Exam 1 Study Guide: APK3110c: Applied Exercise Physiology
Exam 1 Study Guide: APK3110c: Applied Exercise Physiology APK3110c
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This 15 page Study Guide was uploaded by Courtney Adams on Sunday September 20, 2015. The Study Guide belongs to APK3110c at Florida State University taught by Dr. Robert Moffatt in Fall 2015. Since its upload, it has received 353 views.
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What is ATP Applied Exercise Physiology Review Guide Exam I September 22 2015 How does it function How is ATP formed What is the role of PCr in the formation of ATP 0 ATP Adenosine Pi Pi Pi triphosphate the main energy currency of the body the only energy currency for muscles to do work 0 Think of ATP as money that can be used to power your muscles 0 Function splitting phosphate bonds to produce large amounts of energy 0 O O The energy stored in these bonds can be drawn upon to do work ATPase ATP ADP Pi Energy allows work lt gt Here we took the chemical energy in ATP released it converted it into mechanical energy WORK some heat energy is released as a result of this ATP is an adenosine molecule one of the bases of DNA attached to three phosphates When one phosphate is cleaved energy is released during the cleavage One thing you will notice is everything in the body is controlled via adding a phosphate to something or taking a phosphate off Formed glycolysis D citric acid cycle D ETC phosphocreatine CK D ATP and creatine breakdown of carbsproteinsfats ADK 2AP D 1ATP 1AMP O 0 ATP is produced in the mitochondria powerhouse of the cell D where we can produce vast amounts energy but requires oxygen to do that doesn t need oxygen to be degraded or hydrolyzed ATP is locatedstored in the cytoplasm of the cell close proximity to the myo laments contractile proteins that allows the muscle to contract some small amount is produced in the krebs cycle occurs in the mitochondria anaerobic provides energy quickly but doesn t sustain it for long close proximity needs oxygen to replenish it 0 Role of PCr 0 Don t have that much ATP only lasts for 23 secs so other energy storage forms donate energy since ATP doesn t last very longlj Creatine Pi creatine phosphate When we hydrolyze ATP we create energy phosphorous ow and we create ADP The cells monitor the ratio of ATP to ADP CK is regulated by the ADPATP ratio Cr Pi Energy CK Creatine PK gt 0 When the ADP levels get high or ATPADP ratio gets out of whack the system knows very quickly there is a demand for energy so creatine kinase enzyme is activated breaking the bonds between Cr and Pi creating more energy allows us to perform another several seconds of work D this energy is then involved in muscle contraction 2 Differentiate between aerobic and anaerobic metabolism Aerobic Metabolism quotwith oxygenquot or quotslow glycolysisquot since it takes a long time to utilized but provides much more energy 0 O O O O Occurs in the mitochondria Sole purpose is to produce energy large amounts using 02 Starts 34 min into activity End product is pyruvate in anaerobic metabolism it goes an extra step to lactate Pyruvate is in the cytoplasm of the cell During rest mainly using aerobic metabolism Substrate fat Lactate Production minimal 10mg100mL of blood 02 consumption 250 mLmin can vary by size of person Acetyl CoA An interesting thing about Aerobic glycolysis is that pyruvate doesn t produce lactic acid Pyruvate will go into the mitochondrial membrane A couple events occur 1 Remove a carbon consume oxygen to give off carbon dioxide photosynthetic process and that s where the carbon goes 2 Acetate with coenzyme A to produce Acetyl CoA so the 3C pyruvate is converted to a 2C acetate which couples with coenzyme A to form Acetyl CoA Anaerobic Metabolism quotwithout oxygenquot or quotfast glycolysisquot since it supplies energy fast and is used when we need energy right away 0 O O O O Occurs in the cytoplasm 1mol 6C molecule D 2mol 3C molecules known as lactate D ATP Generates ATP End product Lactic acid NADH reduces pyruvate to create lactic acid AKA Lactic acid system because that is the nal byproduct Lactic acid can cause pain lower pH and also be used for energy production Lactic Acid changes the PH D cell usually functions under a ne range PH and if you disrupt that range D cell doesn t work as ef ciently Lactic Acid coupled with running out glucose fuel D you will start to walk NO longer at an intense pace Ends with 3 ATP from Anaerobic Glycolysis but if the blood transfers in the glucose it will cost 1 ATP making the end total now 2 ATP o Glucose stored in the muscle can be quickly broken down and used 0 Primary concern To take whatever substrate we have available that enables us to continue to perform work in a long term basis