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why do we need muscles in our 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
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? Why do we need muscles? Muscles are vital to the survival of all humans and animals.

The contraction of muscles allows the heart to beat from the early stages of life to the time of death without a single break. Muscle contractions also help generate body heat when needed, because of the large proportion of the body mass that it makes up. The active muscles release large amounts of heat and the blood transports heat to other tissues of the body for homeostasis. Other involuntary muscle contractions assist in the digestion of fluids and food. The primary function of muscle is to permit movement throughout the whole body. Without movement the purpose for living is nonexistent and futile. Why do we need 3 different kinds of muscles? Due to the complexity of the human body, three different types of muscle fibers are deemed necessary. A primary characteristic the three types of muscle tissues share is the ability to contract. The first type of muscle tissue is called skeletal muscle tissue. These groups of muscles can be controlled through conscious thinking. Therefore they are considered voluntary muscles. Facial expressions, writing, talking, chewing, sneezing, and dancing are just a few examples of skeletal muscle tissues at work. The ability to do what is considered simple, body movements is the skeletal musclesв doing. Smooth muscle tissue is the second type of muscle tissue. It lacks striations; hence the name. These muscles involuntarily contracts, and can be located in intestines, blood vessels, urinary bladders, uteruses, and stomachs. Peristalsis, a type of smooth muscle contraction, is a wave-like motion that helps push food through the digestive tract. This movement can also help contract blood vessels. Smooth muscle tissue serves the purpose of aiding in bodily functions. The third and final type of muscle fiber is cardiac muscle. The only location cardiac muscle is found is in the heart. The striated cells of cardiac tissue have a single nucleus, and join end-to-end. Intercalated disk is the term for the junction in which the cells meet. The main goal of the cardiac tissue is to allow the heart to continually beat without ever resting. Although if the heart is overworked, a heart attack occurs, and damage to the cardiac tissue is permanent.

Without the three different types of muscle tissue, the human body is limited in movement. Human life would definitely cease to exist without varied muscle tissue. Muscles can also be used for energy when we need it the most. When we burn all of our fats we can use it as backup energy, which has both negative and positive. Skeletal Muscles are anchored by tendons to bones and is used for moving and maintaining posture. Though this postural control is generally maintained as a subconscious reflex, the muscles responsible react to conscious control like non-postural muscles. An average adult male is made up of 40в50% of skeletal muscle and an average adult female is made up of 30в40%. Smooth Muscles are involuntary and are found within the walls of organs and structures such as the esophagus, stomach, intestines, uterus, urethra, bladder, blood vessels, and even the skin (in which it controls erection of body hair). Unlike skeletal muscle, smooth muscle is not under conscious control. Cardiac muscle is also an involuntary muscle but is more akin in structure to skeletal muscle, and is found only in the heart. Cardiac and skeletal muscles are striated in that they contain sarcomeres and are packed into highly-regular arrangements of bundles; smooth muscle has neither. While skeletal muscles are arranged in regular, parallel bundles, cardiac muscle connects at branching, irregular angles (called intercalated discs). Striated muscle contracts and relaxes in short, intense bursts, whereas smooth muscle sustains longer or even near-permanent contractions. What do they do for us? As a general overview, muscles produce movement (both voluntary and involuntary), help with our posture, and help to produce and maintain about 85% of our body heat. Red muscle: rich blood supply, many mitochondria (ATP), much myoglobin Contracts slowly, capable of long term activity without fatigue (slow twitch) White muscle: limited blood supply, few mitochondria, little myoglobin Capable of fast contractions and can develop great tension, fatigues quickly (fast twitch)

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