Histology Testbank: Cardiovascular System 1a

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
Which layer of the heart is composed of cardiac muscle?
a. Epicardium
b. Pericardium
c. Myocardium
d. Endocardium
e. Endomysium

Answer: c

The heart consists of three layers: epicardium, myocardium and endocardium.

The epicardium is the outer layer of the heart, containing the blood vessels and nerves which supply the heart.

The myocardium is the muscular layer of the heart.

The endocardium is the inner layer of the heart. The innermost portion of the endocardium is composed of endothelium, a simple squamous epithelium.

The pericardium is the connective tissue sac that the heart sits in.

Endomysium is the connective tissue covering of an individual muscle cell.

2. Where is the myocardium the thickest? a. Right atria b. Left atria c. Right ventricle d. Left ventricle e. Both right and left ventricle

Answer: d

The myocardium is the middle layer of the heart. It is thickest in the left ventricle, since the left ventricle is responsible for pumping blood throughout the systemic circulation.

3.
What is the connective tissue sac surrounding the heart?
a. Epicardium
b. Pericardium
c. Myocardium
d. Endocardium
e. Endomysium

Answer: b

The heart consists of three layers: epicardium, myocardium and endocardium.

The epicardium is the outer layer of the heart, containing the blood vessels and nerves which supply the heart.

The myocardium is the muscular layer of the heart.

The endocardium is the inner layer of the heart. The innermost portion of the endocardium is composed of endothelium, a simple squamous epithelium.

The pericardium is the connective tissue sac that the heart sits in.

Endomysium is the connective tissue covering of an individual muscle cell.

4.
What is the connective tissue called which surrounds an individual cardiac
muscle fiber?
a. Epicardium
b. Pericardium
c. Myocardium
d. Endocardium
e. Endomysium

Answer: e

The heart consists of three layers: epicardium, myocardium and endocardium.

The epicardium is the outer layer of the heart, containing the blood vessels and nerves which supply the heart.

The myocardium is the muscular layer of the heart.

The endocardium is the inner layer of the heart. The innermost portion of the endocardium is composed of endothelium, a simple squamous epithelium.

The pericardium is the connective tissue sac that the heart sits in.

Endomysium is the connective tissue covering of an individual muscle cell.

5.
What is the pacemaker of the heart?
a. Sinoatrial node
b. Atrioventricular node
c. Bundle of His
d. Right bundle branch
e. Purkinje fiber

Answer: a

A cardiac impulse is transmitted through a specific pathway of modified cardiac tissue within the heart. The pacemaker of the heart is the sinoatrial node (SA node). The impulse then goes to the AV node. It goes through the ventricles via the bundle of His. The bundle of His is also called the atrioventricular bundle. This divides into right and left bundle branches. From there the impulse is transmitted into Purkinje fibers.

6.
Which of the following is not true regarding the endocardium?
a. The endocardium contains abundant adipose tissue
b. The endocardium is layered
c. The endocardium contains blood vessels
d. The endocardium contains smooth muscle
e. The endocardium is lined by endothelium

Answer: a

The epicardium contains abundant adipose tissue, not the endocardium.

The endocardium is the inner layer of the heart. The layers of the heart being: endocardium, myocardium, and epicardium. The endocardium itself is layered. The innermost layer of the endocardium is lined by endothelium. The middle layer of the endocardium is connective tissue and smooth muscle. The outer layer of the endocardium is the subendocardial layer. The endocardium contains blood vessels.

7.
What is the atrioventricular bundle?
a. Sinoatrial node
b. Atrioventricular node
c. Bundle of His
d. Right bundle branch
e. Purkinje fiber

Answer: c

A cardiac impulse is transmitted through a specific pathway of modified cardiac tissue within the heart. The pacemaker of the heart is the sinoatrial node (SA node). The impulse then goes to the AV node. It goes through the ventricles via the bundle of His. The bundle of His is also called the atrioventricular bundle. This divides into right and left bundle branches. From there the impulse is transmitted into Purkinje fibers.

8.
Where is endothelium located?
a. Epicardium
b. Pericardium
c. Myocardium
d. Endocardium
e. Endomysium

Answer: d

The heart consists of three layers: epicardium, myocardium and endocardium.

The epicardium is the outer layer of the heart, containing the blood vessels and nerves which supply the heart.

The myocardium is the muscular layer of the heart.

The endocardium is the inner layer of the heart. The innermost portion of the endocardium is composed of endothelium, a simple squamous epithelium.

The pericardium is the connective tissue sac that the heart sits in.

Endomysium is the connective tissue covering of an individual muscle cell.

. "Pulling on heartstrings" refers to strong feelings of love or sympathy pulling one's conscience. What anatomical structure is it a reference to? a. Sinoatrial node b. Bundle of His c. Right bundle branch d. Purkinje fiber e. Chordae tendinae

Answer: e

The chordae tendinae are threadlike structures between the papillary muscles to the valves of the heart.

A cardiac impulse is transmitted through a specific pathway of modified cardiac tissue within the heart. The pacemaker of the heart is the sinoatrial node (SA node). The impulse then goes to the AV node. It goes through the ventricles via the bundle of His. The bundle of His is also called the atrioventricular bundle. This divides into right and left bundle branches. From there the impulse is transmitted into Purkinje fibers.

10.
Where are the blood vessels which supply the heart located?
a. Epicardium
b. Pericardium
c. Myocardium
d. Endocardium
e. Endomysium

Answer: a

The heart consists of three layers: epicardium, myocardium and endocardium.

The epicardium is the outer layer of the heart, containing the blood vessels and nerves which supply the heart.

The myocardium is the muscular layer of the heart.

The endocardium is the inner layer of the heart. The innermost portion of the endocardium is composed of endothelium, a simple squamous epithelium.

The pericardium is the connective tissue sac that the heart sits in.

Endomysium is the connective tissue covering of an individual muscle cell.