Transcript Slide 1
MUSCLE METABOLISM Where is ATP needed? binding site thin filament (actin) myosin head ADP 12 thick filament (myosin) ATP So that’s where those 10,000,000 ATPs go! Well, not all of it! form cross bridge 11 1 3 release cross bridge Cleaving ATP ADP allows myosin 1 head to bind to actin filament shorten sarcomere 4 How it all works… • Action potential causes ______ release from SR – Ca2+ binds to _______ • Troponin moves __________uncovering _____________________ on ______ ATP • Myosin binds actin – uses ______ to "ratchet" each time – releases, "unratchets" & binds to next actin • Myosin pulls actin chain along • Sarcomere shortens – Z discs move closer together • Whole fiber shortens contraction! • Ca2+ pumps restore Ca2+ to SR relaxation! – pumps use ATP ATP Fueling Muscle Contraction • ATP is the ___________ source of energy for muscle contraction. Although a muscle fiber contains only enough ATP to power a few twitches, its ATP "pool" is replenished as needed. 3 sources of high-energy phosphate to keep the ATP pool filled. 1. _________________ 2. _________________ 3. _________________ in the mitochondria of the fibers. Creatine phosphate • The phosphate group in creatine phosphate is attached by a "high-energy" bond like that in ATP. • Creatine phosphate + ADP ↔ creatine + ATP • The pool of creatine phosphate in the fiber is about __________ larger than that of ATP and thus serves as a _________ __________ of ATP. Glycogen: storage of “sugar”? 2-D cross-sectional view of glycogen. A core protein of glycogenin is surrounded by branches of glucose units. The entire globular granule may contain approximately 30,000 glucose units.[1] Skeletal muscle fibers contain about 1% ____________. http://en.wikipedia.org/wiki/Glycogen Glycolysis • Breaking down glucose – “glyco – lysis” (splitting sugar) glucose pyruvate 2x 3C 6C – ancient pathway which harvests energy • where energy transfer first evolved • transfer energy from organic molecules to ATP • still is starting point for ALL cellular respiration – but it’s ____________ • generate only _________ for every 1 glucose – occurs in cytosol That’s not enough ATP for me! In the cytosol? Why does that make evolutionary sense? animals some fungi Lactic Acid Fermentation pyruvate lactic acid 3C NADH 3C NAD+ back to glycolysis _________________ once O2 is available, lactate is converted back to _________ by the _________ Count the carbons! O2 recycle NADH Why does hurt after you’ve worked out? Delayed Onset Soreness (DOMS), which is the soreness you feel a few hours to even a day or two after you workout. 1. MUSCLE ______________ This is okay, because your body will repair this damage and your muscles will actually become stronger because of it. However, it can be uncomfortable for some people -- especially if you aren't well-conditioned. 2. _______________ PRODCUTS -- Lactic acid build-up is actually responsible for the "burn" you feel in your muscle when you work it (especially at high reps), versus the muscle tenderness of DOMS. http://www.sportsinjurybulletin.com/arch… http://www.sciam.com/article.cfm?id=why-… • 2 years ago http://answers.yahoo.com/question/index?qid=20080210094842AAiEGg9 How do we get glucose fast? • The muscle fiber can degrade this glycogen by _________________producing glucose-1-phosphate. • The ______ is the main storage • of glucose and is controlled • by ______ and _______ • **** Negative feedback and Homeostasis Energy accounting of glycolysis 2 ATP 2 ADP glucose pyruvate 2x 3C 6C • Net gain = 4 ADP 4 ATP 2 NAD+ 2 All that work! And that’s all I get? But glucose has so much more ____________________ to give! – some energy investment (-2 ATP) – small energy return (4 ATP + 2 NADH) • 1 6C sugar 2 3C sugars Cellular respiration 2 ATP + 2 ATP + ~36 ATP Glycolysis: summary 1. __________________________ 2. _________ for each pair of lactic acid molecules produced 3. Not much, but enough to keep the muscle functioning if it fails to receive sufficient oxygen to meet its ATP needs by respiration. 