Question 1

Cardiac muscle cells obtain energy almost exclusively through ________.

Accepted Answer

Cardiac muscle cells have a high demand for energy due to their constant contractions. Aerobic respiration provides a large amount of energy in the form of ATP, which is necessary for these contractions to occur. Anaerobic pathways can only provide a limited amount of energy and often lead to the production of lactic acid, which can be harmful to the cells. Glycolysis and the Krebs cycle are also part of aerobic respiration and can contribute to energy production, but they are not exclusively used by cardiac muscle cells. Protein reserves can be used for energy, but they are not the primary source for cardiac muscle cells.

Question 2

Blood that is moved to and from all of the tissues of the body (with the exception of the lungs)is transported in the ________.

Accepted Answer

The systemic circuit involves the movement of blood from the heart to all of the tissues of the body (excluding the lungs) and then back to the heart, making it the correct answer. The pulmonary circuit only involves the movement of blood to and from the lungs. The hepatic portal circuit involves the movement of blood from the digestive organs to the liver. The arterial circle of Willis is part of the circulatory system in the brain. The infundibular circuit is not a recognized term in the human circulatory system.

Question 3

Which describes the endocardium?
a.Has single layer of epitheliumt
b. Has layer of areolar connective tissue
c.Epithelial cells are squamous
d. Epithelial cells are cuboidal
e. Has layer of smooth muscle tissue

Accepted Answer

The endocardium is the innermost layer of the heart, consisting of a single layer of squamous epithelial cells (endothelium) overlying a thin layer of areolar connective tissue. It does not have cuboidal epithelial cells or a layer of smooth muscle tissue.

Question 4

The visceral pericardium is also called the ________.

Accepted Answer

The visceral pericardium is the outermost layer of the heart, which forms the inner lining of the pericardial sac. It is also known as the epicardium.

Question 5

The extensive connective tissue network, which encircles the bases of the pulmonary trunk and aorta and the valves of the heart, is called the ________ of the heart.

Accepted Answer

The cardiac skeleton is the extensive connective tissue network that encircles the bases of the pulmonary trunk and aorta and the valves of the heart. It provides structural support for the heart and serves as an attachment site for the cardiac muscle fibers.

Question 6

The ________ carries blood to and from the gas exchange surfaces of the lungs.

Accepted Answer

The pulmonary circuit includes the pulmonary arteries which carry deoxygenated blood from the heart to the lungs for gas exchange and the pulmonary veins which carry oxygenated blood from the lungs back to the heart.

Question 7

The primary function of the pericardial fluid is to provide ________ between the pericardial membranes.

Accepted Answer

The main function of pericardial fluid is to provide lubrication between the pericardial membranes, allowing for smooth movement of the heart during contractions and relaxation.

Question 8

Which of the following is a function of the cardiac skeleton of the heart?

Accepted Answer

The cardiac skeleton separates and isolates atrial and ventricular muscle cells, allowing them to contract independently and efficiently. It also provides support for the valves and electrical conduction system of the heart. It does not provide instructions for cardiac muscle cells to contract, maintain energy reserves, or physically connect the atrial and ventricular muscle cells.

Question 9

Which heart structure receives blood from the systemic circuit?

Accepted Answer

The right atrium receives deoxygenated blood from the systemic circuit via the superior and inferior vena cavae.

Question 10

The pericardial cavity is actually ________.

Accepted Answer

The pericardial cavity is considered a potential space because it normally contains a small amount of lubricating fluid, allowing the heart to move smoothly within the pericardium. It is not a large space, does not contain mucin, typically contains less than 50 mL of pericardial fluid, and actually reduces friction between the heart and pericardium.

Question 11

The exchange of oxygen and carbon dioxide in the cardiovascular system occurs in which vessels?

Accepted Answer

Capillaries are the smallest and narrowest vessels in the cardiovascular system, where exchange of gases (oxygen and carbon dioxide) takes place between the bloodstream and the surrounding tissues. Oxygen from the capillaries diffuses into the cells, while carbon dioxide generated by cellular respiration moves into the bloodstream to be transported to the lungs for elimination. Thus, capillaries are known as the sites of gas exchange in the cardiovascular system.

