Chapter 10 Flashcards
Also has crossed radiation and easy law is composed of elongated often branch cells bound to one another at structures called intercalated disks that are unique to this muscle. contraction is involuntary vigorous and rhythmic
Cardiac muscle
Contains bundles of very long multinucleated cells with cross striations their contraction is quick forceful and usually under voluntary control
Skeletal muscle
Consist of collections of fusiform cells that lack striations and have slow involuntary contractions
Smooth muscle
In all types of muscle contraction is caused by the sliding interaction of thick_________ filaments along thin ______ filaments
Myosin, Actin
The cytoplasm of the muscle
Sarcoplasm
The smooth ER in muscle
Sarcoplasmic reticulum
The muscle cell membrane and its external Lamina
Sarcolemma
The variation in diameter of muscle fibers depends on factors such as the___________,____________,_______,_______, and __________
Specific muscle, age, gender, nutritional status, and physical training
Increased cell volume is called
Hypertrophy
Increase in number of cells is called
Hyperplasia
Have a small population and remains adjacent to most fibers of differentiated skeletal muscle
Satellite cells
An external sheath of dense connective tissue that surrounds the entire muscle septa of this tissue extend inward carrying larger nerves, blood vessels, and lymphatics of the muscle
Epimysium
A thin connective layer that immediately surrounds each bundle of muscle fibers ( fascicles) Nerves, blood vessels and lymphatics penetrate this layer to supply each fascicle
Perimysium
Surrounds the external lamina of individual muscle fibers.
Endomysium
Transitional regions where collagen fibers from the tendon insert themselves among muscle fibers and associate directly with complex Infoldings of sarcolemma
Myotendinous junctions
Dark bands where both actin and myosin are both present
A Bands
Light bands were actin filaments are present are bisected by the z disc
I bands
The repetitive functional subunit of the contractile apparatus
Sarcomere
Long cylindrical filament bundles , runs parallel to the long axis of the fiber
Myofibrils
Skeletal muscle mesenchymal cells
Myoblasts
When myoblasts Fuse to make multi-nucleated tubes
Myotubes
When myoblasts do not fuse and differentiate but remain a group of mesenchymal cells located on the external surface of muscle fibers inside developing external Lamina they proliferate and produce new muscle fibers following muscle injury
Satellite cells
Filaments or 1.6 µm long and 15 nm wide. It is a Marge complex with two identical heavy chains and two pairs of light chains heavy chains are thin rodlike motor proteins twisted together as tails
Myosin
Thin helical filaments which are one micrometer long 8 nm wide and run between the thick filaments contains a binding site for myosin
Actin
Acting filaments are anchored perpendicularly it on the Z disc by the actin binding protein
a-actin
A 40 nm long coil of two polypeptide chains located in the groove between the two twisted acting strands
Tropomyosin
This regulatory protein has three subunits ( TnT, TnC, TnI)
Tropnin
TnT of tropnin
Attaches to tropomyosin
TnC of Tropnin
Binds to Calcium
TnI in Tropnin
Regulates the actin-myosin interaction
The largest protein in the body with scaffolding and elastic properties which supports the thick myofilaments and connects them to the Z disc
Titin
A very large accessory protein binds eats then myofilaments latterly helps anchor them to Alpha Actin and specifies the links of the actin polymers During myogensis
Nebulin
Located in the M line
Holds thick filaments in place and is also a myosin binding protein
Myomesin
This enzyme catalyzes transfer of phosphate groups from phosphocreatine a storage form of high-energy phosphate groups to ADP helping to supply ATP for muscle contraction
Creatine kinase
Is specialized for calcium Sequestration
Sacroplasmic reticulum
______________ of the sarcoplasmic reticulum membrane which causes release of calcium is initiated at specialized motor nerve synapses on the sarcolemma
Depolarization
Long fingerlike invagination’s of the cell membrane penetrate deeply into the sarcoplasm and encircle every myofibril near the aligned A and I and boundaries of sarcomeres
Transverse or T tubules
Adjacent to each side of every T tubule are expanded
Terminal cisterns
The complex of a T tubule with 2 associated small cisterns of sarcoplasmic reticulum on each side is known as
A Triad
When each axonal branch forms a dilated termination situated within a trough on the muscle cell surface
Motor end plate ( neuromuscular Junction)
What removes excess neurotransmitter ?
