What Is Cardiac Muscle Tissue?

Only the walls of the heart have cardiac muscle tissue.
Cardiac muscle tissue contains characteristics associated with both smooth and skeletal muscle tissue.
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  • Written By: Mary McMahon
  • Edited By: Kristen Osborne
  • Last Modified Date: 12 September 2014
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Cardiac muscle tissue is a highly specialized type of muscle found only in the walls of the heart. This muscle type has a number of unique properties that allow it to regularly contract in order to force the heart to beat. On a microscopic level, it has some distinct features that make it easy to identify and allow an examiner to differentiate it from other types of muscles.

The body also includes voluntary or skeletal muscle that connects to the skeleton to allow it to articulate and move, along with involuntary or smooth muscle like that found in the bowels. Both types of muscle respond to signals from the nerves. People can voluntarily initiate movements of the skeletal muscle, but the smooth muscle is not under conscious control.

Cardiac muscle tissue contains a blend of characteristics associated with both tissues. Like skeletal muscles, it has a striated appearance and the cells can have more than one nucleus. As with smooth muscle tissue, the cardiac muscle tissue is not under voluntary control. Unlike both other types of muscles, input from the nerves is not needed to stimulate muscle contractions. The contractions of the cardiac muscles are mediated by specialized pacemaker cells.

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When viewed under a microscope, this tissue's highly branched appearance becomes visible. In addition, markings known as intercalated discs can be seen where individual muscle cells join together. These discs facilitate rapid communication, allowing the heart to coordinate muscular contractions. This type of muscle tissue is also designed for very high endurance and should not tire like other muscles.

The heart muscle is famous for being extremely tough, a consequence of the demands placed on this tissue type. The intertwined network of chains of muscle cells makes the heart resilient and very sturdy. While the heartbeat in the chest may feel relatively faint unless someone is under stress or working out, the heart is actually a very active organ, as can be seen in videos of surgeries involving the heart.

Historically, it was believed that cardiac muscle tissue was not capable of renewing itself like many other types of tissue are. Research has since demonstrated that it actually does, but at a very slow rate. Starting at around age 20, approximately one percent of the cardiac muscle tissue is replaced every year. Understanding the inner workings of this type of muscle tissue is important for people interested in cardiac conditions such as cardiomyopathy.

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wavy58
Post 5

In the college biology class I’m currently taking, we are studying the makeup of the human heart. I just learned that the most cardiac muscle tissue is found in the myocardium.

The myocardium is the heart’s thick middle layer. It is made almost entirely of cardiac muscle tissue and blood vessels, and the inside of it is covered with the endocardium.

This thick heart layer makes up the majority of the wall of the heart. It contracts when the heart beats.

orangey03
Post 4

I think that my dog died of cardiomyopathy. The vet said it was either that or poisoning, and since she hadn't been exposed to anything toxic, I think it was the cardiac condition.

She had no symptoms until the day she died. She started vomiting and collapsed. She went into a coma, and we rushed her to the vet. She had fluid around her lungs, and her heart rate was rapid.

These are all signs of cardiomyopathy in dogs. It affects large breeds around the age of 5, and that's how old she was. The disease is hereditary, but I didn't know her parents, so there's no way I could have gotten treatment for her in time.

JaneAir
Post 3

@Azuza - They sure do like to throw around those medical words on TV! It's funny how really impressive sounding words mean something so simple.

I must admit I have a soft spot in my heart for cardiac muscle tissue. When I was struggling through Anatomy and Physiology in college I always found it to be the easiest tissue to identify. The intercalated discs gave it away every time!

seag47
Post 2

I have cardiomyopathy, and I didn’t know it until the disease had advanced. The early stages generally don’t produce symptoms.

I started to become breathless when doing the least little activities. Sometimes I felt out of breath even while just sitting there. My ankles started to swell, I was tired all the time, I felt dizzy a lot, and I had rapid irregular heartbeats that sometimes came in the form of pounding.

I am currently taking a diuretic and ACE inhibitors to manage the condition. The medication has helped reduce the unpleasant symptoms.

Azuza
Post 1

I feel like I hear the word cardiomyopathy on medical shows on TV all the time. After seeing it in this article my curiosity was piqued so I looked it up and now I see why it was mentioned: cardiomyopathy is a disease of the heart muscle!

There are a few different kinds of cardiomyopathies with several different causes. It can be caused by decreased blood flow to the heart, chemotherapy, and alcoholism. Very interesting.

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