Question 12

Which of these statements can be used to characterize blood flow in the human body?
a.There is a unidirectional blood flow.
b. Arteries always carry oxygenated blood.
c. Veins always carry deoxygenated blood.
d. Arteries always carry blood away from the heart.
e. Veins always carry blood toward the heart.

Accepted Answer

Statement a is correct as blood flow in the human body is unidirectional due to the presence of one-way valves in veins. Statement b is incorrect as arteries may sometimes carry deoxygenated blood (e.g. pulmonary artery). Statement c is incorrect as veins may sometimes carry oxygenated blood (e.g. pulmonary vein). Statement d is correct as arteries always carry blood away from the heart, while statement e is incorrect as some veins (e.g. renal veins) carry blood away from the heart. Therefore, only choice C is correct.

Question 13

The intercalated disc of cardiac muscle cells possess a specialized form of communicating junction termed a(n)________.

Accepted Answer

The specialized form of communicating junction found in the intercalated discs of cardiac muscle cells is the gap junction. Gap junctions allow for direct passage of ions and small molecules between cells, allowing for coordinated electrical and metabolic activity in the heart. Desmosomes (A) and macula adherens (B) are types of anchoring junctions that provide mechanical stability to tissues. Fascia adherens (D) is a specialized form of adherens junction found in cardiac muscle cells. CAMs (E) are cell adhesion molecules involved in cell-cell interactions, but they do not form specialized junctions like those found in the intercalated discs.

Question 14

Which element of the fibrous pericardium stabilizes the position of the heart and associated vessels within the mediastinum?

Accepted Answer

Collagen fibers are the main structural component of the fibrous pericardium that provide strength, durability, and stability to the heart and associated vessels within the mediastinum.

Question 15

Cardiac muscle cells differ from skeletal muscle fibers in that the cardiac muscle cells are uniquely interconnected by (the)________.

Accepted Answer

Cardiac muscle cells are uniquely interconnected by intercalated discs, which are specialized cell-to-cell connections that allow for rapid and coordinated contraction of the heart. Unlike skeletal muscle fibers, which rely on neuromuscular junctions to communicate with each other and stimulate contraction, cardiac muscle cells can communicate directly through gap junctions in the intercalated discs.

Question 16

The cardiac skeleton of the heart functions to ________.

Accepted Answer

The cardiac skeleton serves several functions, including providing elasticity to aid in the return of the heart to its original shape, physically separating the atrial and ventricular muscle cells, distributing the force of contraction throughout the heart, and reinforcing the heart valves. Therefore, all of the answer choices are correct.

Question 17

Because cardiac muscles are mechanically, chemically, and electrically connected to one another, cardiac muscle tissue functions like a single enormous muscle cell. For this reason, it is called a functional ________.

Accepted Answer

The term "syncytium" refers to a single, multinucleated cell formed by the fusion of smaller cells. In the case of cardiac muscle tissue, the mechanical, chemical, and electrical connections between individual cardiac muscle cells create a syncytium, which functions as a single, coordinated unit.

Question 18

The outermost layer of the serous pericardium is termed the ________.

Accepted Answer

The outermost layer of the serous pericardium is called the parietal pericardium. The fibrous pericardium is an outer layer of tough connective tissue that surrounds and stabilizes the heart, while the visceral pericardium (also known as the epicardium) is the inner layer of the serous pericardium that directly covers the heart surface. The endocardium is the innermost layer of the heart wall, lining the chambers and valves.

Question 19

Which structures are responsible for creating a direct electrical connection between cardiac muscle cells?

Accepted Answer

Gap junctions are specialized protein channels that allow ions and small molecules to pass directly between cardiac muscle cells, providing a direct electrical connection that allows for coordinated contraction of the entire heart. Maculae adherens, desmosomes, intercalated discs, and fascia adherens are all important structures that help anchor cardiac muscle cells together, but do not directly facilitate electrical communication.

Question 20

Which is the layer that lines the internal surface of the heart wall?

Accepted Answer

The endocardium is the layer that lines the internal surface of the heart wall. It is composed of a layer of endothelial cells and provides a smooth surface for blood to flow through the heart.

Quiz 21: The Cardiovascular System: The Heart