Term
| Three types of muscle tissue |
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Definition
| Skeletal, cardiac, and smooth |
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Term
| Differences between types of muscle tissue |
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Definition
| Structure, location, function, means of activation |
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Term
| Skeletal and smooth muscle cells are elongated and are called _____ |
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Definition
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Term
| Muscle contraction depends on two kind of myofilaments, _____ |
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Definition
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Term
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Definition
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Term
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Definition
| cytoplasm of a muscle cell |
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Term
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Definition
| myo, mys, and sacro all refer to muscles |
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Term
| Skeletal Muscle Tissue: Basics |
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Definition
| Packaged in skeletal muscles that attach to and cover the bony skeleton. Has obvious stripes called striations. Controlled voluntarily. Contracts rapidly but tires easily. Response for overall body motility. Extremely adaptable and can exert forces ranging from a fraction of an ounce to over 70 lbs |
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Term
| Cardiac Muscle Tissue: Basics |
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Definition
| Occurs only in the heart. Striated like skeletal muscle but is not voluntary. Contracts at a fairly steady rate set by the heart's pacemaker. Neural controls allow the heart to respond to changes in bodily needs |
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Term
| Smooth Muscle Tissue: Basics |
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Definition
| Found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages. Forces food and other substances through internal body channels. It is not striated and is involuntary |
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Term
| Functional characteristics of Muscle Tissue |
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Definition
| Excitability/Irritability, Contractility, Extensibility, Elasticity |
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Term
| Functional Characteristics of Muscle Tissue: Excitability/Irritability |
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Definition
| The ability to receive and respond to stimuli |
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Term
| Functional Characteristics of Muscle Tissue: Contractility |
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Definition
| The ability to shorten forcibly |
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Term
| Functional Characteristics of Muscle Tissue: Extensibility |
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Definition
| The ability to be stretched or extended |
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Term
| Functional Characteristics of Muscle Tissue: Elasticity |
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Definition
| The ability to recoil and resume the original resting length |
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Term
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Definition
| Responsible for all locomotion |
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Term
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Definition
| responsible for coursing the blood through the body |
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Term
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Definition
| helps maintain blood pressure, and squeezes or propels substances (food,feces) through organs |
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Term
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Definition
| Maintain posture, stabilize joints, and generate heat |
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Term
| Skeletal muscle composition |
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Definition
| Muscle tissue, blood vessels, nerve fibers, and connective tissue |
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Term
| Three connective tissue sheaths |
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Definition
| Endomysium, Perimysium, Epimysium |
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Term
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Definition
| Fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber |
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Term
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Definition
| Fibrous connective tissue that surrounds groups of muscle fibers called fasicles |
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Term
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Definition
| an overcoat of dense regular connective tissue that surrounds the entire muscle |
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Term
| Skeletal Muscle: Nerve and Blood Supply |
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Definition
Each muscle is served by one nerve, an artery , and one or more veins.
Each skeletal muscle fiber is supplied with a nerve ending that controls contraction
Contracting fibers require continuous delivery of oxygen and nutrients via arteries
Wastes must be removed via veins |
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Term
| Skeletal Muscle: Attachments |
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Definition
Most skeletal muscles span joints and are attached to bone in at least two places
When muscles contract the movable bone, the muscle's insertion moves toward the immovable bone, the muscle's origin |
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Term
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Definition
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Term
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Definition
| epimysium of the muscle is fused to the periosteum of the bone |
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Term
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Definition
| connective tissue wrappings extend beyond the muscle as a tendon or aponeurosis |
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Term
| Microscopic Anatomy of a Skeletal Muscle Fiber |
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Definition
Each fiber is a long, cylindrical cell with multiple nuclei just beneath the sarcolemma.
