What is excitability in the context of cardiac cells?

What is excitability in the context of cardiac cells?

• A. The ability to initiate impulses without external stimuli
• B. The ability to respond to a stimulus
• C. The ability to return to resting state after contraction
• D. The ability to conduct impulses across cell membranes

Answer: (B)

In the context of cardiac cells, excitability refers to the ability of these cells to respond to a stimulus. When cardiac cells, specifically the myocardial cells, receive an adequate stimulus, they undergo a change in their membrane potential, leading to depolarization and the generation of an action potential. This ability to respond is essential for the proper functioning of the heart, as it enables the rhythmic contractions needed for effective blood circulation. The other choices describe different properties related to cardiac function. The ability to initiate impulses without external stimuli pertains to automaticity, a characteristic of certain cardiac cells like pacemaker cells. The ability to return to the resting state after contraction relates to the process of repolarization. Conducting impulses across cell membranes refers to the property of conductivity, which allows the action potential to propagate through cardiac tissue. While all these properties are vital for cardiac physiology, excitability specifically focuses on the responsiveness of cardiac cells to stimuli.

In the context of cardiac cells, excitability refers to the ability of these cells to respond to a stimulus. When cardiac cells, specifically the myocardial cells, receive an adequate stimulus, they undergo a change in their membrane potential, leading to depolarization and the generation of an action potential. This ability to respond is essential for the proper functioning of the heart, as it enables the rhythmic contractions needed for effective blood circulation.

The other choices describe different properties related to cardiac function. The ability to initiate impulses without external stimuli pertains to automaticity, a characteristic of certain cardiac cells like pacemaker cells. The ability to return to the resting state after contraction relates to the process of repolarization. Conducting impulses across cell membranes refers to the property of conductivity, which allows the action potential to propagate through cardiac tissue. While all these properties are vital for cardiac physiology, excitability specifically focuses on the responsiveness of cardiac cells to stimuli.