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28 Cards in this Set
- Front
- Back
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What is the size and characteristics of a skeletal muscle?
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A skeletal muscle is relatively large and contains many nuclei located asymmetrically near the plasma membrane.
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What is the sacroplasm?
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The sacroplasm is the cytoplasm of a skeletal muscle. It contains many mitochondria, a sacroplasmic reticulum, and myofibrils.
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What is a myofibril?
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A myofibril is the contracting unit found within the cell. They consist of a repeating unit called a sacromere.
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What is a sacromere?
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A sacromere is a repeating unit found in skeletal muscles. It consists of two types of filaments: thich and thin filaments
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What is a thick filament?
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A thick filament is associated with the "A band" of the sacromeric unit.
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How are the myosin molecules arranged in a thick filament?
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The myosin molecules are arranged in the thick filament so that the head structures project outward, forming cross-bridges to the thin filaments, and the the tails are all bundled together, forming the body of the filament (tails all point toward the mid-point of the shaft of the filament)
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How many thick filaments surround a thin filament?
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3 thick filaments surround 1 thin filament
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What is a thin filament?
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Thin filaments are associated with the "I band" of the sacromeric unit.
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What are thin filaments composed of?
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Thin filaments are composed of three proteins: G-actin, troponin, tropomysosin.
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How many thin filaments surround a thick filament?
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6 thin filaments surround 1 thick filament
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What is the A Band?
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-anisotropic band
-a region indicating the length of myosin -the darker region of the A band contain the ends of the actin filaments and myosin. |
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What is the I Band?
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-isotrophic band
-a region containing only actin -there is no overlapping of actin by myosin |
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What is the H Band?
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-a region in the cneter of a relaxed sacromere where the thick filaments are not overlapped by thin filaments
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What is the Z line?
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-the structure to which the actin filaments attach
-two Z lines bound the sacromere |
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What is the M line?
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-a line passing transversely through the middle of the H Band.
-Produced due to a central bulge in each thick filaments and slender interconnections that hold the filaments in position. |
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What is muscle contraction?
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The process by which the muscle cell contracts is brought about by the sliding of thin filaments along thick filaments.
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What are tendons?
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Tendons are fibrous connective tissue cords or sheets which connect muscle to bone. Generally they are an extension of the epimysium, endomysium, and permysium.
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What are tendons of origin?
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A tendon of orgins is the tendon attaching to the proximal, less movable bone at a joint.
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What are tendons of insertion?
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A tendon of insertion is the tendon attaching to the distal, morer movable bone at a joint.
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What is a aponeuroses?
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It is a broad, flat, sheet-like tendon.
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What is a tendon (synovial) sheath?
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Some tendons are enclosed with a fibrous connective tissue called a tendon sheath. They permit the tendon to slide freely.
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Why are tendons importnat?
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Tendons are important becuase they concentrate the force of a muscle on a single point and tendons make it possible for a muscle to be situated at a distance from its point of action. This permits versatility of action, yet allows great strength.
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Blood and lymphatic supply to muscles:
Define Fascicles |
-Fascicles are buncles of cells surrouned by perimysium
-They are penetrated by vessels which follow perimysial invaginations called trabeculae |
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Blood and lymphatic supply to muscles:
How many arteries and veins are associated with a muscle? |
One artery and two veins are associated with a muscle
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Nerve supply to muscles:
What are sensory nerves? |
Sensory nerves are described as afferent nerves which arise from specialized muscle cells called muscle spindles and carry impulses to the central nervous system
-they are stimulated by muscle stretch and make one aware of muscle status |
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Nerve supply to muscles:
What are motor nerves? |
-Motor nerves are described as efferent nerves which arise in the central nervous system and carry impulses to muscles.
-There are two types of motor nerves: alpha motor neurons and gamma motor neurons |
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Nerve supply to muscles:
What are alpha motor neurons? |
-neurons which end at neuromuscular junctions of regular muscle fibers and stimulate them to activity
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Nerve supply to muscles:
What are gamma motor neurons? |
-neurons which end at neuromuscular junctions of muscle spindle and control their reactivity
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