Ch 19, Part 2 - Lecture Objectives and Study Guide

The general structure of cardiac muscle includes (a)  

• Striations and intercalated discs
• Smooth muscle fibers
• Lack of nuclei
• Voluntary control

Cardiac muscle cells meet their energy needs by:

• Using anaerobic respiration

• Relying on glycolysis

• Utilizing fatty acids and oxygen

• Storing large amounts of glycogen

The components of the heart's conduction system include (a)  

• Sinoatrial node, Atrioventricular n
• Aorta, Pulmonary artery, Left ventr
• Tricuspid valve, Mitral valve, Aort
• Superior vena cava, Inferior vena c

The role of parasympathetic and sympathetic innervation of the heart is to:

• Increase heart rate and force of contraction

• Decrease heart rate and force of contraction

• Regulate heart rate and force of contraction

• Have no effect on heart rate and force of contraction

What is the membrane potential of SA nodal cells at rest, and how do they depolarize spontaneously?

• The membrane potential is -60 mV, and they depolarize due to the funny current.

• The membrane potential is -70 mV, and they depolarize due to sodium influx.

• The membrane potential is -80 mV, and they depolarize due to calcium influx.

• The membrane potential is -90 mV, and they depolarize due to potassium efflux.

Autorhythmicity and pacemaker potential in the heart are defined as:

• The ability of the heart to generate its own rhythm and the gradual depolarization leading to an action potential.

• The heart's response to external stimuli and the rapid repolarization phase.

• The synchronization of heartbeats with external pacemakers and the plateau phase of the action potential.

• The heart's ability to contract without any electrical activity and the refractory period.

What is the first step for SA nodal cells to spontaneously depolarize?

• Opening of sodium channels

• Closure of potassium channels

• Opening of calcium channels

• Closure of calcium channels

The spread of the action potential through the heart's conduction system is best described by which of the following?

• It starts at the SA node, travels through the atria, to the AV node, down the bundle of His, and through the Purkinje fibers.

• It begins at the AV node, moves to the SA node, then to the bundle of His, and finally through the Purkinje fibers.

• It originates in the Purkinje fibers, moves to the bundle of His, then to the AV node, and ends at the SA node.

• It starts at the bundle of His, travels to the Purkinje fibers, then to the AV node, and finally to the SA node.

The sarcolemma of cardiac muscle cells at rest is:

• Polarized

• Depolarized

• Hyperpolarized

• Neutral

Match the following membrane potentials with their corresponding states.

• Resting potential of a typical neuron

• -70 mV

• Neutral potential

• -90 mV

• Action potential peak

• 0 mV

• Resting potential of the sarcolemma

• +30 mV