Which tissue type exhibits autorhythmicity?

Which tissue type exhibits autorhythmicity?

• A. Nodal cells
• B. Contractile cardiac myocytes
• C. Endothelial cells
• D. Fibroblasts of the myocardium

Answer: (A)

Autorhythmicity is the ability of certain heart cells to generate their own rhythmic action potentials without neural input. Nodal cells, especially in the sinoatrial node, have a pacemaker potential that slowly depolarizes due to the funny If current, reaching threshold and triggering action potentials at regular intervals. This intrinsic automaticity sets the heart’s rhythm. Contractile cardiac myocytes have stable resting potentials and rely on impulses from nodal tissue to contract; endothelial cells line vessels and fibroblasts are structural supports, neither of which generate automatic impulses. So the nodal tissue is the one that exhibits autorhythmicity.

Autorhythmicity is the ability of certain heart cells to generate their own rhythmic action potentials without neural input. Nodal cells, especially in the sinoatrial node, have a pacemaker potential that slowly depolarizes due to the funny If current, reaching threshold and triggering action potentials at regular intervals. This intrinsic automaticity sets the heart’s rhythm. Contractile cardiac myocytes have stable resting potentials and rely on impulses from nodal tissue to contract; endothelial cells line vessels and fibroblasts are structural supports, neither of which generate automatic impulses. So the nodal tissue is the one that exhibits autorhythmicity.