Term
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Definition
•muscle cells are capable of converting the chemical energy of ATP into mechanical energy
•types of muscle
–skeletal, cardiac and smooth |
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Term
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Definition
-skeletal
-cardiac
-smooth |
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Term
| Characteristics of Muscle |
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Definition
•responsiveness (excitability)
•conductivity
•contractility
•extensibility
•elasticity |
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Term
| responsiveness (excitability) |
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Definition
| to chemical signals, stretch and electrical changes across the plasma membrane |
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Term
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Definition
| local electrical change triggers a wave of excitation that travels along the muscle fiber |
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Term
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Definition
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Term
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Definition
| capable of being stretched between contractions |
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Term
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Definition
| returns to its original resting length after being stretched |
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Term
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Definition
| voluntary, striated muscle attached to one or more bones |
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Term
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Definition
-alternating light and dark transverse bands
–results from an overlapping of internal contractile proteins
-organized in a precise way in skeletal and cardiac muscle |
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Term
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Definition
| attachments between muscle and bone matrix |
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Term
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Definition
| connective tissue around muscle cells |
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Term
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Definition
| connective tissue around muscle fascicles |
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Term
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Definition
| connective tissue surrounding entire muscle |
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Term
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Definition
–somewhat extensible and elastic
–stretches slightly under tension and recoils when released
•resists excessive stretching and protects muscle from injury
•returns muscle to its resting length |
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Term
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Definition
| plasma membrane of a muscle fiber |
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Term
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Definition
| cytoplasm of a muscle fiber |
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Term
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Definition
| long protein bundles that occupies the main portion of the sarcoplasm |
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Term
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Definition
| stored in abundance to provide energy with heightened exercise |
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Term
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Definition
| red pigment–stores oxygen needed for muscle activity |
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Term
| sarcoplasmic reticulum (SR) |
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Definition
-smooth ER that forms a network around each myofibril –calcium reservoir
–calcium activates the muscle contraction process |
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Term
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Definition
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Term
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Definition
–huge springy protein
–helps stabilize the thick filament
–center it between the thin filaments
–prevents over stretching |
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Term
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Definition
-contractile proteins
–do the work
–proteins that occur in all cells
–function in cellular motility, mitosis, transport of intracellular material |
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Term
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Definition
| -tropomyosin and troponin |
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Term
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Definition
–most clinically important
–genetic defects in _________ produce disabling disease muscular dystrophy |
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Term
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Definition
-functional contractile unit of the muscle fiber
-segment from Z disc to Z disc
–functional contractile unit of muscle fiber
•muscle cells shorten because their individual _________ shorten
•neither thick nor thin filaments change length during shortening |
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Term
| The Nerve-Muscle Relationship |
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Definition
•skeletal muscle never contracts unless stimulated by a nerve
•if nerve connections are severed or poisoned, a muscle is paralyzed
•denervation atrophy
•somatic motor neurons
•somatic motor fibers |
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Term
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Definition
| shrinkage of paralyzed muscle when connection not restored |
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Term
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Definition
| nerve cells whose cell bodies are in the brainstem and spinal cord that serve skeletal muscles |
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Term
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Definition
| their axons that lead to the skeletal muscle |
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Term
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Definition
| one nerve fiber and all the muscle fibers innervated by it |
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Term
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Definition
| point where a nerve fiber meets its target cell |
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Term
| neuromuscular junction (NMJ) |
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Definition
| when target cell is a muscle fiber |
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Term
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Definition
-swollen end of nerve fiber
–contains synaptic vesicles filled with acetylcholine (ACh) |
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Term
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Definition
| tiny gap between synaptic knob and muscle sarcolemma |
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Term
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Definition
-thin layer of collagen and glycoprotein separates Schwann cell and entire muscle cell from surrounding tissues
–contains acetylcholinesterase (AChE) that breaks down ACh after contraction causing relaxation |
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Term
| acetylcholinesterase (AChE) |
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Definition
| breaks down ACh after contraction causing relaxation |
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Term
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Definition
| a form of spastic paralysis caused by toxin of Clostridium tetani |
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Term
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Definition
| a state in which the muscles are limp and cannot contract |
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Term
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Definition
| compete with ACh for receptor sites, but do not stimulate the muscles |
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Term
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Definition
| type of food poisoning caused by a neuromuscular toxin secreted by the bacterium Clostridium botulinum |
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Term
| Electrically Excitable Cells |
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Definition
| •stimulated (active) muscle fiber or nerve cell |
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Term
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Definition
| hardening of muscles and stiffening of body beginning 3 to 4 hours after death |
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Term
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Definition
| central nervous system continually monitors and adjusts the length of the resting muscle, and maintains a state of partial contraction |
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Term
| isometric muscle contraction |
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Definition
| muscle is producing internal tension while an external resistance causes it to stay the same length or become longer |
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Term
| isotonic muscle contraction |
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Definition
| muscle changes in length with no change in tension |
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Term
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Definition
•all muscle contraction depends on ATP
•ATP supply depends on availability of:
–oxygen
–organic energy sources such as glucose and fatty acids
•two main pathways of ATP synthesis
–anaerobic fermentation
–aerobic respiration |
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Term
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Definition
•enables cells to produce ATP in the absence of oxygen
•yields little ATP and toxic lactic acid, a major factor in muscle fatigue
•much less efficient |
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Term
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Definition
•produces far more ATP, 36 ATP per glucose
–efficient means of meeting the ATP demands of prolonged exercise
•less toxic end products (CO2 and water)
•requires a continual supply of oxygen |
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Term
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Definition
| progressive weakness and loss of contractility from prolonged use of the muscles |
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Term
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Definition
–ATP synthesis declines as glycogen is consumed
–motor nerve fibers use up their ACh |
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Term
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Definition
| the ability to maintain high-intensity exercise for more than 4 to 5 minutes |
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Term
| Strength and Conditioning |
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Definition
•muscles can generate more tension than the bones and tendons can withstand
•resistance training
•endurance training |
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Term
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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
-limited to the heart where it functions to pump blood
–uses aerobic respiration almost exclusively
•rich in myoglobin and glycogen |
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Term
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Definition
| waves of contraction brought about by food distending the esophagus or feces distending the colon |
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Term
| stress-relaxation response (receptive relaxation) |
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Definition
| helps hollow organs gradually fill (urinary bladder) |
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Term
| Contraction and Stretching |
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Definition
•skeletal muscle cannot contract forcefully if overstretched
•smooth muscle contracts forcefully even when greatly stretched
–allows hollow organs such as the stomach and bladder to fill and then expel their contents efficiently
•smooth muscle can be anywhere from half to twice its resting length and still contract powerfully |
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Term
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Definition
| group of hereditary diseases in which skeletal muscles degenerate and weaken, and are replaced with fat and fibrous scar tissue |
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Term
| Duchenne muscular dystrophy |
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Definition
-caused by a sex-linked recessive trait (1 of 3500 live-born boys)
–most common form |
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Term
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Definition
| autoimmune disease in which antibodies attack neuromuscular junctions and bind ACh receptors together in clusters |
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