Fibers are to 10 to 100 um in diameter, and up to hundreds of centimeters long
Sarcoplasm has a unique oxygen-binding protein called myoglobin
Fibers contain the usual organelles, myofibrils, sarcoplasmic reticulum, and T tubules |
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Term
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Definition
| Densely packed, rodlike contractile elements. Make up most of the muscle volume. Arrangemet of myofibrils with a fiber is such that perfect aligned repeating series of dark A band and light I bands is evident |
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Term
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Definition
| Smallest contractile unit of a muscle. The region of a myofibril between two successive Z discs. Composed of myofialments made up of contractile proteins. |
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Term
| Two types of myofilaments |
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Definition
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Term
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Definition
| area of myosin/actin overlap |
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Term
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Definition
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Term
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Definition
| area of actin filaments - no myosin |
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Term
| I band: composed of what? |
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Definition
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Term
| Myofilaments: Banding pattern |
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Definition
Thick (myosin) filaments - extend the entire length of an A band
Thin (actin) filaments - extend across the I band and partway into the A band
Z-disc: coin-shaped sheet of proteins (connectins) that anchors the thin filaments and connects myofibrils to one another |
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Term
| Actin: Thick or thin filament? |
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Definition
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Term
| Myosin: Thick or thin filaments? |
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Definition
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Term
| Do thin filaments overlap thick filaments in the lighter H zone? |
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Definition
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Term
| Ultrastructure of Myofilaments: Thick Filaments |
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Definition
| Thick filaments are are composed of the protein myosin. Each myosin molecule has a rod-like tail and two globular heads. |
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Term
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Definition
| two interwoven, heavy polypeptide chains |
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Term
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Definition
| Two, smaller, light polypeptide chains called cross bridges |
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Term
| Ultrastructure of Myofilaments: Thin filaments |
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Definition
Thin filaments are chiefly composed of the protein actin. Each actin molecule is a helical polymer of globular subunits called G actin. The subunits contain the active sites to which myosin heads attach during contracting (actin/myosin cross bridge)
Tropmyosin and troponin are regulatory subunites bounds to actin |
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Term
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Definition
An elaborate, smooth endoplasmic reticulum that most runs longitudinally and surrounds each myofibril
Paired terminal cisternae form perpendicular cross channels
Functions in the regulation of intracellular calcium levels |
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Term
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Definition
| Elongated tubes called T tubules penetrate into the cell's interior at each A band-I band junction. T Tubules associate with the paired terminal cisternae (pools) to form triads |
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Term
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Definition
Continuous with the sarcolemma
Conduct impulses to the deepest regions of the muscle
These impulses signal for the release of Ca2+ from adjacent terminal cisternae (pools) |
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Term
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Definition
T tubules and SR provide tightly linked signals for muscle contraction. A double zipper of integral membrane proteins protrudes into the intermembrane space. T tubules proteins act as voltage sensors
SR foot proteins are receptros that regulate Ca2+ release from the SR cisternae |
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Term
| Sliding Filament Model of Contraction - Short Story |
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Definition
Thin filaments slide past the thick ones so that the action and myosin filaments overlap to a greater degree.
In the relaxed state, thin and thick filaments overlap only slightly
Upon stimulation, myosin heads bind to actin and sliding begins.
Each myosin head binds and detaches several times during contraction, acting like a ratchet to generate tension and propel the thin filaments to the center of the sarcomere.
As this event occurs throughout the sarcomeres, the muscle shortens |
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Term
| Skeletal Muscle Contraction: In order to contract a skeletal muscle must... |
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Definition
Be stiumalted by a nerve ending, propagate an electrical current, or action potential, along its sarcolemma, have a rise in intracellular Ca2+ levels, the final trigger for contraction.
Linking the electrical signal to the contraction is excitation-contraction coupling |
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Term
| Nerve Stimulus of a Muscle Cell |
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Definition
| Skeletal muscles are stimulated by motor neurons of the somatic nervous system. Axons of these neurons travel in nerves to muscle cells. Axons of motor neurons branch profusely as they enter muscles. Each axonal branch form a neuromuscular junction with a single muscle fiber |
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Term
| Neuromuscular junction: Formation |
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Definition
| Axonal endings which have small membranous sacs (synaptic vesicles) that contain the neurotransmitter acetylcholine (ACh). The motor end plate of a muscle, which is a specific part of the sarcolemma that contains ACh receptors and helps form the junction |
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Term
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Definition
| Space between axonal ends and muscle fibers of the neuromuscular junction |
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Term
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Definition
| Space between axonal ends and muscle fibers of the neuromuscular junction |
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Term
| When a nerve impulse reaches the end of an axon at the the neuromuscular junction....: what happens? |
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Definition
Voltage-regulated calcium channels open and allow Ca2+ to enter the axon.
