Cardiac Conduction Flashcards
The only electrical connection point between the atria and ventricles
Atrioventricular (AV) node
The first cells to initiate an electrical signal in the heart
Sinotrial (SA) node
Electrically connects the left and right atria
Bachmann’s Bundle
Found immediately after the signal enters the ventricles
Bundle of His (AV bundle)
Final part of the conduction system
Purjunke Fibers
Provides cytoplasmic connections between cells of the heart
Gap Junction
Cells that are functionally working as one unit
Sytnctium
The ability to spontaneously complete something
Automaticity
T or F: The atria and ventricles contract at the same time in a normal, functioning heart.
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).
T or F: The electrical current (signal) moves slower through the the conductive cells compared to its movement through regular cardiomyocytes (heart muscle cells).
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.
T or F: Cardiac muscle cells can be branched.
True
T or F: Gap junctions prevent ions from being transported between cardiac muscle cells.
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.
T or F: Desmosomes help to physically attach cardiac muscle cells to each other.
True: Desmosomes are protein structures that act like “staples” to form physical connections (at intercalated discs) between neighboring cardiac muscle cells
Which structures are part of intercalated discs?
Gap Junctions and Desmosomes
What is the main function of the atrioventricular (tricuspid and bicuspid/mitral) valves?
To prevent the flow of blood from ventricles to atria during ventricular ejection
During atrial systole, which of the following pressure gradients exist?
Higher pressure in atria compared to ventricles
In the heart, blood will flow from areas of low pressure to areas of high pressure (assuming no valves are present).
False
Which stage of the cardiac cycle helps to fill ventricles to maximum blood volume?
Atrial Systole
During the quiescent period, blood is filling both the atria and the ventricles.
True
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
I and II
A toxin destroys gap junctions of cardiac tissue. Which result might you expect?
Propagation of action potentials between cells will be disrupted.
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)?
Ventricles contract from the bottom of the ventricles toward the base of the heart.
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?
No impulses would get through, and the ventricles would beat at their intrinsic rate, which is much slower.
What is the T wave
What structure will blood flow directly into after leaving the pulmonary veins?
No atrial depolarization
