How are skeletal muscle and cardiac different?

Skeletal muscle and cardiac muscle, while both types of muscle tissue, exhibit several key differences:

1. Location: Skeletal muscles are attached to bones and enable voluntary movements, such as walking, running, and arm movement. They are predominantly found in limbs, trunk, and head. Cardiac muscle, on the other hand, is found exclusively in the heart and is responsible for pumping blood.

2. Structure: Skeletal muscle cells are long, cylindrical, and multinucleated, meaning they contain multiple nuclei. They have a striated appearance due to the arrangement of actin and myosin filaments, giving them a banded pattern. Cardiac muscle cells are also striated but are shorter and rectangular in shape. They typically have one or two nuclei and are branched, allowing for the formation of intercellular connections called intercalated disks.

3. Control: Skeletal muscles are under voluntary control, meaning we can consciously contract and relax them. Cardiac muscle, however, is involuntary, which means its contractions are not consciously controlled. The heart's rhythm is regulated by specialized cardiac cells known as pacemaker cells.

4. Contraction mechanism: Skeletal muscle contraction occurs through the sliding filament mechanism, where actin and myosin filaments slide past each other. ATP provides the energy for this process. Cardiac muscle contraction also involves the sliding filament mechanism, but it is triggered by the electrical impulses generated by the pacemaker cells.

5. Duration of contraction: Skeletal muscle contractions can be sustained for varying periods, depending on the activity. Cardiac muscle contractions, however, are rhythmic and involuntary. Each contraction lasts for a short duration, allowing for a continuous pumping action of the heart.

6. Fatigue: Skeletal muscles can fatigue or become exhausted after prolonged activity. This is because they rely on stored glycogen as their primary energy source, and once glycogen is depleted, muscle function declines. Cardiac muscle, on the other hand, is designed for continuous contraction and is relatively resistant to fatigue. It primarily utilizes fatty acids as its energy source.

These differences in structure, control, and function allow skeletal muscle and cardiac muscle to perform their specialized roles efficiently. Skeletal muscles provide voluntary movement and support, while cardiac muscle pumps blood throughout the body, ensuring the continuous circulation necessary for life.