Section 19.2: Cardiac Muscle and Electrical Activity - Questions

What is the primary function of myocardial conducting cells?

a) To contract and pump blood

b) To initiate and propagate action potentials

c) To store calcium ions

d) To provide structural support

b) To initiate and propagate action potentials

Which structure in the heart is known as the pacemaker?

a) Atrioventricular node

b) Sinoatrial node

c) Purkinje fibers

d) Bundle of His

b) Sinoatrial node

What is the role of calcium ions in cardiac muscle contraction?

a) They initiate the electrical impulse

b) They provide energy for contraction

c) They prolong the plateau phase

d) They prevent tetany

c) They prolong the plateau phase

What does the QRS complex in an ECG represent?

a) Atrial depolarization

b) Ventricular depolarization

c) Ventricular repolarization

d) Atrial repolarization

b) Ventricular depolarization

What is the function of intercalated discs in cardiac muscle?

a) To store calcium ions

b) To synchronize contraction

c) To initiate electrical impulses

d) To provide energy

b) To synchronize contraction

The sinoatrial node is located in the ___ wall of the right atrium.

superior and posterior

Cardiac muscle cells have a long ___ period to prevent tetany.

refractory

The ___ wave in an ECG represents atrial depolarization.

P

Describe the role of the atrioventricular node in the cardiac conduction system.

The atrioventricular node delays the electrical impulse to allow the atria to contract and pump blood into the ventricles before the ventricles contract.

What is the significance of the plateau phase in cardiac contractile cells?

The plateau phase prolongs the action potential, ensuring a long refractory period that prevents tetany and allows the heart to fill with blood.