Ca2+ inside the axon terminal causes axonal vesicles to fuse with the axonal membrane
This fusion release ACh into the synaptic cleft via exocytosis
ACh diffuses across the synaptic cleft to ACh receptors on the sarcolemma
Binding of ACh to its receptors initiates an action potential in the muscle |
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Term
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Definition
Binds its receptors at the motor end plate
Binding opens chemically (ligand) gated channels
Na+ and K+ diffuse out and the interior of the sarcolemma becomes less negative |
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Term
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Definition
ACh bound to ACh receptors is quickly destroyed by the enzyme acetycholinesterase
This destruction prevents continued muscle contraction in the absence of additional stimuli |
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Term
| Organizatonal level of muscle: Surface to Deep |
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Definition
| Organ > Fasicle > Cell > Myofibril/Fibril > Sarcomere > Myofilament/Filament |
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Term
| Muscle Organ: Description |
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Definition
| Consists of hundreds to thousands of muscle cells, plus, connective tissue wrappings, blood vessels, and nerve fibers |
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Term
| Muscle organ: Connective tissue wrappings |
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Definition
| Covered externally by the epimysium |
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Term
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Definition
| Discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath. |
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Term
| Fascicle: Connective tissue wrappings |
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Definition
| Surrounded by a perimysium |
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Term
| Muscle fiber (Cell): Description |
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Definition
| Elongated multinucleate cell; has a banded (striated) appearance |
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Term
| Muscle fiber (Cell): Connective Tissue Wrappings |
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Definition
| Surrounded by the endoysium |
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Term
| Myofibril/fibirle: description |
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Definition
| complex organelle composed of bundles of myofilaments. rodlike contractile elements; myofibrils occupy most of the muscle cell volume; composed of sarcomeres arranged end to end; appears banded, and bands of adjacent myofibrils are aligned |
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Term
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Definition
| a segment of myofibril. The contractile unit, composed of myofilaments made up of contractile proteins |
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Term
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Definition
| Extended macromolecular structure. contractile myofilaments are of two types - thick and thin. The thick filaments contain bundled myosin molecules; the thin filaments contain actin molecules; the sliding of the thin filaments past the thick filaments produces muscle shortening. Elastic filaments maintain the organization of the A band and provide for elastic recoil when muscle contraction ends |
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Term
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Definition
| A transient depolarization event that includes polarity reversal of a sarcolemma (or nerve cell membrane) and the propagation of an action potential along the membrane |
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Term
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Definition
Initially, this is a local electrical event called end plate potential
Later, it ignites an action potential that spreads in all direction across the sarcolemma |
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Term
| Excitation-Contraction Coupling: Once generated, the action potential... |
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Definition
Is propagated along the sarcolemma.
