the: a. fibrous pericardium and the parietal layer of the serous pericardium b. parietal and visceral layers of the serous pericardium. c. visceral layer of the serous pericardium and the epicardium. d. myocardium and the visceral layer of the serous pericardium.

B

Which of the following is the correct circulatory sequence for blood to pass through part of the heart? a. right atrium --> left AV valve --> right ventricle --> pulmonary semilunar valve b. right atrium --> right AV valve --> right ventricle --> pulmonary semilunar valve c. left atrium --> right AV valve --> left ventricle --> aortic semilunar valve d. left atrium --> left AV valve --> left ventricle --> pulmonary semilunar valve

B

Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium? a. to assure rapid conduction speed of the action potential. b. to pull on AV valve cusps to prevent backflow. c. to assure blood will surge toward the semilunar valves. d. to assure coordinated contraction of the ventricular myocardium.

B

All of the following occur when the ventricles contract except: a. the AV valves close. b. blood is ejected into the aorta. c. the semilunar valves open. d. blood from the pulmonary trunk enters the atria

D

How is blood prevented from backflowing from the pulmonary trunck into the right ventricle? a. closing of the right AV valves b. opening of the pulmonary semilunar valve c. contraction of the right atrium d. closing of the pulmonary semilunar valve

D

What occurs during the atrial reflex? a. Atria slow their filling rate. b. there is a decrease in heart rate due to an increase in blood pressure. c. the SA node rhythm decreases. d. an increase in heart rate occurs in response to an increase in blood volume within the atria.

D