to release energy so we can take that energy from the derogation of this 1 mole of glucose to allow ADP and Pi to be coupled to form ATP ATP production starts with glycolysis in the cell s cytosol The sixcarbon molecule is cleaved over many steps into two threecarbon molecules called pyruvate This is known as anaerobic respiration since oxygen is nowhere in the equation At this point the pyruvate can form lactate to keep glycolysis running if ATP is needed fast during intense exercise or it can enter the cell s mitochondria Once it enters the mitochondria it is committed to aerobic respiration and it is known as such This process is very lengthy but produces much more energy than glycolysis alone Oxygen is the nal electron receptor for this Describe glycolysis Glycolysis breaking down glucose to make more ATP don t need oxygen to do that o Occurs in the cytoplasm of the cell 0 Start with glucose go through a bunch of reactions end with pyruvate Anaerobically intense exercise glucose becomes lactate Aerobically glucose becomes acetyl coA 0 Rate limiting enzyme PFK Inducible enzyme to increase or reduce reactivity of the enzyme Gatekeeper enzyme if you don t instigate its actions or don t have enough of the ingredients it could inhibit the glycolytic process Key enzyme in the whole process Levels of ADP PH etc act on the enzyme to turn reaction on oro o 1 mol 6C degraded until we have 2 3C molecules 0 In the two reactions NADNADH is a transporter in the ETC used in oxidation acceptorsreduction donors reactions this is what happens when we have pro ciencies of oxygen when oxygen is abundant different events occur 0 Almost all steps are reversible 0 We can also get glucose from the blood but only in AEROBIC conditions enters into glucose6phosphate NOT under ANAEROBIC conditions doesn t happen quickly don t normally depend on blood as a source of fuel so NOT immediate Anaerobic glycolysis ends with 3 ATP from but if the blood transfers in the glucose it will cost 1 ATP making the end total now 2 ATP Describe the Krebs Cycle and ETS Krebs Cvcle Acetic Acid CvclePCA Cvcle o Occurs when oxygen is available 0 If energy isn t required right away endurance exercise Instead of forming lactate pyruvate will enter the cell s mitochondria Once it enters the mitochondria known as the powerhouse of the cell it has committed to aerobic respiration Once inside it will form acetylcoA along with a NADH this is irreversible As acetylcoA it will go through many reactions which release C02 this is what we exhale and they will also form NADH and FADH2 along with a GTP In the Krebs cycle we will take the 6C compound citric acidD high energy state recon gure it pull some electrons off cut off carbons until we end up with OAA or a 4C compound Beginning of Krebs take Acetyl CoA and couple it with citric acid Alphaketoglutarate is no longer a 6C molecule its now a 5C molecule which means that we have removed 1C and that C is let off as C02 NAD then comes in and takes off another electron and AKG is oxidized to Succinate Acid 4C compound once again we removed a C last C we will remove When you break off the last C we get a release of energy in the form of 1 GTP that is the same as 1 ATP energy that we can use to contract muscles Bvitamins involves in creating energylj FAD Ribo avin NAD Niocin For every 6C compound G6P we get 2 ATP from the Krebs cycle compared to glycolysis starting with glycogen gets us 3 ATP All ATP molecules are produced by substrate level phosphorylation TOTAL 4 NADH 1 FADH2 and 1 GTP but remember that we have two pyruvates so we double everything to give 6 C02 8 NADH 2 FADH and 2 GTP 3638 ATP depending on the starting point 0 Electron Transport ChainSystem Respiratory Chain how we produce energy in the mitochondria each electronsH s is transported to the ETC 0 O O 0 Need oxygen for this to effectively work NADH and FADH are thought of as quotenergy vouchersquot they don t have any energy until they reach the ETC They produce the bulk of ATP that cellular respiration yields There are four complexes that make up the chain and each complex takes away electrons from the NADH and FADH The very last complex takes all the electrons and uses them to form an ATP molecule Oxygen is the nal electron acceptor and this is why we need to breathe oxygen to live Think of the complexes as a tower the NADH enters the top tower and then enters the second complex underneath it and so on till it reaches the last one and forms energy At each complex electrons are pumped out of the NADH At the last complex there is enough electrons to form 3 ATP So each NADH forms 3 ATP FADH2 enters the second complex so it skips the rst one This means that fewer electrons are pumped out of FADH2 so the last complex only forms 2 ATP So each FADH2 forms 2 