Excite Your Knowledge of Cardiomyocyte Function with this Quiz!

Understanding the Mechanisms of Excitation Contraction Coupling in Cardiomyocytes

• The talk focuses on understanding the molecular and physiological mechanisms of how the electrical excitability of each action potential drives the ventricular contraction that injects blood into the aorta and the vascular tree.
• Information gathered from single ventricular cardiomyocytes will be considered to understand how an action potential increases cytosolic calcium and how that elevation affects the contraction of the cell.
• Different parts of the mechanisms of excitation contraction coupling may be targeted in different cardiac disease circumstances that may result in the dysfunction of the heart tissue.
• Ventricular cardiomyocytes have a resting membrane potential of between -80 and -90 millivolts, which is very negative relative to the outside environment.
• When the plasma membrane is excited by an electrical stimulation, there's a very fast and large increase in the delivery of positive charge to the cell by the entry of sodium ions through their sodium channels.
• The L-type calcium channels open and let calcium ions pass through them from the outside to the inside when the membrane potential moves to the region of -40 millivolts, resulting in a peak and a plateau traditional of the ventricular cardiomyocyte action potential waveform.
• The electrical action potential elevates intracellular calcium to produce contraction.
• The structure of cardiomyocytes is important to consider because structure determines function, and cardiomyocytes have a distinctive structure where the intracellular appearance of the cells is of a striated nature of alternating relatively light and dark banding patterns.
• Sarcomeric structures, which are depicted by the boundaries of thick lines that are transverse to the plasma membrane, delineate the protein components of the cell into the so-called sarcomeric structures.
• The light and dark banding pattern reflects the relative distributions of thick and thin filaments, where thick myosin-containing filaments and thin actin-containing filaments interact to control the contractile nature of the sarcomeric unit.
• The Zed lines or Zed disks give rigidity to those sarcomeric structures, and the M line provides extra stability to that unit.
• Understanding the mechanisms of excitation contraction coupling in cardiomyocytes is crucial for understanding how the heart functions and how disruptions in these mechanisms may lead to different cardiac disease circumstances.