why do we need muscles in the human body

Did you know that there are over 600 muscles in the human body? Why DO we need muscles anyway? What do they do for us? Why do we have muscles? Why do we need 3 different kinds of muscles? Muscles are responsible for the movement of almost everything in the body and they are very important. We would not be able to function without them. Muscles convert the body's chemical energy into a physical contraction. They provide the basic ability to move the bones and other systems of the body, which allows the body to function. They pull on our bones in order for them to move. Muscles are not only responsible for movement but they are also responsible for our posture, joint stability and heat production. Our posture and movement is a result of muscle contraction. As far as heat production goes, muscles produce nearly 85 percent of our body heat. There are three different types of muscles in the human body. These muscles include the skeletal muscles, cardiac muscles and smooth muscles. Skeletal muscles are primarily attached to the bones. They appear to be striated, multi-nucleated, unbranched fibers. Skeletal muscles are composed of skeletal muscle tissue, nervous tissue, blood, and connective tissue. The control of this muscle is voluntary. These muscles do contain sarcomeres, transverse tubules, but do not have gap junctions.


The cardiac muscles are located in the heart. They appear to be striated uninucleated, branched fibers with intercalated discs. The control of this muscle is involuntary. They contain sarcomeres, transverse tubules and also gap junctions. The smooth muscles are located in the walls of hollow viscera, blood vessels, iris, and in the arrector pili. They appear to be nonstriated, uninucleated, spindle-shaped fibers. The control of the muscle is involuntary. They do not contain sarcomeres, or transverse tubules. They do contain gap junctions (in visceral smooth muscle). There are two major types of smooth muscle tissue: multiunit and visceral. In multiunit smooth muscle, the muscle fibers are separate rather than organized intProxy-Connection: keep-alive CacheProxy-Connection: keep-alive Cache-Control: max-age=0 oxy-Connection: keep-alive Cache-Control: max-age=0 oxy-Connection: keep-alive Cache-Control: max-age=0 oxy-Connection: keep-alive Cache-Control: max-age=0 ontrol: max-age=0 20sheets. Typically, multiunit smooth muscle tissue contracts only in response to stimulation by motor nerve impulses or certain hormones. Visceral or smooth muscle is composed of sheets of spindle-shaped cells in close contact with one another. This is the more common type of smooth muscle.


Fibers of these are stimulate each other. When one fiber is stimulated, the impulse moving over its surface may excite adjacent fibers, which, in turn, stimulate still others. Visceral smooth muscles also display rhythmicity в a pattern of repeated contractions. Rhythmicity is due to self-exciting fibers that deliver spontaneous impulses periodically into surrounding muscle tissue. These two features в transmission of impulses from cell to cell and rhythmicity в are largely responsible for the wavelike motion, called peristalsis. We need muscles to move, both voluntarily and to carry out body functions, like digestion. Without muscles, most of the life that we see around today would not exist because many of the body functions in animals would never have been able to occur. We need three different kinds of muscles because they all do different things. If all muscles were voluntary skeletal ones, we could easily die if we forgot to pump our hearts, breath, carry out digestion, and do many of the other critical functions carried out by involuntary muscles. Likewise, if all were involuntary, we would not be able to move of our own will. Muscles are not only involved in the movement of muscles but they are important in making sure that the same body parts do not move. Muscles always maintain a state of partial contraction.


These partial contracted muscles push against each other in equal amounts to insure that no net movement of a body part or bone. Without these muscles we would not be able to maintain a stationary position
This simple demonstration answers the question of why the human body needs both muscles and bones. This is a great introduction for young children to the various systems in our bodies and how they work together. This activity was inspired by (which we checked out from our library). Our boys were especially excited about this experiment because it involved eating two of their favorite things: pancakes and cookies. :) Here s what you ll need for this demonstration: a pancake and a gingerbread man (or overcooked sugar cookie). The pancake illustrates what our muscles are like bendable but can t hold anything up. The cookie demonstrates what our bones are like: strong but stiff. Our bones are strong and hold our bodies up (just like the cookie is able to stand upright without falling to the ground). But out muscles are bendable and allow us to move. When you try to move bones (without muscles), they can t move much without snapping in half. Oops. What other ways have you found to explain to children why we need both muscles and bones? * Also, be sure to check out! *

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