ATP Eventually the electrons combine with hydrogen ions and oxygen reduction to produce water It is the nal stage or aerobic respiration 0 Ex Like a waterfall You can watch the beauty of the waterfall and it looks great but that s all it is But if you gure out a way to funnel water through a channel something like a tube and if something inside the tube rotates and churns the water you can generate powerelectricity So when the waterfalls over the waterfall and if you harness it properly you will generate energy This is essentially what is happening here You take the electrons and you take it to the top of the falls and it falls over and goes through speci c chemical channels that release energy to form ATP Krebs 30 ATP Aerobic Glycolysis 9 ATP 39 ATP FAD 2 ATP NAD 2 ATP 5 Compare and contrast the three energy systems ALWAYS go through the same sequenceljl ATPPC Anaerobic Glycolysis Aerobic Metabolism o The intensity and duration will determine the prevalence of that energy system to supplying energy for that effort 0 Always start out with ATP and work to provide energy to replace ATP 0 ATP can be formed by breaking down CP so it will release its energy to reform Pi ADP ATP which then can be hydrolyzed in the muscle so it can continue to contract D provides a shift towards anaerobic gycoysis If the event is a longer amount submaximal you will see a great dependence of aerobic metabolism 0 ATP CP 0 No reliance on oxygen Supplies energy for no more than 68 seconds To get its power it uses quothigh energyquot stored body chemicals Ex power and weight lifters Anaerobic Glycolysis quotwithout oxygenquot 0 When quotsteady statequot is breached by increasing our efforts and using more energy 0 Produces lactate o Supplies energy for up to 90 seconds Aerobic Metabolism quot with oxygenquot 0 Called quotsteady statequot because the body s energy demands are balanced by energy supply This allows us to continue to exercise hence the quotsteady statequot 0 Provides a base of tness 0 Ex distance running 0 Fat is a fuel source Aerobic training increases the body s ability to mobilize fat as an energy source at submaximal intensities as well as improving carbohydrate metabolism 0 As the exercise extends in time your begin to provide more and more energy 0 We use some combination of fats and carbs to get from point A to point B to support Aerobic energy production Ranking Energy Systems by Exercise 0 By Rate 1 ATPPC fastest allows it to occur almost instantaneously 3 moles 2 Lactic Acid System Anaerobic Glycolysis 16 moles 3 Aerobic Metabolism By capacity of ATP produced 1 Aerobic Metabolism 100 moles of ATP capacitywise 2 Anaerobic Glycolysis 12 moles 4 ATPPC system 07 moles 6 Describe oxygen de cit and oxygen debt during light and heavy exercise 0 Oxygen De cit The difference between 02 consumed and 02 that would have been consumed had an individual had reached steady state immediately 0 It is critical to understand that prior to reaching steady state the body must produce energy anaerobically until steady state is reached 0 Our body uses a certain amount of oxygen while we are resting The once we start to exercise a gap between the amount of oxygen that our body needs to be in quotsteadystate and the amount that we currently have since we were resting is created our body has to ll this gap So we have to get this oxygen from increasing our core body temperature increasing our metabolism ventilating faster etc This gap is called the oxygen de ciency we are de cient in the amount of oxygen that our body needs to exercise 0 There is a difference between what you need to do the work and what you can actually provide 0 We just cannot engage in the aerobic system fast enough to do this kind of work right away 0 NEVER will be able to provide all the energy aerobically 0 Will ALWAYS be in De cit the difference between oxygen you can consume and the amount you actually consume Start accumulating lactate when we are in de cit D depends on the intensity of the exercise so lactate amount varies o De cit Increase H ions D lncrease lactate D Decrease muscle glycogen D Decrease ATPPC Exercise 0 Oxygen Debt Amount of oxygen consumed during recovery excluding the amount of oxygen which would have been consumed at rest during that same time 0 So right after exercise our body has this oxygen debt to settle Physiologically our body is recycling lactate lowering its core temperature making enzymes replenishing glycogen etc This all results in an elevated metabolism post exercise and the period where your metabolism is elevated is called the EPOC excess post oxygen consumption 7 speci cally the alactaid and o Bc we have gone from point A to point B bc we equated lactate and depleted fuels D you have a debt to pay to replace it 0 Debt in the form of