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Muscle Lab
Physiology 2010
Question | Answer |
---|---|
Motor unit | a motor neuron plus all the muscle fibers it innervates |
Cell body | aka soma, receiver, located in the brain and spinal cord |
Dendrites | extension from cell body, receiver |
Axon hillock | area on axon where signal priority is highest |
Axon | extension from cell body where action potential is conducted |
Schwann cells | myelin sheath in PNS, keeps AP from leaking out and increases speed of AP |
Nodes of Ranvier | spaces between myelin sheaths |
Salivatory conduction | AP jumps from node to node (400x faster) |
Resting membrane potential | (-70mV) cell is more negative inside than outside |
Threshold | (-55mV) need to reach the threshold in order to fire an AP |
Depolarization | (-70mV to +40mV) voltage gated Na+ channels opens and Na+ flows in |
Repolarization | (+40mV to -70mV) voltage gated Na+ channels close, voltage gated K+ channels slowly open amd K+ flows out |
Hyperpolarization | (+40mV to -90mV) voltage gated K+ channels slowly close but K+ still leaks out |
Which voltage gated channels open and close fastest? | Na+ is faster than K+ |
Absolute refractory period | channels lock so AP doesn't travel backwards |
Properties of muscle tissue | excitability, contractibility, extensibility, and elasticity |
Excitability | ability to receive and respond to stimulus |
Contractability | ability to shorten forcbly when adequately stimulated |
Extensibility | ability to be stretched or extended |
Elasticity | ability of muscle fibers to resume to its resting length |
3 types of muscles | skeletal, smooth, and cardiac |
Skeletal muscle | striated, voluntary and multinucleated |
Smooth muscle | smooth, involuntary and uninucleated |
Cardiac muscle | striated, involuntary and uninucleated |
Epimysium | dense irregular CT that suurounds the entire muscle |
Perimysium | CT that surrounds each fascicle |
Endomysium | CT that surrounds each muscle fiber |
4 functions of skeletal muscle | produce voluntary movement, maintain posture, stabilize joints, and generate heat |
Transverse Tubules (T-tubes) | in between sacroplasmic reticulum |
Sacroplasmic Reticulum | stores Ca+ and is made of myofilaments actin and myosin |
Myosin | thick filament |
Actin | thin filament, has binding sites for myosin but is blocked by tropomyosin |
Tropomyosin | covers myosin binding sites |
Troponin | binds with Ca+ to remove tropomyosin so myosin can attach to actin |
Cross bridges | are created when myosin attaches to actin, need ATP to detach |
Power stroke | the myosin heads pull actin and actin promotes ATP --> ADP + Pi |
ATP Hydrolysis | cocks myosin heads to start another cycle |
A band | contains myosin and actin |
I band | contains actin and z discs |
Latency period | time from stimulation to beginning of contraction |
Contraction period | length of time to get a maximum response |
Relaxation period | dissociation of myosin from actin, myofilaments sliding back in to original positions and Ca+ is pumped back into the SR |
Temporal (time) summation | increase frequency, increases magnitude |
Tetanus | long sustained contraction |
Spatial summation (recruitment) | increase voltage, strengths current to increase magnitude, and recruits more motor units |
Isometric contraction | length of muscle does not change (example: holding a bag) |
Concentric isotonic contraction | muscle is getting shorter (example: lifting a book) |
Eccentric isotonic contraction | muscle is getting longer (example: lowering a book) |