Exam 7 Physiology Study Guide Our muscles need a ton of ATP for both movement and relaxation Muscle Making ATP 2 big categories of making ATP substrate oxidative phosphorylation Substrate level 3 Glycolysis Kreb s and creatine phosphate 1 Creatine phosphate via substrate level phosphorylation 1 creatine phosphate 1 ATP Move phosphate attached to creatine to ADP to create equation 1 in opposite direction Initial source of ATP only takes 1 step to make vs glycolysis 10 steps Used to start moving muscle but quickly gone Limited supply we can only have so much creatine phosphate in our muscles Ex Body builders who try to pack in creatine phosphate to get more quick muscle movement changes osmolarity in our muscles water rushes in Get swelling in muscles from water Too much creatine can become toxic Supply is replenished during relaxation creatine creatine phosphate 2 Glycolysis Break down of sugars from blood or glycogen stores sugar Athletes carb load before endurance race increases glycogen storage 1 sugar 2 ATP Used alone during intense prolonged activity typically anaerobic Used with other processes during aerobic activity too Can be anaerobic no oxygen produce lactic acid Components replenished during relaxation remove lactic acid from muscles 3 Oxidative Phosphorylation Electron Transport Chain 1 process 32 34 ATP Continued supply during moderate exercise can t overuse oxygen supply ONLY aerobic 4 Kreb s Cycle ONLY aerobic relies on recycling products from oxidative phosphorylation 1 process 2 ATP Amino acids fatty acids start in the Kreb s cycle Whole Muscles Contraction produced by cross bridge cycling by many sarcomeres contraction shortening Bigger the contraction more sarcomeres involved Generates a mechanical force Tension from myosin heads pulling on actin fibers Allows us to move a load from point A to B like tug of war Opposed by the load that we are moving Ex If bicep being used load includes weight of forearm vs exercise phys Holding a 10 kg weight load is more than 10 kg Muscle shortening depends on tension load necessary for body movement Can work muscles without joints changing position size contraction shortening Contractions Isometric same length no change in length of muscle Pushing pulling on loads that are way too big contractions still occurring Ex Bronson tries to lift podium which is bolted to floor Tension load NO shortening Isotonic No change in tension muscle maintains specific level of tension Done most often muscle does shorten tension just above load Tension load shortening More tension more cross bridge cycling more ATP spent Not going to spend more than necessary Eccentric Muscle lengthens Muscle must deal with the load present unlike isometric b c its being supported across the muscle Isometric load is supported by something other than muscle Load tension Isotonic contraction degree of contraction related to load Initial period of isometric contraction tension load Isometric contraction must happen first increasing tension Ex initial grunting of large weightlifters before can start moving weight to build enough tension longer grunting time needed to lift heavier loads Shortening begins after tensions exceeds load Relationships btw load and isotonic contraction Increase of load Increase latency longer isometric contraction Decrease velocity how fast process occurs Decrease response can only fully contract bicep w light weight Impact of Repeated Stimulus APs Tension is summed only if muscle is hit w a 2nd stimulus before it reaches zero Tension builds like multiple depolarizations hitting postsynaptic cell Maintained contraction tetanus just a size not disease Unfused Partial relaxation between stimuli lose some tension Fused no time between stimuli to return calcium maximum contraction ATPase activity can t keep up with calcium present to put some away Want to do this when want higher tension levels in muscles Differences Between Myofibers 1 Speed of contraction of cross bridge cycle runners fast twitch vs slow twitch a Fast vs slow depends on enzymes used to breakdown ATP speed differs b Differ with respect to amount of ATPase activity c Hydrolyzing ATP on cross bridge Fast contractions deplete ATP more quickly but create more tension Slow contraction lasts longer but not as fast Ex Prius vs race car 2 Mechanism for Making ATP aerobic vs anaerobic Oxidative Maintain oxygen supply aerobic Vascularized Many blood vessels around myofiber to keep it oxidated Ex varicose veins new vessels created not a fixed system Oxygen Small nonpolar can cross plasma membrane want to keep in cell Must trick the gradient by packing outside or binding oxygen to big amphipathic protein that cant cross PM myoglobin Stores O2 in cells Athletes may target myoglobin levels to increase endurance Glycolytic Anaerobic No oxygen Few mitochondria why take energy to build them if not used 1 glucose 2 ATP 20 micrometers of movement Must have a boatload of glucose strung together by glycogen to help decrease osmolarity otherwise cell would swell hypertonic Ex Carb loading sets up body glucose available for aerobic and also when become anaerobic 3 Types of Fibers Dark light medium from combination of 2 categories above 1 Slow enzyme oxidative low ATPase activity use high ability to make ATP Tension remains constant over time but not high level Ex Like a 6 figure maker living at poverty level Very sustainable making tons of ATP and using little Not generating as much tension overall Like a Prius not fast but lasts a long time endurance 2 Fast enzyme oxidative glycolytic occurs first high ATPase activity Higher tension levels that decrease over time inputs remain the same but outputs usage increasing due to faster cross bridge cycling occurring fatigue 3 Fast enzyme Glycolytic high ATPase high glycolytic Most tension created but drops rapidly Not at all sustainable tension crashes quickly Using way faster than making ATP fatigue quickly Ex Fast loud muscle cars Muscles are combinations of all 3 types of fibers Proportion of each sets up what muscle is doing Increase oxidative red reddish coloration from myoglobin Increase glycolytic white myoglobin absent Ex Birds Red on thighs legs sustainable movement all the time don t fatigue easily White on flight muscles wings short burst of energy needed to escape predators short period of high tension Ducks breasts instead are darker meat b c they fly more on regular basis Genetic basis sprinters vs long distance runners Proportions can be
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