Myocardial contraction

Definition

Myocardial contraction is the process by which the heart muscle (myocardium) contracts to pump blood throughout the body. This contraction is initiated by electrical impulses that propagate through the cardiac conduction system.

5 Must Know Facts For Your Next Test

1. The primary driver of myocardial contraction is the sinoatrial (SA) node, also known as the heart's natural pacemaker.
2. Calcium ions play a crucial role in triggering myocardial contraction by facilitating actin-myosin cross-bridge formation within cardiac muscle cells.
3. Myocardial contraction strength can be influenced by pharmacological agents such as inotropes, which either increase or decrease contractility.
4. The refractory period following a myocardial contraction prevents immediate re-excitation, ensuring coordinated pumping action of the heart chambers.
5. Abnormalities in myocardial contraction can lead to arrhythmias, heart failure, or other cardiovascular diseases.

Review Questions

• What role do calcium ions play in myocardial contraction?
• How does the sinoatrial (SA) node influence myocardial contraction?
• Name one pharmacological agent that affects the strength of myocardial contraction and explain its effect.

Related terms

Sinoatrial Node: A group of specialized cells located in the right atrium that act as the natural pacemaker of the heart.

Inotrope: A substance that alters the force or energy of cardiac muscular contractions.

Refractory Period: The time during which a cell is incapable of repeating an action potential, crucial for proper timing of cardiac contractions.