excess oxygen being consumed during recovery D EPOC E EPOC Excess Post Oxygen Consumption o 2 components in respect to oxygen debt 1 How long does it take to recover to get back to baseline 0 The time of recovery timeplace it takes to get back to the baseline 2 How much oxygen you consume during that time 0 Oxygen consumed during recovery excluding the amount of oxygen which would ve been consumed during rest during that same time Relationship between the de cit and the debt occurred because you weren t able to supply what you need immediately bc it took 24 minutes to do that 0 Debt will always be larger than the de cit o What you borrow from the bank will always be a larger amount than what you borrowed Durinq light vs heavv exercise 0 During light exercise the oxygen de ciency is smaller as expected less oxygen is needed since the intensity is lighter During heavy exercise the de ciency is much greater and is actually never closed completely Describe what occurs in the phases of oxygen debt lactaid portions There are two phases of oxygen debt Fast and Slow Recovery from strenuous exercise with higher lactate levels body temp and hormones levels increase substantially this is the slow phase which also induces the fast phase and can last up to 24 hours for complete recovery Train subjects have a faster recovery rate Lactate accumulation from anaerobic component represented the use of glycogen so the ensuing 02 debt served two purposes 0 Reestablishing the original glycogen stores by synthesizing approx 80 of lactate back to glycogen in the liver Cori Cyle o Catabolizing remaining lactate through pyruvateTCA cycle pathway ATP generated presumably powered by glycogen resynthesized from lactate Alactacid 02 debt rapid phase oxygen debt without lactate buildup fast replenishment 0 Amount of oxygen required to replenish stores of ATP and PC in muscle tissue It is replaced by Aerobic Metabolism which is why it happens so quickly 23 min 0 Restoration of ATP and CP using energy provided from breakdown of stored macronutrients carbs fats proteins 0 Small restoration of hemoglobin and myoglobin 8 9 and heavy exercise Rest Aerobic Glycolysis Beta oxidation using a mixture of all three fuels CHO protein plays a small amount and fat a mixture of 4060 fats vs carbs seems like there will be NO lactate produced but in reality there is some lactate being produced 10mg per 100 mL of blood always some leaking O Alactaid is just the portion of the oxygen debt that does not involve anything with lactate so this is mostly with light exercise Lactacid 02 debt slow phase oxygen debt associated with elevated lactate levels slow replenishment O O O O O Lactate removal in addition to other things requiring energy Amount of 02 required to remove lactate from the muscles With 02 available majority of lactate is converted to pyruvate and oxidized to C02 and H20 while also releasing the remainder of energy from lactate Some converts back to glycogenglucose small portion to protein Active recovery aids in lactate removal by maintaining greater supply of blood to muscle may take an hour This phase is responsible for converting lactic acid to glycogen in liver Cori cycle Updated theory of EPOC lactate removal in addition to other things requiring energy Lactaid portion is the recycling of the lactate to the liver This is mostly during high intensity and heavy exercise How is lactate formed during glycolysis What are the conditions under which it is formed Lactate is produced to keep glycolysis running but the breakdown of lactate produces H ions The buildup of these cause the blood around the muscles to become more acidic and once enough ions buildup our body has a buffer to clear them but once the intensity gets high enough the buffer can t keep up enough the high acidity leave 0 O 0000 NADH gives electrons to pyruvate to produce lactate Lactate will be produced when we are in de cit The more intense the effort the more lactate we will accumulate Inhibits the mobilization of fatty acids Occurs during Anaerobic Glycolysis in the absence of oxygen 5570 will be converted back to pyruvate to use as a fuel Occurs in the cytoplasm of the cell Lactate is the main contributor to exhaustion A decrease in muscle glycogen D lack of fuel D inhibits muscle contraction l FATIGUE An increase in H l inhibits muscle contraction l FATIGUE What is the primary fuel for rest light to moderate exercise REST FAT CHO Aerobic Metabolism HLA 10 mgdl small amount in the system so it does produce SOME lactate 0 Light to Moderate Exercise Long Duration exhausted in 60 minutes submaximal intensity rst anaerobic until it reaches 23 minutes in then turns into aerobic metabolism fat is used as a fuel quotsteady statequot suggest that the de cit may in fact disappear during