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Muscles 1
| Term | Definition |
|---|---|
| Movement | One of the functions of the muscles; allows the body to move to walk, talk, write, etc. |
| Stability | One of the functions of the muscles; maintains the posture of the body by preventing unwanted movements and maintaining tension |
| Sphincters | Internal muscular rings that control the movement of food, blood, and other materials in the body |
| Heat Production | One of the functions of the muscles; skeletal muscles generate waste heat that keeps one warm (e.x.: shivering) |
| Glycemic Control | One of the functions of the muscles; they absorb and store glucose, helping to regulate blood sugar concentration within normal range |
| Endomysium | Connective tissue around muscle cells |
| Perimysium | Thick connective tissue sheath that wraps muscle fibers into muscle fascicles |
| Muscle fascicles | Bundles of muscle fibers wrapped by perimysium |
| Epimysium | Connective tissue surrounding entire muscle |
| Fascia | Sheet of connective tissue that separates neighboring muscles from each other |
| Fusiform | Muscle that's thick in the middle and tapered at the end |
| Parallel | Muscle of uniform width and with parallel fasciciles |
| Triangular | Muscle that is broad at one end, narrow at the other |
| Unipennate | Muscle that is feather shaped; fascicles approach tendon from one side |
| Bipennate | Muscle that is feather shaped; fascicles approach tendon from both sides |
| Multipennate | Muscle that is feather shaped; bunches of feather shaped muscles converge to single point |
| Circular | Muscle that looks like a ring around a body opening |
| Responsiveness | A characteristic of all muscles; stimuli will lead to response with electrical charges across plasma membrane |
| Conductivity | A characteristic of all muscles; local electrical charge triggers a wave of excitation that travels along fiber and leads to contraction |
| Contractility | A characteristic of all muscles; shortens when stimulated, allowing for movement |
| Extensibility | A characteristic of all muscles; stretches between contractions |
| Elasticity | A characteristic of all muscles; can return to original resting length after being stretched |
| Skeletal Muscle | Voluntary, striated muscle attached to one or more bones |
| Striations | Alternating light and dark transverse bands, as the result of contractile proteins overlapping with each other |
| Myofiber | Muscle fiber, myocyte, muscle cell |
| Sarcolemma | The plasma membrane of a muscle fiber |
| Sarcoplasm | The cytoplasm of a muscle fiber |
| Myofibrils | Long protein bundles that occupy the main portion of the sarcoplasm |
| Glycogen | Energy storage; stored in abundance to provide energy with heightened exercise |
| Myoglobin | Red pigment that stores oxygen needed for muscles activity |
| Sarcoplasmic Reticulum | SR, smooth ER in muscle fiber that acts as a calcium reservoir |
| Multinucleated | Being composed of multiple nuclei |
| Myoblasts | Stem cells that fuse to form each muscle fiber |
| Satellite cells | Unspecialized myoblasts remaining between muscle fiber and endomysium; can restore small damage to muscles |
| Terminal cisternae | Dilated end-sacs of SR which cross the muscle fiber from one side to the other |
| Transverse (T) tubules | Tubular infoldings of the sarcolemma which penetrate through cell and emerge on the other side |
| Triad | One T tubule, two terminal cisterns |
| Thick filaments | Filament of muscles made of several hundred, golf club-shaped myosin strands |
| Myosin | Contractile protein that interacts with actin, found in thick filaments |
| Thin filaments | Filament of muscles that have intertwined strands of protein, made of Fibrous Actin and Tropomyosin |
| Fibrous actin | Contractile protein; intertwined strands of globular actin of thin filament with active sites that interact with myosin |
| Tropomyosin | Regulatory protein on thin filament that blocks active sites of actin, preventing contraction |
| Troponin | Small, calcium-binding regulatory protein on each tropomyosin molecule |
| Elastic filaments | Titin-containing filaments that flank the thick filaments and anchors them to the Z disc at the end M line at the other; stabilization |
| Titin (connectin) | Huge springy protein that stabilizes thick filaments |
| Bare zone | Location on thick filament where there are no myosin heads |
| Dystrophin | Accessory proteins that links actin in outermost myofilaments to transmembrane proteins and eventually to endomysium; can cause muscular dystrophy if defective |
| Duchenne Muscular Dystrophy | Most common form of muscular dystrophy; sex-linked recessive trait in 1:3500 live-born boys |
| Myasthenia Gravis | Autoimmune disease where antibodies attack neuromuscular junction and bond the ACh receptor, stopping contraction; mostly in women ages 20-40 |
| A Band | "Anisotropic"--Dark band where thin and thick filaments can overlap |
| H Band | Middle of A band; thick filaments only |
| M Line | Middle of H band |
| I band | "Isotropic"--alternating lighter band composed of elastic and thin filaments |
| Z disc | Anchors thin and elastic filaments |
| Sarcomere | From one z disc to another z disc |
| Denervation Atrophy | Shrinkage of a paralyzed muscle when a nerve connection to the muscle is severed and not restored |
| Somatic Motor Neurons | Nerve cells that serve skeletal muscles |
| Somatic motor fibers | Axons lead to skeletal muscle |
| Motor unit | One nerve fiber and all of the muscle fibers innervated by it |
| Small Motor Units | Contain few muscle fibers per neuron to allow for fine degree of control |
| Large Motor Units | Contains lots of muscle fibers per neuron that allows for power |
| Synapse | Point where a nerve fiber meets its target cell |
| Neuromuscular Junction | A synapse where the target cell is a muscle fiber |
| Synaptic knob | Swollen end of nerve fiber, containing synaptic vesicles filled with acetylcholine |
| Synaptic Cleft | Tiny gap between the synaptic knob and muscle sarcolemma |
| Schwann cell | Satellite cell of neuron that envelopes and isolates all of the NMJ from the surrounding tissue fluid |
| Basal Lamina | Thin layer of collagen and glycoprotein separates Schwann cell and entire muscle cell from surrounding tissues |
| Acetylcholinesterase (AChE) | Breaks down ACh, causing relaxation |
| Acetylcholine (ACh) | Transmitted by the neuron, causes muscles to contract |
| Resting membrane potential | -90 mV, maintained by sodium-potassium pump |
| Potential in unstimulated cell | Excess sodium in ECF, excess potassium in ICF, anions inside of membrane that make the inside more negative compared to the outside |
| Potential in stimulated cell | Sodium gates open, bringing Na into the cell and depolarizes it. Na gates close and K gates open, K rushes out of cell. Repolarizes cell. |
| Action potential | Quick up and down voltage shift from negative RMP to positive value, and back to negative value again |
| RMP | Stable voltage seen in waiting muscle or nerve cell |
| Depolarization | The plasma membrane becomes positive due to Na and K cations present in the cell |
| Repolarization | The plasma membrane becomes negative as K ions leave the cell after depolarization |
| Cholinesterase inhibitors | Toxin that binds to AChE and prevents it from degrading ACh, causing spastic paralysis |
| Spastic paralysis | Continual contraction of the muscles with no relaxation, can lead to suffocation |
| Tetanus | Lockjaw; spastic paralysis caused by C. tetani that blocks glycine release and leads to overstimulation of the muscles |
| Glycine | Found in spinal cord, stops motor neurons from producing unwanted muscle contractions |
| Flaccid paralysis | A state in which the muscles are limp and cannot contract |
| Curare | Compound that competes with ACh for receptor sites, but do not stimulate the muscles |
| Botulism | Botox; neuromuscular toxin secreted by C. botulinum blocks release of ACh, causing flaccid paralysis |
Created by:
Rylyn27463
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