Differences between Cardiac and Skeletal Muscles

The structured myofibrils and numerous aligned Sacro-meres in cardiac and skeletal muscles give them striated appearances. Aside from the similarities already mentioned, cardiac and skeletal muscles differ in a few ways. The fact that cardiac muscles are shorter and have a smaller diameter and length than skeletal muscles is one of the contrasts between them. The diameter and length of cardiac muscles are 9–12 um and 50–100 cm, whereas those of skeletal muscles are 100 um and up to 30 cm, respectively. Another difference is that a cardiac muscle nucleus is usually single and others may have two or more nuclei and centrally placed while the nuclei of a skeletal muscle are multiple and located near sarcolemma.

The two muscles have a difference in the energy source. The energy source for the skeletal muscle is the “aerobic metabolism at moderate level of activity: glycolysis (anaerobic) during peak activity” (Johnson and Byrne, 236) while for the cardiac muscles is the aerobic metabolism of either carbohydrate or lipid substrates. Another difference of skeletal and cardiac muscles is on contraction. The contraction of the skeletal muscles starts rapidly and can be tetanized and this results in a rapid fatigue. The contraction of cardiac muscles on the other end is slower at the start and cannot be tetanized and this makes it resistant to fatigue. Both the muscles also differ in their movement. The cardiac muscles are controlled involuntarily while the skeletal muscle movement is controlled by the somatic nervous system. The shape of the two types of muscle also makes them differ. The skeletal muscles are cylindrical in shape a factor which makes them run a muscle length and this is why they are long while the cardiac muscles are cylindrical and branched.

Work Cited

Johnson, Leonard R., and John H. Byrne. "Muscle Tissue." Anatomy and Physiology, 2007 ed., Pearson Education South Asia Pte. Ltd, 2007, p. 236.