that long submaximal effort Heavv Exercise Short Duration exhausted in 2 minutes maximum intensity sprinted as hard as you could ATPPC Anaerobic Glycolysis some aerobic contribution under this condition you will never ever just get aerobic metabolism supporting that 2 min worth of max intensity carbohydrates in the form of muscle glycogen will use the energy stored ATP very quickly you will use the energy stored in CP to make more ATP very quickly and you will depend on anaerobic glycolysis to provide energy that is released by the derogation of blood glucose from muscle glycogen also very quickly And as time goes on you will have a little more contribution from aerobic metabolism The once we start to reach hard and maximal exercise our body shifts to using carbohydrates for fuel Even though fat produces much more ATP than carbohydrates SHORTEDNIIJEIEENMAX carbohydrates are preferred Carbs are superior when oxygen is limited ATPPC 39d CH0 glycogen The longer the event the Anaerob1c some aerob1c more aerobic the event HLA 175mgd1 will be Absence of oxy 13 the mam 10 Describe active and passive recovery What effect do they have on lactate removal 0 Active Recovery 0 4060 of activity 0 Recovery after hard exercise where the muscles are moving so jogging at the end of a track workout or race 0 Active recovery stimulates lactate removal By contracting your muscles blood ow is increased and this increases lactate clearance o Lactate is recycled in the liver and reforms glycogen and by increasing blood ow more lactate will enter the liver and by recycled to produce energy for 4060 of active recovery This is called the Cori Cycle 0 Passive Recovery 0 ldle rest no movement 0 Simply just standing still after exercise Presuming that total inactivity reduces resting energy requirements freeing oxygen to fuel recovery process ex massage cold showers body positions consuming cold liquids 11 What is the fate of lactic acid 0 8090 goes to the Krebs cycle for energy production 0 Can also go to the Cori Cycle 0 Becomes pyruvate D glycogen goes back to the blood D liver makes new glucose 0 Lactate is converted to pyruvate which can then become glycogen in the blood where it is transported to the liver to make new glucose to begin the set of reactions again OR once converted to pyruvate can then be converted to acetyl coA to enter the Cori Cycle 0 Can interfere with PFK rate limiting enzyme slowing down glycolysis 0 CH0 in the diet are critical for replenishing glycogen stores 0 45 days to fully restore HLA D glycogen not dependent on diet o It is recycled in the liver and actually forms a lot of glycogen So lactate is actually pretty useful in the body 12 Draw a segment of the myo lament showing two sarcomeres A bands Z lines thin laments thick laments and H zones Explain the difference between the appearance of a relaxed versus contracted muscle l quotI Miss Hanna 2 ism I TTITTTTfquotZI TTZ39ITTTT39II39 r K 3911 f A quot7 quot quott 7quot r T w 7 a 39 3quotquot Thlrllaclln llamalit L 39 Thick m39lilnsinHilaIrnerll g Remus fracas L111 Ed HE MT l fig m Ti a l l CTI TquotquotquotVquot39Z39ZIIINST r TTCTT ZZCCTTETCeTZ ICCT Aband Mlma l I MVW l I I 39 77 mg A r F SErcunmere h 39I 311 Overview of the muscle 0 Myo laments actin and myosin D helps muscle actually develop tension Myosin red very large thick protein Actin blue thin protein less weight oActin is anchored to the zdiscs o Myosin and Actin are contractile protein Sarcomere the smallest functional unit of the myo ber Spreads from zdisc to zdisc oHelps determine what the muscle can actually do 13 o Actin is shared by conjoining sarcomeres Iband Lighter in appearance made of actin oLocated right down the center of the zdisc Aband Darker in appearance more content made of actin AND myosin oRight in the center of two zdiscs Hzone all you can see is the myosin oRight down the middle of the A band o The sarcomere is the smallest structural unit if the muscle ber Its boundaries are known as Zdiscs Striations are due to light disbursement on muscle myo laments dispersed by the proteins actin and myosin is contained in the sarcomere and actin is anchored to the Zline and overlaps the sarcomere In the middle is the Hzone The A band is darker than the Iband due to density and actin and myosin are present here on the Mline Appearance of relaxed vs contracted muscle 0 Upon contraction the A bands do not change in length whereas the Ibands and the Hzone shortens causing the Zlines to come closer together During rest the A band is visible as dark transverse lines across myo bers the Iband is visible as lightly staining transverse lines and the Zline is visible as dark lines separating sarcomeres at the lightmicroscope level During contraction the Zline discs move closer together with Actin