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17 Cards in this Set
- Front
- Back
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Properties of Muscle Tissue
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Excitability
respond to chemicals released from nerve cells Conductivity ability to propagate electrical signals over membrane Contractility ability to shorten and generate force Extensibility ability to be stretched without damaging the tissue Elasticity ability to return to original shape after being stretched |
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Functions of Muscle Tissue
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Producing body movements
Stabilizing body positions Regulating organ volumes bands of smooth muscle called sphincters Movement of substances within the body blood, lymph, urine, air, food and fluids, sperm Producing heat involuntary contractions of skeletal muscle (shivering) |
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Skeletal muscle
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attaches to bone, skin or fascia
striated with light & dark bands visible with scope |
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Cardiac muscle
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striated in appearance
involuntary control autorhythmic because of built in pacemaker |
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Smooth muscle
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attached to hair follicles in skin
in walls of hollow organs -- blood vessels & GI nonstriated in appearance involuntary |
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Superficial fascia
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loose connective tissue & fat underlying the skin
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Deep fascia
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dense irregular connective tissue around muscle
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Connective tissue components
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epimysium = surrounds the whole muscle
perimysium = surrounds bundles (fascicles) of 10-100 muscle cells endomysium = separates individual muscle cells |
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Nerve and Blood Supply
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Each skeletal muscle is supplied by a nerve, artery and two veins.
Each motor neuron supplies multiple muscle cells (neuromuscular junction) Each muscle cell is supplied by one motor neuron terminal branch and is in contact with one or two capillaries. nerve fibers & capillaries are found in the endomysium between individual cells |
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Fusion of Myoblasts into Muscle Fibers
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Every mature muscle cell developed from 100 myoblasts that fused together in the fetus (multinucleated).
Mature muscle cells can not divide (amitotic). Muscle growth is a result of cellular enlargement (Hypertrophy) & not cell division (Hyperplasis) Satellite cells retain the ability to regenerate new cells. |
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Muscle Fiber or Myofibers
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Muscle cells are long, cylindrical & multinucleated
Sarcolemma = muscle cell membrane Sarcoplasm filled with tiny threads called myofibrils & myoglobin (red-colored, oxygen-binding protein) |
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Sarcoplasmic Reticulum (SR)
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System of tubular sacs similar to smooth ER in nonmuscle cells
Stores Ca+2 in a relaxed muscle Release of Ca+2 triggers muscle contraction |
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Transverse Tubules
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invaginations of the sarcolemma into the center of the cell
filled with extracellular fluid carry muscle action potentials down into cell Mitochondria lie in rows throughout the cell near the muscle proteins that use ATP during contraction |
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Myofibrils & Myofilaments
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Muscle fibers are filled with threads called myofibrils separated by SR (sarcoplasmic reticulum)
Myofilaments (thick & thin filaments) are the contractile proteins of muscle |
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Proteins of Muscle
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contractile proteins
myosin and actin regulatory proteins which turn contraction on & off troponin and tropomyosin structural proteins which provide proper alignment, elasticity and extensibility titin, myomesin, nebulin and dystrophin |
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Filaments and the Sarcomere
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Thick and thin filaments overlap each other in a pattern that creates striations (light I bands and dark A bands)
The I band region contains only thin filaments. They are arranged in compartments called sarcomeres, separated by Z discs. In the overlap region, six thin filaments |
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Thick & Thin Myofilaments
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Supporting proteins (M line, titin and Z disc help anchor the thick and thin filaments in place)
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