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Questions and Answers
Muscle cells have the ability to react to a stimulation that a hormone or motor neuron may deliver, which is known as ______.
excitability
The epimysium is a dense ____________ tissue that encloses the entire skeletal muscle.
connective
Muscle tissue is responsible for ______ and movement of the different parts of the body.
locomotion
Muscle growth is caused by the formation of new ____________ and an increase in the diameter of individual muscle fibers.
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The perimysium wraps around each ____________ of muscle fibers.
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The ______ of muscle cells is the tendency to shorten significantly.
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The endomysium is a delicate layer that surrounds individual ____________ fibers.
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Skeletal muscle is composed of bundles of very long, cylindrical, ______ cells.
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Cardiac muscle has ______ and is composed of elongated, branched individual cells.
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Type I muscle fibers are also known as slow, ____________ fibers.
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Smooth muscle consists of collections of ______ cells that do not show striations.
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Type I muscle fibers generate energy primarily from ____________ phosphorylation of fatty acids.
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The ______ is the cytoplasm of muscle cells and fibers which is acid in staining.
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Type I muscle fibers are ____________-twitch, fatigue-resistant motor units.
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The velocity of the myosin ATPase reaction is the ____________ of all muscle fiber types in Type I fibers.
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Myofibrils are fine threadlike structures in the ______ which is responsible for muscle contraction.
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Myoblasts align and fuse together to make longer, multinucleated tubes called ______.
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Satellite cells are unfused myeloblasts population located on the external surface of muscle fibers inside the developing ______.
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Within the myofibrils are also SER-associated concentrations of ______ and glycogen.
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The ______ band is a darker band that is anisotropic.
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The Z line is a dark transverse line that bisects the ______ band.
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The sarcomere extends from Z line to Z line and is about ______ m long in resting muscle.
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F-actin is associated with ______ and troponin.
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Tropomyosin is a long, thin molecule about ______ nm in length.
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Thick filaments consist primarily of ______.
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The sarcolemma is highly folded to increase the number of ______ receptors at the NMJ.
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The muscle spindle is a specialized ______ receptor in muscle;
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The muscle spindle transmits information via ______ (afferent, Ia) nerve fibers to the central nervous system;
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Cardiac muscle has the same types and arrangement of ______ filaments as skeletal muscle;
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Cardiac muscle fibers exhibit ______ staining cross-bands, termed intercalated discs;
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Cardiac muscle cell has either one or two ______ located pale-staining nuclei;
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The structure and function of the ______ proteins in cardiac cells are essentially the same as in skeletal muscle;
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Mitochondria occupies ______ of the cytoplasmic volume;
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The tubules are more numerous and larger in cardiac muscle than in skeletal muscle and the ______ reticulum is less well developed;
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A localized injury to cardiac muscle tissue that results in the death of cells is repaired by replacement with ______ connective tissue.
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In smooth muscle cells, bundles of ______ and thick myofilaments crisscross obliquely through the membrane-lattice network.
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Thin filaments of smooth muscle cells lack ______ complexes and instead utilize calmodulin.
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Desmin is the major ______ filament protein in all smooth muscles.
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Vimentin is an additional component in ______ smooth muscle.
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Myosin light chain kinase (MLCK) is the enzyme that ______ myosin, which is required for myosin's interaction with F-actin.
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Cardiac function is lost at the site of ______ to cardiac muscle tissue.
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Myocardial Infarction is an example of a condition where ______ is used as a marker for diagnosis.
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Study Notes
Muscular Tissue
- Responsible for locomotion and movement of body parts
- Maintains posture and converts chemical energy to mechanical energy
- Produces heat in the body
General Characteristics
- Contractility: muscle cells can shorten significantly
- Extensibility: muscle's capacity to extend
- Elasticity: tendency to rebound upon contracting
- Excitability: ability to react to stimulation
- Unit structure: elongated shape, adapted for contraction
- Sarcoplasm: appears fibrillar due to myofibrils, acidophilic staining
- Cells bound together by areolar connective tissue containing blood vessels and nerves
- Myofilaments: responsible for muscle cell contraction, composed of actin and myosin II
Types of Muscle Tissue
- Skeletal muscle: composed of bundles of long, cylindrical multinucleated cells, shows cross-striations, contraction is quick, forceful, and under voluntary control
- Cardiac muscle: has cross-striations, composed of elongated, branched individual cells, contraction is involuntary, vigorous, and rhythmic
- Smooth muscle: consists of collections of fusiform cells, no striations, contraction is slow and not under voluntary control
Skeletal Muscle
- Muscle fibers: long, cylindrical multinucleated cells with diameters of 10–100 um
- Nuclei: long oval, usually found at the periphery of the cell under the cell membrane, helpful in distinguishing skeletal muscle from cardiac and smooth muscle
- Development: myoblasts align and fuse to form myotubes, which differentiate to form functional myofilaments and the nuclei are displaced against the sarcolemma
- Satellite cells: unfused myoblasts that proliferate and produce new muscle fibers following muscle injury
Muscle Fiber Types
- Classification: based on contractile speed, velocity of myosin ATPase reaction, and metabolic profile
- Type I or slow, red oxidative fibers: contain many mitochondria, abundant myoglobin and cytochrome complexes, slow-twitch, fatigue-resistant motor units
- A and I banding pattern: myofibrils, A bands are darker, I bands are lighter, Z line is a dark transverse line that bisects the I band
Thick Filaments
- Consist primarily of myosin, a large complex of two heavy chains and two pairs of light chains
- Myosin heavy chains: thin, rod-like molecules made up of two heavy chains twisted together as myosin tails
- Myosin heads: have ATP binding sites, ATPase activity, and the ability to bind actin
Sliding Filaments and Sarcomere Shortening in Contraction
- Events of muscle contraction: excitation, contraction, and relaxation
- Sarcomere shortening: sliding filaments, A bands get shorter, I bands get shorter, Z lines move closer together
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Description
Learn about the functions of muscular tissue, including locomotion, posture, and energy conversion, as well as its characteristics such as contractility, extensibility, and elasticity.
