| Word | Definition |
| 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) |
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