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Exam 7 Physiology Study Guide*Our muscles need a ton of ATP for both movement and relaxationMuscle 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 ≠shorteningContractions:-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 musclesDifferences 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 activityc. 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 above1. 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  fatigue3. 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


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OSU EEOB 2520 - Exam 7

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