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Chpt 12 Muscle
| Question | Answer |
|---|---|
| M lines | structural proteins that anchor myosin during contraction |
| Titin | elastic protein attaching myosin to Z disc that contributes to elastic recoil of muscle |
| A band | dark,contains thick filaments (mostly myosin) |
| H band | light,center of A band, no overlap of actin and myosin |
| I band | light contains think filaments (mostly actin) |
| Z line/disc | |
| Sarcomere contraction | actin myosin filament side by side, actin is pulled toward the center H zones disappear and I band becomes very narrow |
| Cross bridges | sliding filament theory, myosin head contains an ATP-binding site which functions as an ATPase, converts ATP into ADP + Pi (Relax, Attachment ATP, rachets & slides actin, ADP + Pi) |
| Power stroke | conformational change which exerts force on actin |
| Tropomyosin | filament in grove between double row of G-actins |
| Troponin | complex is attached to tropomyosin at intervals of every 7 actins [I-inhibitor of myosin,M-tropomyosin association,C-calcium binding >10^-6M] |
| Sarcoplasmic reticulum | calcium reservoir in muscle |
| Terminal cisternae | where most of the calcium is in the sarcoplasmic reticulum |
| T tubules | run along terminal cisternae |
| Ideal resting length | is that which can generate maximum force; strength of muscle contraction influenced by: frequency of stimulation, thickness of each muscle fiber, initial length of muscle fiber |
| Optimal overlap | too close or too far apart, less tension bc fewer cross bridges can form |
| Twitch | single rapid contraction and relaxation of muscle fibers |
| Summation | 2nd stimulus occurs before muscle relaxes from 1st, the 2nd twitch will be greater |
| Complete tetanus, tetany | freq so fast no relaxation occurs, a smooth sustained contraction |
| Isotonic contraction | force remains constant throughout shortening process |
| Isometric contraction | exerted force does not cause load to move and length of fibers remain constant |
| Eccentric contraction | load is greater than exerted force and fibers lengthen |
| Maximum oxygen uptake(aerobic capacity) | max rate of oxygen consumption V02 Max |
| Lactate (anaerobic) threshold is % of max O2 uptake at which there is significant rise in blood lactate levels ~ 50-70& V02 max | |
| Intensity of exercise | mild plasma, free fatty acids; moderate exercise, muscle glycogen-plasma free fatty acids; heavy exercise, muscle glycogen |
| Oxygen Debt | accumulates during exercise withdrawn from hemoglobin and myoglobin, bc O2 is required for metabolism of lactic acid produced by anaerobic respiration |
| Phosphocreatine (creatine phosphate) | source of high energy Ps to regenerate ATP from ADP; 3X ATP levels |
| Slow-twich | Type I fibers slow fatigue, slow oxidative |
| Fast-twich | Type IIA(fast oxidative,aerobic) and IIX (fast glycolytic,anaerobic) fibers, fast fatigue |
| Satellite cells | fuse with existing cells |
| Central fatigue | occurs as brain is less able to |
| Upper motor system | plan and rehearse,remember practiced,coordinate complex (Primary motor cortex, akin to sensory motor cortex) |
| Lower motor neurons,final common pathway | motor neuron cell bodies are in ventral horn of spinal cord; axons leave in ventral root |
| Upper motor neurons | facilitory and inhibitory activity influenced by sensory feed back from muscles and tendons |
| Cerebellum | receives sensory input from spindles, Golgi tendon organs, and areas of corex devoted to vision, hearing and equilbrium [No descending tracts, influence motor activity indirectly, all output inhibitory, aids motor coordination] |
| Basal ganglia | |
| Relationship | UMN LMW MUSCLE |
| Motor unit | includes each motor neuron and all fibers it innervates |
| Innervation ratio | #of motor neurons:muscle fibers [1:100 fine control,less fibers to 1:200]{when a motor neuron is activated, all muscle fibers in its motor units contract |
| Recruitment | how do skeletal muscles perform smooth movements? |
| Neuromuscular junction | specialized region on myocyte |
| Action Potential | terminal buton Ach Nicotinic receptors Na+ ions move depolarize from motor end-plate out to the sarcolema; V-G ch AP myocyte-tubules[Excitation-contraction coupling] |
| Tension | information from golgi tendon organs |
| Length | muscle spindle apparatus |
| Intrafusal fibers | modified thin muscle cells; tell brain muscle bed is changing size; Nuclear bag fibers-loose aggregate:primary annulospiral sensory endings; Nuclear chain fibers-have nuclei in rows:secondary, flower-spray endings |
| Extrafusal fibers | regular muscle fibers |
| Coactivation | two class of neurons, alphas(muscle contraction and shortening-length); gammas(cause intrafusal to take up slack) |
| Knee-jerk reflex | tap,intrafusal fibers, base of spinal cord, alpha motorneuron, stimulates extrafusal muscle fiber to contract |
| Golgi tendon organ reflex | disynaptic reflex;3tension on tendons activates sensory neuron & 4tension on tendon is reduced |
| Reciprocal innervation | 1muscle stretch activates spindle apparatus 2agonist muscle contracts in stretch reflex 3antagonist muscle relaxes |
| Crossed-Extensor Reflex | get-back phenomenon heat glass nail involves double reciprocal innervation;affects contralateral side of cord |
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100001194417609
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