Major Functions of Cardiac & Smooth Muscles

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  • 0:01 Types of Muscles
  • 0:45 Cardiac Muscle
  • 2:38 Smooth Muscle
  • 4:09 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Did you know that you can't control all of your muscles? Some muscles, such as cardiac and smooth muscles work, without you thinking about them. Learn about these involuntary muscles and how they help with things like pumping blood and digesting food.

Types of Muscles

When you think about muscles, you probably think about the muscles in your arms and legs that allow you to lift heavy objects and run really fast. Those muscles are called voluntary muscles because you choose to move them, but not all of the muscles in your body work that way. The muscles of your heart, organs and other internal structures are involuntary muscles because they are hard at work regardless of what you are doing; they even work while you sleep.

There are two types of involuntary muscles inside of you: cardiac muscle and smooth muscle. In this lesson, we will learn more about these types of muscles and how you depend on them to stay alive.

Cardiac Muscle

Did you ever watch a medical show on television where one of the patients went into cardiac arrest? If so, you probably know that means they were having a heart attack. Because the word 'cardiac' refers to things dealing with the heart, it is easy to see that cardiac muscle is the type of muscle that makes up your heart. This muscle is also known as the myocardium, which sounds like a big scientific word but is fairly easy to understand if you break it down. The prefix 'myo' refers to muscle, and the word 'cardium' is really close to cardiac, or heart, so the term 'myocardium' is literally the muscle of the heart.

The cardiac muscle has only one job, but it is a very important one; its job is to pump blood through the miles of blood vessels in your body. If the cardiac muscle stops, you stop. It's a good thing you don't have to consciously think about contracting your heart muscle. If you did, you would never be able to sleep!

Not only is cardiac muscle involuntary; I guess you could say it marches to its own beat. That's because your heart has its own electrical system that causes it to beat consistently, and the crazy thing about that is a heart will continue to beat even after it's removed from the body. All it needs is oxygen. If it has that, it will continue to beat!

One other thing to note about cardiac muscle is its appearance. If you were to put a slide containing a sliver of heart muscle under a microscope, you would notice that cardiac muscle is striated, which simply means it looks like it is striped. This fact is one of the differences between cardiac muscle and smooth muscle.

Smooth Muscle

Smooth muscle is the type of muscle that makes up the walls of many internal organs and structures. You will find this type of muscle in your digestive tract, blood vessels and bladder. Unlike cardiac muscle, it is not striated; instead it looks like smooth sheets of muscle.

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