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. Generally speaking, skeletal muscle is grouped into opposing pairs such as the biceps and triceps on the front and back of the upper arm. Skeletal muscles are under our conscious control, which is why they are also known as voluntary muscles. Another term is striated muscles, since the tissue looks striped when viewed under a microscope. Smooth muscle — located in various internal structures including the digestive tract, uterus and blood vessels such as arteries.
Smooth muscle is arranged in layered sheets that contract in waves along the length of the structure. Another common term is involuntary muscle, since the motion of smooth muscle happens without our conscious awareness.
Cardiac muscle — the muscle specific to the heart. The heart contracts and relaxes without our conscious awareness. Make-up of muscle Skeletal, smooth and cardiac muscle have very different functions, but they share the same basic composition. A muscle is made up of thousands of elastic fibres bundled tightly together. Each bundle is wrapped in a thin transparent membrane called a perimysium. An individual muscle fibre is made up of blocks of proteins called myofibrils, which contain a specialised protein myoglobin and molecules to provide the oxygen and energy required for muscle contraction.
This includes the beating of the heart and the movement of food through the digestive system. The muscular system is closely associated with the skeletal system in facilitating movement. Both voluntary and involuntary muscular system functions are controlled by the nervous system. The muscular system : Skeletal muscle of the muscular system is closely associated with the skeletal system and acts to maintain posture and control voluntary movement. Muscle is a highly-specialized soft tissue that produces tension which results in the generation of force.
Muscle cells, or myocytes, contain myofibrils comprised of actin and myosin myofilaments which slide past each other producing tension that changes the shape of the myocyte. Numerous myocytes make up muscle tissue and the controlled production of tension in these cells can generate significant force. Muscle tissue can be classified functionally as voluntary or involuntary and morphologically as striated or non-striated.
Voluntary refers to whether the muscle is under conscious control, while striation refers to the presence of visible banding within myocytes caused by the organization of myofibrils to produce constant tension. Muscle tissue is characterized by properties that allow movement. Muscle cells are excitable; they respond to a stimulus.
They are contractile, meaning they can shorten and generate a pulling force. When attached between two movable objects, in other words, bones, contractions of the muscles cause the bones to move.
Some muscle movement is voluntary, which means it is under conscious control. For example, a person decides to open a book and read a chapter on anatomy. Other movements are involuntary, meaning they are not under conscious control, such as the contraction of your pupil in bright light.
Muscle tissue is classified into three types according to structure and function: skeletal, cardiac, and smooth Table 4. Skeletal muscle is attached to bones and its contraction makes possible locomotion, facial expressions, posture, and other voluntary movements of the body. Forty percent of your body mass is made up of skeletal muscle. 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.
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