and myosin being the protein laments responsible for contraction The Z disks on the sarcomere are literally pulled closer together they contract and thus the I band will decrease size in length since being pulled together The H zone will disappear as it is covered via the sliding action How does nerve stimulation lead to contraction What is the role of calcium in this process Skeletal Muscle Contraction In order for to contract a skeletal muscle must 0 O O 0 Must be nerve stimulation that innovates muscle activity comes through the muscle from a nerve ending An action Potential propagation of an electrical current will then run along the sarcolemma An increase in intercellular Calcium levels if contraction occurs FINAL trigger for contraction ExcitationContraction excite the nerve stimuli release Ca through that excitement l contraction of the muscle In order for contraction to occur there must be stimulation by a nerve ending It then propagates an electrical current or action potential along the sarcolemma The action potential results in a change of voltages and membrane permeability it moves to the axon terminal at the neuromuscularjunction where the synaptic vesicles contain ACH a neurotransmitter Via exocytosis ACH moves across the synaptic cleft binds to the ACHtransferase receptors and the NaK channels open Na is abundant on the outside and then changes inside outside ligand gated channels Propagating an action potential and countering fatigue depends on maintaining steep NaK gradients Decreased gradients severely affect muscle ber excitability and contractile performance 0 The muscle action potential depolarizes the ttubule causing Ca2 to be released from the terminal cisternae of the SR which in turn binds to Troponin on the actin causing a conformational change Once it binds to troponin tropomyosin is signaled to move from the gactin binding sites so the myosin head can bind Once attached the head pulls the laments together This is called excitationcontraction coupling The Z disks on the sarcomere are literally pulled closer together they contract and thus the I band will decrease size in length since being pulled together The H zone will disappear as it is covered via the sliding action Contraction will occur as long as the intramuscular concentration of calcium remains high as this is removing the typomyosin When the stimuli is over Ca2 is pumped back into the cisternae via CaATPase pump 14 Describe the difference between a muscle ber myo bril and myo lament Muscle Fiber cylindrical multinucleate cell composed of numerous myo brils that contracts when stimulated Myo bril any of the treadlike brils that make up the contractile part of a striated muscle ber 0 The sarcomere is another name for the myo bril and it is the smallest contractile unit of the ber and it repeats many times along the muscle and this gives origin to the striated patterns Myo lament any of the ultramicroscopic laments made up of actin and myosin which are structural units of a myo bril 0 Looking at an individual sarcomere you will see proteins called the myo laments These are the actin thin band and myosin thick band that you will hear so much about The sarcomere is separated into different segments depending on the presence of different myo laments The l band meaning isotropic contains just actin and the A band meaning anisotropic contains both actin and myosin Now in the middle of the A band is the H zone which is just myosin Then further dissecting the H zone is the M line which is just proteins to keep the actin and myosin in the correct spatial arrangement during contraction Then the Z disks separate each sarcomere since the ber is composed of hundreds to millions 15 What is the sarcoplasmic reticulum Explain how the SR is involved in contraction 16 contraction and relaxation 17 The sarcoplasmic reticulum SR is an extensive longitudinal laticelike network of tubular channels and vesicles It provides structural integrity to the cell It allows the wave of depolarization to spread rapidly from the bers outer surface to its inner environment through the ttubule system to initiate muscle action 0 The SR that surrounds each myo bril contains biologic pumps that take up Ca2 from the bers sarcoplasm producing a calcium concentration gradient between the SR higher and the sarcoplasm surrounding the laments lower Ca2 is released from the terminal cisternae of the SR Explain the role of troponin and tropomyosin in muscle Now to learn how the muscles actually contract So right now imagine two rows of sarcomeres just sitting at rest so there is no contracting going on and the muscle is not generating force The sliding lament theory is the theory of how a muscle contraction occurs Actin which is also called the thin lament is a globular