CARLA 13

Which of the following is true regarding cardiac muscle? 1) Neither summation or tetany can occur 2) Both summation and tetany can occur 3) Summation, but not tetany, can occur 4) Tetany, but not summation, can occur 5) None of these are true

1) Neither summation or tetany can occur

Which of the following is longer? 1) the refractory period of cardiac muscle 2) the refractory period of skeletal muscle

1) the refractory period of cardiac muscle

In which situation would the stroke volume be the greatest? 1) when venous return is increased 2) when venous return is decreased 3) when calcium channel blockers are present 4) when the difference between the end diastolic volume and the systolic volume is small 5) when the force of contraction is decreased

1) when venous return is increased

Each of the following factors will increase cardiac output except one. Identify the exception 1) increased venous return 2) increased parasympathetic stimulation 3) increased force of ventricular contraction 4) increased heart rate 5) increased sympathetic stimulation

2) increased parasympathetic stimulation

The following are various component of the conducting system of the heart 1) Purkinje cells 2) AV bundle 3) AV node 4) SA node 5) Bundle branches the sequence in which an action potential would move through the system is

4,3,2,5,1

Depolarization of the ventricles is represented on the electrocardiogram by the

QRS complex

The pacemaker cells of the heart are located in the___

SA node

The P wave of the ECG corresponds to

atrial depolarization

The heart is innervated by

both parasympathetic and sympathetic nerves

Under conditions of hypercalcemia

cardiac muscles become extremely excitable

The function of an atrium is to

collect blood

The left and right pulmonary veins carry blood to the___

heart

Blood returning from the systemic circuit first enters the

right atrium

The volume of blood ejected from each ventricle during a contraction is called the___

stroke volume

The cardioacceleratory center in the medulla oblongata activates ____ neurons

sympathetic

As a result of the long refractory period, cardiac muscle cannot exhibit

tetany

The first heart sound is heard when

the AV valves close

The left ventricle pumps blood to

the systemic circuit

According to Starling's Law of the heart, the cardiac output is directly related to...

the venous return

Relaxation of the ventricles is called

ventricular diastole