📸 Wiley Plus Chapter 20 Part 1

The visceral layer of the serous pericardium:

is the outer layer of the heart

The thickest wall in the heart due to its increased work load is the:

left ventricle

What is the correct pathway of blood starting at the right atrium?

right atrium, right ventricle, pulmonary trunk, pulmonary veins, left atrium, left ventricle, aorta

A skeletal muscle may undergo tetanus but cardiac muscle cannot.

True

Comparatively, which phase is the longest during an action potential in a ventricular contractile fiber?

Refractory

What is occurring during isovolumetric contraction?

All four valves are closed

The walls of the atria are thicker because the atria receive blood under pressure.

False

The walls of the ventricles are thicker because the ventricles pump blood under higher pressure over greater distances.

True

The wall of the right ventricle is thinner than that of the left ventricle because the right side of the heart pumps blood a shorter distance at lower pressure.

True

Although the right side of the heart has a smaller workload, the right and left ventricle simultaneously eject the same amount of blood.

True

Prolapse of the atrioventricular valves is prevented by

contraction of the papillary muscles

The semilunar valves open when pressure in the right and left ventricles exceeds that in the pulmonary trunk and aorta, respectively.

True

The intercalated discs seen in cardiac myocytes

1. have desmosomes which help to hold the muscle fibers together.

2. have gap junctions which allow action potentials to conduct from one muscle fiber to the next

3. are the result of actin/myosin overlap.

1 and 2 are correct

Which represents the correct flow of excitation through the cardiac conduction system?

SA node, AV node, bundle of His, right and left bundle branches, Purkinje fibers

Which of the following places the phases of the cardiac cycle in correct order?

atrial contraction, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, ventricular filling, atrial contraction

The plateau seen in action potentials recorded from ventricular fibers is due to inflow of Ca+2.

True

Isovolumetric contraction and isovolumetric relaxation both occur when all four valves are closed.

True

Purpose of the structure indicated is to: (right auricle?)

slightly increase the capacity of the atrium (see diagram)

What occurs after the QRS phase of the ECG?

the ventricles contract

The pericardium consists of a fibrous and serous layer. The visceral layer of the serous pericardium may be referred to as the epicardium.

True

The right atrium receives blood from the superior and inferior vena cava and the coronary sinus while the left atrium receives blood from the 4 pulmonary veins.

True

Autorhythmic fibers are self-excitable

True

Autorhythmic fibers: are pacemakers

True

Autorhythmic Fibers: Form the conduction system of the heart

True

The left ventricular pressure must be greater than the aortic pressure during ventricular ejection so that blood will move out through the pulmonary arteries.

False

The membrane that surrounds and protects the heart is called the

pericardium

Which of the following is used to reduce friction between the layers of membranes surrounding the heart?

pericardial fluid

Which layer of the heart wall consists of cardiac muscle tissue?

myocardium

Contraction of the ventricles of the heart leads to blood moving directly

into arteries

Which of the following chambers of the heart contains deoxygenated blood?

right atrium and right ventricle

Cardiac muscle fibers are electrically connected to neighboring fibers by

gap junctions

Which network of specialized cardiac muscle fibers provides a path for each cycle of cardiac excitation to progress through the heart?

cardiac conduction system

Which term refers to the period of time during a cardiac cycle when contraction of a chamber occurs and pressure within the chamber rises?

systole

Which wave in an electrocardiogram represents repolarization of the ventricles?

T wave

Identify the structure indicated in this diagram

pulmonary valve

The structure indicated is the:

endocardium (C)