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28 Cards in this Set

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What is the size and characteristics of a skeletal muscle?
A skeletal muscle is relatively large and contains many nuclei located asymmetrically near the plasma membrane.
What is the sacroplasm?
The sacroplasm is the cytoplasm of a skeletal muscle. It contains many mitochondria, a sacroplasmic reticulum, and myofibrils.
What is a myofibril?
A myofibril is the contracting unit found within the cell. They consist of a repeating unit called a sacromere.
What is a sacromere?
A sacromere is a repeating unit found in skeletal muscles. It consists of two types of filaments: thich and thin filaments
What is a thick filament?
A thick filament is associated with the "A band" of the sacromeric unit.
How are the myosin molecules arranged in a thick filament?
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)
How many thick filaments surround a thin filament?
3 thick filaments surround 1 thin filament
What is a thin filament?
Thin filaments are associated with the "I band" of the sacromeric unit.
What are thin filaments composed of?
Thin filaments are composed of three proteins: G-actin, troponin, tropomysosin.
How many thin filaments surround a thick filament?
6 thin filaments surround 1 thick filament
What is the A Band?
-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.
What is the I Band?
-isotrophic band
-a region containing only actin
-there is no overlapping of actin by myosin
What is the H Band?
-a region in the cneter of a relaxed sacromere where the thick filaments are not overlapped by thin filaments
What is the Z line?
-the structure to which the actin filaments attach
-two Z lines bound the sacromere
What is the M line?
-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.
What is muscle contraction?
The process by which the muscle cell contracts is brought about by the sliding of thin filaments along thick filaments.
What are tendons?
Tendons are fibrous connective tissue cords or sheets which connect muscle to bone. Generally they are an extension of the epimysium, endomysium, and permysium.
What are tendons of origin?
A tendon of orgins is the tendon attaching to the proximal, less movable bone at a joint.
What are tendons of insertion?
A tendon of insertion is the tendon attaching to the distal, morer movable bone at a joint.
What is a aponeuroses?
It is a broad, flat, sheet-like tendon.
What is a tendon (synovial) sheath?
Some tendons are enclosed with a fibrous connective tissue called a tendon sheath. They permit the tendon to slide freely.
Why are tendons importnat?
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.
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
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
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
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
Nerve supply to muscles:

What are alpha motor neurons?
-neurons which end at neuromuscular junctions of regular muscle fibers and stimulate them to activity
Nerve supply to muscles:

What are gamma motor neurons?
-neurons which end at neuromuscular junctions of muscle spindle and control their reactivity