Travels down the T tubules
Triggers Ca2_ release from terminal cisternae |
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Term
| Ca2+ release from terminal cisternae causes... |
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Definition
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Term
| Ca2+ binding to troponin causes... |
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Definition
The clocking action of tropomyosin to cease
Actin active binding sites to be exposed |
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Term
| Excitation-Contraction Coupling: Post Ca2+ binding... |
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Definition
Myosin cross bridges alternately attach and detach
Thin filaments move toward the center of the sarcomere
Hydrolysis of ATP powers this cycling process
Ca2+ is removed into the SR, tropomyosin blockage is restored, and the muscle fiber relaxes |
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Term
| Excitation-Contraction Coupling Summary: Step 1 |
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Definition
| Action potential generated and propagated along sarcomere to T-tubules |
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Term
| Excitation-Contraction Coupling Summary: Step 2 |
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Definition
| Action potential triggers Ca2+ release |
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Term
| Excitation-Contraction Coupling Summary: Step 3 |
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Definition
| Ca2+ bind to troponin; blocking action of tropomyosin released |
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Term
| Excitation-Contraction Coupling Summary: Step 4 |
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Definition
| Contraction via crossbrdige formation; ATP hydrolysis |
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Term
| Excitation-Contraction Coupling Summary: Step 5 |
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Definition
| Removal of Ca2+ by active transport |
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Term
| Excitation-Contraction Coupling Summary: Step 6 |
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Definition
| Tropomyosin blockage restored; contraction ends |
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Term
| Sequential Events of Contraction |
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Definition
Cross bridge formation: myosin cross bridge attaches to actin filament
Working (power) stroke: myosin head pivots and pulls actin filament towards M line
Cross bridge detachment: ATP attaches to myosin head and the cross bridge detaches
"Cocking" of the myosin head - energy from hydrolysis of ATP cocks the myosin head into the high-energy state |
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Term
| Contraction of Skeletal Muscle Fibers |
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Definition
Contraction - refers to the activation of myosin's cross bridges (Forge-generating sites)
Shortening occurs when the tension generated by the cross bridge exceeds forces opposing shortening
Contraction ends when cross bridges become inactive, the tension generated declines and relaxation is induced |
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Term
| Contraction of Skeletal Muscle (organ level) |
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Definition
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Term
| Two types of muscle contractions |
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Definition
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Term
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Definition
| increasing muscle tension (muscle does not shorten during contraction) |
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Term
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Definition
| decreasing muscle length (muscle shortend during contraction) |
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Term
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Definition
The nerve-muscle functional unit. A motor neuron and all the muscle fibers it supplies
The number of fibers per motor unit can vary from four to several hundred |
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Term
| Motor Unit: Small motor units |
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Definition
| For muscles that control fine movements (fingers, eyes) |
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Term
| Motor Unit: Large motor units |
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Definition
For large weight-bearing muscles (thighs, hips) have large motor units
Muscle fibers from a motor unit are spread throughout the muscle; therefore, contraction of a single motor unit causes weak contraction of the entire muscle |
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Term
| Muscle Twitch: What is it? |
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Definition
| the response of a muscle to a single, brief threshold stimulus |
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Term
| Muscle Twitch: Three phases |
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Definition
| Latent period, Period of contraction, Period of relaxation |
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Term
| Muscle Twitch: Latent period |
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Definition
| Events of excitation-contraction coupling |
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Term
| Muscle Twitch: Period of contraction |
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Definition
| cross bridge formation; tension increases |
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Term
| Muscle Twitch: Period of relaxation |
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Definition
| Ca2+ reentry into the SR; tension declines to zero |
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Term
| Muscle Twitch phases: Timing |
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Definition
Shortest to Longest
Latent > Contraction > Relaxation |
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Term
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Definition
| Type I, Type IIa, Type IIb |
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Term
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Definition
| Red muscle, slow, marathon |
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Term
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Definition
| Red muscle, fast, middle distance |
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Term
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Definition
| White muscle, fast, sprint |
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Term
| Type I muscle fiber characteristics |
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Definition
Do not get fatigued, can be used for hours
High mitochondrial and myoglobin count
High capillary desnity
Major fuel - tryglycerides |
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Term
| Type IIa muscle fibers characteristics |
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Definition
Can be fatigued but not to a great extent
Major fuel - creatine phosphate and glycogen |
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Term
| Type IIb muscle fibers characteristics |
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Definition
Major fuel - creatine phosphate and glycogen
Opposite of Type I |
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Term
| Muscle Fatigue: What is it? |
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Definition
| Physiological inability to contract |
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Term
| Muscle Fatigue: Occurs when? |
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Definition
Ionic imbalances (K+, Ca2+, P) interfere with E-C coupling
Prolonged exercise damages the SR and interferes with Ca2+ regulation and release
Total lack of ATP occurs rarely, during states of continous contractions, and causes contractures |
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Term
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Definition
| Extra O2 needed after exercise for replenishment of oxygen reserves, glycogen stores, ATP and CP reserves. Conversion of lactic acid to pyruvic acid, glucose, and glycogen. |
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