|THE MUSCULAR SYSTEM|
Skeletal, Smooth and Cardiac Muscles
Move it or Lose it! This term can be directly applied to a sarcomere. A sarcomere is tiny portion of a myofibril (myo means muscle), which is a portion of a single muscle fiber, which is part of a bundle of muscle fibers we call 'the muscle'. If you don't move and exercise those muscles by contracting and relaxing them, you will in fact lose 100 sarcomere's a day per myofibril. YIKES! One single muscle fiber from a biceps muscle may contain 100,000 sarcomeres. So losing 100 sarcomere's a day from one muscle fiber will add up quickly if you have sedentary lifestyle. It won't take long to waste away, in fact, it will take right at about 3 months.
There are more than 639 skeletal muscles in your body. Some sources will say 640 muscles in the human body. On average, your body weight is 40% muscle. Out of the 639/640 muscles, 30 of them are facial muscles, which help you create all those different faces of happiness, surprise, joy, sorrow, sadness, fright, etc.
The muscles surrounding your eye are the busiest muscles in your body. Research indicates that you probably blink them more than 100,000 times a day. The biggest muscle in your body is the gluteus maximus (your butt).
Each muscle belongs to one of three categories: skeletal muscles, which move bones - smooth muscles, which control involuntary movements such as breathing and digestion, - and cardiac muscle, which is found in the heart.
The job of a muscle is to move your body. Without muscles you couldn't move your skeleton. There would be no way to animate your physical body or even speak your mind. You wouldn't be able to blink, digest your food, breathe, pump your heart or have one for that matter since your heart is a muscle. You couldn't smile, urinate, defecate or sniff with your nose.
Muscles are a type of tissue that is composed of contractile cells or fibers. The cells or fibers actually contract! And when they contract, they create movement on the bone that they attached to. The really cool thing about muscles tissue is its ability to shorten (contract). Muscle tissue also has the property of irritability, conductivity and elasticity.
Remember, there are three different types of muscle tissue:
- Smooth muscle: This muscle tissue is called involuntary because it is NOT under conscious control. Involuntary means you do not have to think about it. Involuntary muscle tissue is found in the internal organs; namely the digestive tract, respiratory passages, urinary and genital ducts, urinary bladder, gallbladder, walls of the blood vessels. Yep! Your blood vessel walls are also muscle tissue. Another great reason to exercise and pump the blood.
- Striated muscle: This muscle tissue is found in all skeletal muscles, and movement is under conscious control. It also occurs in the tongue, pharynx, and upper portion of the esoophagus. Voluntary muscles are under conscious control because you would consciously tell them what to do. If you say, "arm, move" it moves!
- Cardiac muscle: This muscle tissue is only found in the heart. The fibers branch and form a continuous network. At certain intervals, there are prominent bands or intercalated disks that cross the fibers. Some fibers are called Purkinje fibers, and they form the impulse-conducting system of the heart.
Muscles work by contracting and relaxing. Pump your bicep for a second. Make a fist and bring it up to your ear. Notice how your bicep gets bigger when the muscle tightens and shortens. And when you relax your arm, the muscle gets longer and smaller. Muscles do not push, they pull. The tiny muscle fibers work like a sliding glass door on a track. And these tiny muscle fibers get their energy from the food you eat. Without food to feed the muscles, your muscles couldn't make the energy to contract. The reason you can move your arm back and forth is because muscles work in pairs. One is a synergist, the other a antagonist. It's a support thing and so they can pull in opposing directions.
In order for a muscle to work, it has to cross a joint. Connecting from one end of a bone to the other without crossing the joint would be pretty much useless because it wouldn't be able to shorten or lengthen with the movement of the joint. So in order to bend your knee, the muscles in your thigh have to cross over to the other side of the knee joint and attach. Then when you tighten the muscle, the knee bends. Cool huh?
The muscles that are voluntary get their signals from the peripheral nervous system, and it's because of this that the skeletal muscles are under conscious or voluntary control. The involuntary muscles (smooth and cardiac muscles) receive their nerve supply from the central nervous system and functions involuntarily without conscious control.
It is possible to hurt a muscle because they can become pulled, hence "pulled muscle." You can actually tear a muscle the same way that a ligament or tendon gets torn or a bone gets broke. And the cool thing is, they can heal themselves with rest and time.
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**This web site's goal is to provide you with information that may be useful in attaining optimal health. Nothing in it is meant as a prescription or as medical advice. You should check with your physician before implementing any changes in your exercise or lifestyle habits, especially if you have physical problems or are taking medications of any kind.