Cardiac Conduction

Question 1

The only electrical connection point between the atria and ventricles

Answer 1

Atrioventricular (AV) node

Question 1

The first cells to initiate an electrical signal in the heart

Answer 1

Sinotrial (SA) node

Question 2

Electrically connects the left and right atria

Answer 2

Bachmann’s Bundle

Question 3

Found immediately after the signal enters the ventricles

Answer 3

Bundle of His (AV bundle)

Question 4

Final part of the conduction system

Answer 4

Purjunke Fibers

Question 5

Provides cytoplasmic connections between cells of the heart

Answer 5

Gap Junction

Question 6

Cells that are functionally working as one unit

Answer 6

Sytnctium

Question 7

The ability to spontaneously complete something

Answer 7

Automaticity

Question 8

T or F: The atria and ventricles contract at the same time in a normal, functioning heart.

Answer 8

False; Because of the delay at the AV node, the atria contract milliseconds before the ventricles. This helps to promote proper blood flow from atria –> ventricles –> arteries (out to the body).

Question 9

T or F: The electrical current (signal) moves slower through the the conductive cells compared to its movement through regular cardiomyocytes (heart muscle cells).

Answer 9

False; The depolarization to threshold occurs faster in conductive cells compared to the surrounding cardiomyoctes. This allows the conductive cells to direct the signal in an organized manner so that the contraction of the heart promotes proper blood flow.

Question 10

T or F: Cardiac muscle cells can be branched.

Answer 10

True

Question 11

T or F: Gap junctions prevent ions from being transported between cardiac muscle cells.

Answer 11

These protein structures allow a direct, cytoplasmic connection between neighboring cells (at intercalated discs) so that ions can easily diffuse from one cell to the next.

Question 12

T or F: Desmosomes help to physically attach cardiac muscle cells to each other.

Answer 12

True: Desmosomes are protein structures that act like “staples” to form physical connections (at intercalated discs) between neighboring cardiac muscle cells

Question 13

Which structures are part of intercalated discs?

Answer 13

Gap Junctions and Desmosomes

Question 14

What is the main function of the atrioventricular (tricuspid and bicuspid/mitral) valves?

Answer 14

To prevent the flow of blood from ventricles to atria during ventricular ejection

Question 15

During atrial systole, which of the following pressure gradients exist?

Answer 15

Higher pressure in atria compared to ventricles

Question 16

In the heart, blood will flow from areas of low pressure to areas of high pressure (assuming no valves are present).

Answer 16

False

Question 17

Which stage of the cardiac cycle helps to fill ventricles to maximum blood volume?

Answer 17

Atrial Systole

Question 18

During the quiescent period, blood is filling both the atria and the ventricles.

Answer 18

True

Question 19

Which of the following characteristics is/are shared by both skeletal and cardiac muscle?

I. Sarcomere organization
II. Branched cells
III. Excitability
IV. Single nucleus per cell

Answer 19

I and II

Question 20

A toxin destroys gap junctions of cardiac tissue. Which result might you expect?

Answer 20

Propagation of action potentials between cells will be disrupted.

Question 21

Thinking about the structure of the heart, which of the following statements best describes ventricular contraction for proper blood flow (remember that blood leaves the heart via the great vessels)?

Answer 21

Ventricles contract from the bottom of the ventricles toward the base of the heart.

Question 22

Heart block refers to a condition in which either the AV node, AV bundle, or one or both bundle branches are damaged. What would you expect to see with complete heart block?

Answer 22

No impulses would get through, and the ventricles would beat at their intrinsic rate, which is much slower.

Question 23

What is the T wave

Question 24

What structure will blood flow directly into after leaving the pulmonary veins?

Answer 24

No atrial depolarization