4. However, this source is ________ and eventually the muscle must depend on cellular respiration. Cellular respiration is required • to meet the ATP needs of a muscle engaged in ___________________ (thus causing more rapid and deeper breathing) • • afterwards to enable the body to __________________ from the lactic acid produced earlier (________ ________ continues for a time after exercise is stopped). • The body must repay its ____________ ___________ http://breathing.com/tests.htm So why is respiration the last method muscles use to get the energy they need if it has the biggest gain? http://www.nismat.org/physcor/energy_supply.html It takes more time to produce ATP through respiration : glucose has to split in the cytosol and then get into the mitochondria Go through kreb’s cycle and then through etc Finally make 34 ATP if Oxygen is present Fig. 50-37 Energy cost (cal/kg•m) RESULTS Flying Running 102 10 1 Swimming 10–1 10–3 1 103 Body mass (g) 106 Type I vs. Type II Fibers Type 1 : _________ _______ Type 2: _________ ________ Reality we are comprised of both Type I Fibers also known as "slow-twitch" fibers 1. loaded with ______________ 2. depend on _______________ for ATP 3. _________ the major energy source 4. resistant to ___________ • rich in _________ (red in color= the "dark" meat of the turkey) • activated by small-diameter, thus ________________, motor neurons • dominant in muscles used in activities requiring endurance (leg muscles) and those that depend on tonus, e.g., those responsible for posture Myoglobin is the primary ________________ pigment of muscle tissues. SO WHY DO MUSCLES NEED Mb WHEN THEY HAVE Hb? Unlike hemoglobin, Mb does not exhibit cooperative binding of oxygen, since positive cooperativity is a property of multimeric/oligomeric proteins only Instead, the binding of oxygen by myoglobin is ______________ by the oxygen pressure in the surrounding tissue. Myoglobin is often cited as having an "instant binding tenacity" to oxygen. Mb binds to O2 when O2 is plentiful and _________ O2 when concentrations are low High concentrations of myoglobin in muscle cells allow organisms to hold their breaths longer. http://en.wikipedia.org/wiki/Myoglobin Myoglobin contains a heme group which contains a central iron atom, usually in the +2 oxidation state. The colour of myoglobin is determined by whatever the iron atom is bonded to: 1. if it's bonded to an O2 molecule, the myoglobin is ____________, 2. whereas in the absense of oxygen it bonds to water and is a ________ 3. If the iron atom becomes oxidized, or loses an electron, the myoglobin turns _________ This can happen after a prolonged time _________access to oxygen, or in an ________environment. When meat is cooked, some of the proteins in it denature and become opaque, turning red meat pink. At 60 degrees C, the myoglobin itself ____________and becomes tan-coloured, giving well done meat a brownish-grey colour. Freezing for long periods of time can also denature the myoglobin. Finally, curing meat can cause other molecules to bond to myoglobin. Type IIb Fibers • • • • • _______ mitochondria rich in ______________ depend on ________ _________ and ________ for ATP fatigue e_________ with the production of lactic acid ______ in myoglobin hence whitish in color (the white meat of the turkey) • activated ___________________, thus ____conducting, motor neurons • also known as "fast-twitch" fibers • dominant in muscles used for rapid movement, e.g., those moving the eyeballs. Fast twitch & slow twitch muscles • _____________________ – _________, but keep going for a long time • more mitochondria for aerobic respiration • less SR Ca2+ remains in cytosol longer – _______________ – “dark” meat = more blood vessels • ______________________ – ____________, but get tired rapidly • store more glycogen for anaerobic respiration – ______________ – “white” meat Muscle limits • ____________________ – lack of sugar • lack of ATP to restore Ca2+ gradient – low O2 • lactic acid drops pH which interferes with protein function – synaptic fatigue (failure of nerve impulse) • loss of acetylcholine • ___________________ – build up of lactic acid – ATP depletion – ion imbalance • massage or stretching increases circulation Recovery: oxygen consumption after exercise Increased breathing rate – enhanced O2 delivery • • • • “oxygen debt”: add O2 over and above O2 consumed when resting 1. be able to convert lactic acid back to glycogen (liver) 2. resynthesize _____ and ______ 3. replace _____ removed from _____ Use O2 1. Increased body temp = inc. chem rate of reaction = inc. ATP metabolism 2. Heart muscles work harder 3. Tissue repair at __________ ________ Does Lance Armstrong break the rules? Blood doping? http://whyfiles.org/090doping_sport/3.html http://en.wikipedia.org/wiki/Lance_Armstrong Physical attributes 1. an aerobic capacity of 83.8 mL/kg/min (VO2 Max),[9][10] higher than the average person (40-50), but lower than other Tour De France winners, Miguel Indurain (88.0, although reports exist that Indurain tested at 92-94) and Greg LeMond (92.5).[11] 2. He has a resting heart rate of 32-34 beats per minute (bpm) with a maximum heart rate of 201 bpm.[12]