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Explore the diverse functions of muscles, from facilitating body movements to pumping blood and moving food through the digestive system. Learn about skeletal, smooth, and cardiac muscle tissues, their characteristics, and how muscle contraction occurs. Dive into fascinating facts about muscles and their significance in the human body.
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Functions • All body movements • Moves bones • Pumps blood • Move food through digestive system • Air movement
Types of Muscle Tissue 1) Skeletal Muscles • Responsible for voluntary movements • Skeletal movements • Striated (alternating light and dark bands)
Skeletal Muscle, cont’d Myofibrils Muscle Fibers Actin (thin filaments) & Myosin (thick filaments)
Types of Muscle Tissue 2) Smooth Muscle • Involuntary • Found in intestines and blood vessels • Move food through intestines through peristalsis
Types of Muscle Tissue • Cardiac Muscle • Involuntary • Striatedw/centrally located nuclei • Found in Heart • Never gets tired
Muscle Contraction • Thin filaments (Actin) in the muscle fiber slide over the thick filaments (Myosin) to contract the muscle • Muscle fibers contracting • Cardiac muscle contracting
Cardiac Muscle How would you characterize this muscle? The nuclei are centrally located, striations are present, and there is branching of the muscle fibers. Several intercalated discs are indicated by the white arrow heads. In Virtual Microscopy, look in the upper left corner of the section to find longitudinally cut fibers.
Skeletal Muscle How would you characterize this muscle? The nuclei are peripheral, striations are present, and there is no branching of the muscle fibers. Even when you cannot visualize striations, the peripherally placed nuclei allow you to differentiate skeletal muscle from both cardiac and smooth muscle.
Smooth Muscle How would you characterize this muscle?The nuclei are centrally located, there are no striations, and the musclefibers do not branch. Another good clue that this is smooth muscle is that when smooth muscle contracts, the nuclei take on a corkscrew appearance.
Muscle Tone • Skeletal muscles remain in a state of partial contraction • Responsible for keeping head upright, and your back and legs straight
Antagonistic Relationship • Skeletal muscles work in opposing pairs • When one muscle contracts, the other relaxes • Example of antagonistic relationship: biceps/triceps
Interesting Facts • Muscles make up about 40% of a male’s weight and about 35% if you are female • The largest muscle in your body is the gluteus maximus • Muscular strength reaches its peak between the ages of 20 and 30