protein The globes of actin wrap around each other to form a coil shape Each individual globe has a myosin binding site for the myosin head to attach to for the contraction but this is covered by a regulatory protein called trypomyosin So the trypomyosin wraps around the globe covering all of the myosin binding sites So how does myosin bind during contraction On every 7th globe there is another regulatory protein called troponin that is positioned on top of the trypomyosin When Ca2 is present and binds to troponin it will literally pull the trypomyosin out of the way exposing the binding sites for the myosin head Overview 0 Troponin sits apot Tropmyosin on the actin lament The attachment of Ca2 to Troponin allows Tropomyosin to move exposing the myosin binding sites Tropomyosin is the skinny protein that wraps around each actin lament Both Troponin and Tryomyosin are regulatory proteins Cause muscle contraction How is ATP involved in skeletal muscle contraction ATP binds to the myosin head forming ADP P When the Ca2 exposes the binding sites on the actin laments the myosin heads bind to the actin to form cross bridges ADP and P are released causing a change of shape of the myosin heads generating the sliding motion of actin toward the center of the sarcomere This pulls the zdiscs together effectively contracting the muscle ber to produce a power stroke ATP causes the cross bridge to unbind when a new ATP attaches to the myosin head the cross bridge between actinmyosin breaks recocking returning the myosin head to its unattached position Without adding new ATP the cross bridges would remain attached this is why corpses become stiff with rigor mortis 1 The quicker the myosin hydrolysis ATP the faster the cross bridge turnover leading to quicker shortening velocity 18 What is the role of ATPase in muscle contraction 0 ATPase breaks down ATP so energy is released and used to form actin myosin bridges It also breaks down ATP so energy is used in breaking the actinmyosin bridges o This is also the enzyme that determines if a muscle ber is slow or fast twitch o It is stimulated by calcium ions 19 What are the main ber types in skeletal muscle and how do they differ The three ber types are type 1 2a and 2X They are also called Slow twitch type 1 and fast twitch type 2a and 2x and this refers to the speed of contraction of the ber 0 When looked at in vitro the muscle was stimulated isometrically and this enabled the time to peak tension to be recorded Fast twitch bers took 1215 mmsec to reach peak tension and slow twitch took 5070 mmsec Tvoe 1 bers RED 0 Considered the slow twitch bers 0 Rely on oxidative enzymes to supply energy 0 They are rich in mitochondria l thus take a while to fatigue 0 They are rich in capillaries and myoglobin which make sense to supply them with all the oxygen they need for oxidative metabolism Many mitochondria and many blood capillaries 0 Have a slow contraction velocity very resistant to fatigue 0 Have high capacity to generate ATP by oxidative metabolism processes 0 These muscles are small compared to its fast twitch counterparts O 0 Type 2a 0 An intermediate of type 1 and type 2X o It is a fast twitch ber 0 Some oxidative properties so it has a high amount of mitochondria 0 Contains large amounts of glycogen 0 Unlike type 1 it is larger less blood capillary density and less myoglobin o This ber is also called the fast oxidative ber TVDe 2X WHITE 0 Opposite of type 1 o It is very fast contraction velocity and very fatigable Generates ATP anaerobically not able to supply muscle bers continuously wit suf cient ATP Relies mainly on glycogen and CP those immediate energy sources lts muscles are large have low capillaries myoglobin and mitochondria This is also called the fast glycolytic ber Because of its glycolytic reliance it has a highly developed sarcoplasmic reticulum Found in large numbers in muscles in the arm 20 What is the relationship between ber type distribution and performance Based on someone s muscle ber percentage we can predict what sport 21 they compete in 0 Slow twitch muscle bers A long distance runner These bers favor long endurance events Fast twitch bers It is reversed in sprinters 5050 ratio of fast to slow twitch Weightlifters and sedentary individuals What is a motor unit and what is its responsibility in muscle contraction It is made up of a motor neuron and skeletal muscle bers that are innervated by that axon Groups of motor units often work together to coordinate the contraction of a single muscle All of the motor units in a muscle are considered a motor pool Basically its responsibility is to innervate the muscle bers by way of an action potential Source Lectures lab and textbook chapters 57 18 and 21 pp 46467
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