Difference Between Smooth Muscles and Cardiac Muscles

Smooth Muscles vs Cardiac Muscles

The two most confusing muscle types are the cardiac muscle and smooth muscle. The reason for such confusionmay be because of both being characterized with involuntary contractions unlike the long and powerful skeletal muscles (somatic muscles) that can contract voluntarily. Nevertheless, cardiac and smooth muscles still differ in other aspects.

Cardiac muscles are striated (have striations or lines) which is almost similar to that of skeletal muscles. The cardiac muscles also have many nuclei that act as one single unit. This type of muscle is unique in the sense that its fibers link and split into chains through intercalated disks. It is because of the latter that communication between the cells is made possible thus resulting in the presence of seemingly timed myocardial contractions. This actually lessens the burden on the brain because it no longer has to transmit signals to each cardiac muscle just to let your heart contract.

The cardiac muscle is the tissue the makes up your myocardium and the external cardiac walls. It also represents the other major blood vessels of the circulatory system such as the aorta. The smooth muscles are different because they cover most of the other blood vessels of your body. In general, the smooth (also known as visceral) muscles line your blood vessels and other internal organs. All the ducts or tubes, cavities and linings of your urinary, digestive, genital, and respiratory systems are all made up of smooth muscles. According to some expert anatomists, smooth muscles also make up the eyeball and some layers of the skin.

Smooth muscles are named as such because of the absence of striations. They are also sturdier than cardiac muscles in the sense that they can stretch at greater lengths and can sustain longer contractions as compared to cardiac muscles. They can do such without the occurrence of injury. But this does not mean that your heart cannot be overworked. As a matter of fact, many hearts become stressed out easily because the heart needs a huge amount of blood for it to function effectively. If they are overworked, they tend to increase in size while if the smooth muscles become overworked, they tend to increase in number and in size. In addition, once the heart is injured, it cannot be regenerated unlike smooth muscles.

The two also differ in the nature of their control. The heart, for example, has its own cardiac muscle pacemaker that regulates its beating which is under the control of the autonomic nervous system (the nervous system division of the unconscious or automatic nerve response). For smooth muscles, there’s direct innervations wherein the autonomic system directly influences the activities of the smooth muscles present in the internal organs. Additionally, hormones can also trigger some activities of the smooth muscles.

Summary of  Smooth Muscles vs Cardiac Muscles

1.Cardiac muscles are striated unlike smooth muscles.
2.Cardiac muscles are found in the heart walls and aorta while smooth muscles are found in the majority of blood vessels and internal organs.
3.The cardiac muscle is innervated by the autonomic nervous system via its cardiac pacemaker while smooth muscles are directly innervated by this system.
4.Cardiac muscles do not regenerate when injured unlike the smooth muscles.

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