Skeletal muscle mainly attaches to the skeletal system via tendons to maintain posture and control movement for example contraction of the biceps muscle, attached to the scapula and radius, will raise the forearm. Some skeletal muscle can attach directly to other muscles or the skin, as seen in the face where numerous muscles control facial expression. Skeletal muscle is under voluntary control, although this can be subconscious for example when maintaining posture or balance.
Morphologically skeletal myocytes are elongated and tubular and appear striated with multiple peripheral nuclei. Cardiac muscle tissue is found only in the heart where cardiac contractions pump blood throughout the body and maintain blood pressure. As with skeletal muscle cardiac muscle is striated, however it is not consciously controlled and so is involuntary. Cardiac muscle can be further differentiated from skeletal muscle by the presence of intercalated discs which control the synchronized contraction of cardiac tissues.
Cardiac myocytes are shorter than skeletal equivalents and contain only one or two centrally located nuclei. Smooth muscle tissue is found associated with numerous other organs and tissue systems such as the digestive system or respiratory system. It plays an important role in the regulation of flow in such tissues for example aiding the movement of food through the digestive system via peristalsis. Smooth muscle is non-striated, although it contains the same myofilaments they are just organized differently, and involuntary.
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Actions for this page Listen Print. Summary Read the full fact sheet. On this page. Different types of muscle Make-up of muscle The neuromuscular system Shapes of skeletal muscle Muscle disorders Where to get help Things to remember.
There are about muscles in the human body. Muscles have a range of functions from pumping blood and supporting movement to lifting heavy weights or giving birth. Muscles work by either contracting or relaxing to cause movement. This movement may be voluntary meaning the movement is made consciously or done without our conscious awareness involuntary.
Glucose from carbohydrates in our diet fuels our muscles. To work properly, muscle tissue also needs particular minerals, electrolytes and other dietary substances such as calcium, magnesium, potassium and sodium. A range of problems can affect muscles — these are collectively known as myopathy. Muscle disorders may cause weakness, pain or even paralysis. Different types of muscle The three main types of muscle include: Skeletal muscle — the specialised tissue that is attached to bones and allows movement.
Together, skeletal muscles and bones are called the musculoskeletal system also known as the locomotor system. Highly coordinated contractions of cardiac muscle pump blood into the vessels of the circulatory system. Similar to skeletal muscle, cardiac muscle is striated and organized into sarcomeres, possessing the same banding organization as skeletal muscle Figure 7.
However, cardiac muscle fibers are shorter than skeletal muscle fibers and usually contain only one nucleus, which is located in the central region of the cell. Cardiac muscle fibers also possess many mitochondria and myoglobin, as ATP is produced primarily through aerobic metabolism. Cardiac muscle fibers cells also are extensively branched and are connected to one another at their ends by intercalated discs.
An intercalated disc allows the cardiac muscle cells to contract in a wave-like pattern so that the heart can work as a pump. Smooth muscle so-named because the cells do not have striations is present in the walls of hollow organs like the urinary bladder, uterus, stomach, intestines, and in the walls of passageways, such as the arteries and veins of the circulatory system, and the tracts of the respiratory, urinary, and reproductive systems Figure 7.
Smooth muscle is also present in the eyes, where it functions to change the size of the iris and alter the shape of the lens; and in the skin where it causes hair to stand erect in response to cold temperature or fear. Although they do not have striations and sarcomeres, smooth muscle fibers do have actin and myosin contractile proteins, and thick and thin filaments.
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