Cardiac Muscles

Cardiac muscle (also known as heart muscle or myocardium) is one of three forms of muscle tissue found in vertebrates. The other two are skeletal and smooth muscle. It is an involuntary, striated muscle that makes up the majority of the heart’s wall tissue. Between the outside layer of the heart wall the pericardium and the inner layer the endocardium, the cardiac muscle myocardium creates a thick middle layer with blood supplied via the coronary circulation. Individual cardiac muscle cells are connected by intercalated discs, and the extracellular matrix is made up of collagen fibres and other components.

Cardiac Muscles

In vertebrates, cardiac muscle, commonly known as myocardium, is one of three major muscle groups found only in the heart. Cardiac muscle has a contractile unit known as sarcomeres, which makes it similar to skeletal muscle, another primary muscle type; however, this feature also distinguishes it from smooth muscle, the third muscle type. Cardiac muscle varies from skeletal muscle in that it contracts in a rhythmic pattern and is not controlled by the user. The sinoatrial node of the heart, which functions as the heart pacemaker, regulates the rhythmic contraction of cardiac muscle.

Cardiac muscle cells make up the majority of the heart (or myocardium). The contractility, which is the foundation for the heart pumping motion, and the rhythmicity of the contraction are two of the heart’s most notable properties. The cardiac output changes to fulfil the metabolic needs of peripheral tissues such skeletal muscles, kidneys, brain, skin, liver, heart, and gastrointestinal system. The contractile force created by cardiac muscle cells, as well as the frequency with which they are triggered, define cardiac output (rhythmicity). The frequency and force of cardiac muscle contractions are important parameters in determining the heart’s normal pumping performance and response to changes in demand.

Cardiac Muscle Structure

Cardiac muscle can only be found in animals’ hearts. It is a specific type of muscle that has evolved to contract continuously and repeatedly, allowing blood to circulate throughout the body. The heart is a straightforward organ. There are only three layers in all of the twists and turns and chambers. The epicardium or visceral pericardium is the outer layer that surrounds the heart muscle on the outside. This keeps it from colliding with other organs. The parietal pericardium connects to this outer layer, forming a fluid-filled layer that aids in lubrication of the heart. The endocardium, or inner layer, divides the muscle from the blood it pumps within the heart chamber. The heart muscle is located between these two sheets. Myocardium is a term used to describe cardiac muscle. The graphic below illustrates this.

When we look at heart muscle more closely, we can see that it is made up of sheets of cells that are joined in a lattice-work pattern. An intercalated disc is a specific connection that locks two cells together where they meet. Under the microscope, this region appears to be a dark disc, but it is actually the interlocking of hundreds of finger-like extensions from each cell. Gap junctions are microscopic pores in these projections that allow the impulse to contract to reach linked cells. Nerves and blood arteries run between and around these cells, carrying signals and oxygen to the heart muscle.

Function of Cardiac Muscle

The signal to contract is an action potential, just like in skeletal muscle. The somatic, or voluntary, neural system, on the other hand, normally sends this signal to skeletal muscle. The autonomic nerve system is in charge of controlling cardiac muscle. Well-timed nerve impulses are released by cells in your brain and cells embedded throughout your heart, signalling your heart cells to contract in the proper rhythm. While the signals’ sources differ, the signal’s receipt and the remainder of the contraction are fairly similar.

The action potential, also known as a nerve impulse, triggers a specific organelle on the cell’s surface to release calcium ions Ca2+. The sarcoplasmic reticulum is a type of organelle that is derived from the endoplasmic reticulum of a typical cell. Troponin is affected by Ca2+ ions released into the cytoplasm, prompting it to release tropomyosin. Tropomyosin moves out of the way, allowing myosin to connect to actin. The energy stored in ATP molecules was then used by myosin to move along the actin filaments and shrink the length of each sarcomere. Ca2+is readily reabsorbed into the sarcoplasmic reticulum after the impulse has passed. Troponin binds to tropomyosin again, causing cardiac muscle cells to release. Every time your heart beats, this general procedure occurs.

In the chambers of the heart, a force may be exerted because all of the muscle cells function in harmony. The sheets of heart muscle are arranged in a perpendicular pattern. When the heart contracts, it does so in a different direction as a result of this. As these many layers of fibres contract, the heart’s ventricles and atria diminish from top to bottom and side to side. This causes the ventricles to pump and twist vigorously, propelling blood throughout the body.

Conclusion

Cardiac muscle is one of three types of muscle tissue present in vertebrates. It is also known as heart muscle or myocardium. Skeletal and smooth muscle are the other two. It is a striated muscle that makes up the majority of the heart’s wall tissue and is involuntary. 

Cardiac muscle, also known as myocardium, is one of three major muscle groups found only in the heart in vertebrates. Cardiac muscle has sarcomeres, which make it comparable to skeletal muscle, another basic muscle type; however, this trait distinguishes it from smooth muscle, the third muscle type. Cardiac muscle is distinguished from skeletal muscle by the fact that it contracts in a rhythmic pattern and is not controlled by the user.