Acetylcholinesterase
A single axon and all the muscle fibers in contact with its branches make up a
Motor unit
Fibers of skeletal muscle are
Single multinucleate cells
Cell and fiber shape and size of skeletal muscle
Cylindrical 10 to 100 µm in diameter many centimeters long
Are there striations and skeletal muscle
Yes
Location of nuclei in skeletal muscle
Peripheral adjacent to sarcolemma
T tubules of skeletal muscle are located
Center of triads at A –I junctions
The sarcoplasm reticulum of skeletal muscle is
Will develops with two terminal cisterns per sarcomere and triads with T-tubule
Special structural features of skeletal muscle
Very well organized sarcomeres use SR, and tranverse tubule system
Control of contraction in skeletal muscle
troponin C binds calcium moving tropomyosin and exposing actin for myosin binding
Connective tissue organization for skeletal muscle
Endomysium Perimysium and epimysium
Major locations of skeletal muscle
Skeletal muscle tongue diaphragm eyes and upper esophagus
Key function of skeletal muscle
Voluntary Movement
Efferent innervation of skeletal muscle
Motor
Contractions in skeletal muscle
All-or-none triggered at motor in plates
Cell response to increased workload in skeletal muscle
Hypertrophy
Capacity for generation in skeletal muscle
Limited involving satellite cells mainlyp
In cardiac muscles fibers are
Aligned cells and branching arrangement
This cell and fiber shape and size of cardiac muscle
Cylindrical, 10-20 micrometers in diameter, 50-100 micrometers long
Are there striations in cardiac muscle
Yes
Location of nuclei in cardiac muscle
Central
T tubules in cardiac muscle
In do ads at Z discs
Sarcoplasmic reticulum in cardiac muscle
Less well developed one small terminal cistern per sarcomere in Diad with T tubule
Special structural features of cardiac muscle
Intercalated discs joining cell, with many adherent and gap junctions
Control of contraction in cardiac muscle
Troponin C binds Calcium, moving tropomyosin and exposing actin for myosin binding
Connective tissue organization of cardiac muscle
Endomysium, subendocardial, and supericardial CT layers
Major locations of cardiac muscle
Heart
Key function of cardiac muscle
Automatic ( involuntary) pumping of blood
Contractions of Cardiac muscle
All-or-none, intrinsic ( beginning at nodes of conducting fibers)
Cell response to increased workload in cardiac muscle
Hypertrophy
Capacity to regeneration in cardiac muscle
Very poor
Fibers of smooth muscle are
Single small closely packed fusiform cells
Cell and fiber shape and size of smooth muscle are
Fusiform diameter .2 to 10 µm length 50- 200 µm
Striations in smooth muscle?
Absent
Location of nuclei in smooth muscle
Central, say widest part of cell
T tubules of smooth muscle
Absent; caveolae may be functionally similar
Sarcoplasmic reticulum of smooth muscle
Irregular smooth ER without distinctive organization
Special structural features in smooth muscle
Gap junctions, caveolae, dense bodies
Control of contraction in smooth muscle
Actin-Myosin binding occurs with myosin phosphorylation by MLCK triggered when calmodulin binds calcium
Connective tissue organization in smooth muscle
Endomysium and less organized CT sheaths
Major locations in smooth muscle
Blood vessels, digestive and respiratory tracts, uterus, bladder, and other organs
Key functions in smooth muscle
Involuntary movements
Efferent innervation in smooth muscle is
Autonomic
Contractions in Smooth muscle
Partial, slow, often spontaneous, wavelike and rhythmic
Cell response to increased load in smooth muscle
Hypertrophy and hyperplasia ( increase in cell/ fiber numbers)
Capacity for regeneration in smooth muscle
Good, involving mitotic activity of muscle cells
Slow oxidative fibers (type one) are ________in mitochondria and capillaries
Numerous
Repair and regeneration can occur in __________muscle because of a population of reserve muscle ______________cells that can proliferate use inform you must of fibers
Skeletal ,Satellite
Cardiac muscle Lacks_____________ cells and has little capacity for regeneration
Satellite
Regeneration is rapid in _________muscle because the cells \fibers are small and relatively less differentiated which allow renewed __________ activity after injury
Smooth, mitotic
Benign tumors called ______, commonly develop from smooth muscle fibers but are seldom problematic they most frequently occurring the wall the users with them, commonly called ________ where they can become sick sufficiently large to produce painful pressure and unexpected bleeding
Leiomyomas, fibroids
The most common injuries sustained by cardiac muscle is that due to _______ or tissue damage due to lack of oxygen when coronary arteries are occluded by heart disease
Ischemia
Research on the possibility possibility of the mammalian ______ _______ _______Builds on work with animal models focusing primarily on the potential for mesenchymal stem cells to form new site specific muscle
Heart muscle regeneration
__________is a large actin binding protein located just inside the sarcolemma of skeletal muscle fibers which is involved in the functional organization of myofibrils
Dystrophin
Research on _________ revealed that mutations of the dystrophin gene can lead to defective linkage linkages between the cytoskeleton and the ECM muscle contractions Can disrupt these weak link linkages causing the Atrophy of muscle fibers typical of this disease
Duchenne muscular dystrophy
______________ is a autoimmune disorder that involves circulating antibodies against proteins of acetylcholine receptors
Myasthenia Gravis
Increase in cell volume
Hypertrophy
Increase in the number of cells
Hyperplasia