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3-03-10 I am what I do- The muscles and Bones-color

3-03-10 I am what I do- The muscles and Bones-color -...

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Unformatted text preview: Clicker Question Advanced glycated end-products end(AGEs) are a result of _______________. A) B) C) D) E) a deficiency in vitamin B1 a deficiency in vitamin B3 too much glucose in the blood an excess of vitamin KKproducing bacteria in the gut an unusually long rectum Spend your SUMMER on an island in Maine! www.sml.cornell.edu courses and internships financial aid available Where are we? • We have finished discussing: I am alive, I am what I eat, I am what I don’t excrete, I am stable and metastable, metastable, and I age. age. Today I will talk about: will talk about: I am what I do. do. The Biology of Muscle and Bone. Anatomy, Anatomy, physiology, levers, thermogenesis and basal metabolic rate. • • Next time we will begin talking about: I am my genes and I am a work in progress. progress. Reproduction and Development. www.dosomething.org I am what I do On February 23, 2010, David Benke, Benke, a math teacher and Becky Brown, an assistant principal, with prepared minds and courage, saved the the lives of their students at the Deer Creek Middle School in Littleton, Colorado when they grabbed an armed shooter named Bruco Strong Eagle Eastwood and his gun. Profiles in Courage Award In whatever arena of life one may meet the challenge of courage… courage each…must decide for himself the course he will follow…. —John F. Kennedy Profiles Profiles in Courage 1 A Profile in Courage Anchors and Motors When we study the movements of muscles, we must remember the admonitions of Aristotle in The Movement of Animals: Plant and animal cell biologist Werner Franke exposed illegal East German steroid research and the illegal doping of athletes. depends on the nonnonmovement of an adjoining part. Thus in order to have motion motion, there must be an anchor that is capable of providing resistance to resistance motion.” “The movement of one part movement of Archimedes realized the importance of an anchor anchor when using a lever when he said, “Give me a place to stand— stand—and I shall move the world.” Metaphorically speaking, I hope Cornell gives you that place to stand and the reason and means to move the world world. Ithaca by C. P. Cavafy Ithaca As you set out for Ithaca hope your road is a long one, full of adventure, full of discovery…. C. P. Cavafy, Poet Ithaca recited by Sean Connery Cornell Commencement Frank Rhodes, Cornell Sean Connery, Actor 2 The Skeletal System Anchors the Muscles • In order for muscles to do work, they must be anchored. The anchored muscles that are anchored to the skeleton are called skeletal skeletal muscles In general they are muscles. In general, they are anchored anchored to the skeletal system by tendons. tendons The architecture of the human skeletal system has been known since ancient times—because the times— bones are stable structures that do not rapidly decompose. • see something of human bones. I have done so often on the breaking open of a tomb or grave. Thus once a river, inundating river, inundating a recently recently made grave, broke it up and swept away the body of the dead man. The flesh had putrefied, but the the bones still held together in their proper relations.” According to Galen (100 AD), “It is possible to Leonardo Da Vinci Studied the Relationship between Muscles, Tendons and Bones Anchors and Motors Versalius Versalius Bones • The rigid bones are composed of living cells that secrete a thick • made of the protein th collagen collagen and calcium calcium phosphate. The bones participate in the homeostasis of homeostasis calcium. extracellular extracellular matrix 3 The Kidney Secretes EPO, which Stimulates the Production of RBCs from the Common Myeloid Progenitor Cells in the Bone Marrow The bones can break, heal, be replaced and even replaced and even sell sell jeans. http://streetanatomy.com www.breakthecycle.org www.ovw.usdoj.gov 4 Osteoporosis Osteoporosis, which occurs when the rate of calcium loss is greater than the rate of calcium gain, can be prevented with calcium, vitamin D, and exercise. Diet is important for healthy bones. Muscles www.boniva.com www.bonehealth.com There are Three Classes of Muscle in the Body • Skeletal: Voluntary muscles (that respond to and perform your intent or will). • Cardiac: Heart muscle (responds to emotions). • Smooth: Most sphincters, muscle surrounding the alimentary canal and blood vessels (respond to emotions). • In general, all muscles are similar although details of regulation and structure differ. There are Two Basic Conditions of Living Matter: Activity and Relaxation • Muscular movement requires both. • Muscle contraction is an active process contraction an active that requires ATP hydrolysis. • Muscle extension or relaxation is a passive process. 5 Movement Requires the Interaction of Opposing Muscles • Movement requires the • • coordinated coordinated actions of two opposing muscles. opposing One muscle in a pair pair relaxes while the other while muscle contracts. contracts The nervous system nervous provides the signal for a muscle to contract. Skeletal Muscle is Under Control of the Central Nervous System The Biomechanics of Movement • Together, the muscles and the bones provide torque the torque necessary for accomplishing mundane and spectacular feats and spectacular feats. Torque is the ability to lever (bone) rotate a lever (bone) fulcrum around a fulcrum (joint). (joint). A fulcrum is a point of fulcrum is support. • The greater the number of neurons innervating the muscle, the finer the degree of motor control. • The Body as a Machine: Levers • A lever iis a rigid bar that rotates lever s • Levers can be arranged to minimize minimize around a fulcrum. fulcrum Examples of Levers in Our Body • First and second class levers allow us effort or maximize speed and range speed range of motion. • to do something with less effort. The mechanical advantage [dforce/dload > 1] gives us more strength. gives A third class lever allows us to move with greater speed and with a greater range of motion. However, as a result of the mechanical disadvantage mechanical [dforce/dload < 1], the action takes more takes more strength. 6 Muscle, Joints and Bones as Levers Formula and Sign Convention for Levers Assume Rotation = 0 Rotation = (Load) (distanceL) + (Effort) (distanceE) = 0 • First Class – distanceE < 0 – Load, Effort and distanceL > 0 – Mechanical Advantage (L/E) = -dE/dL Advantage (L/E) FirstFirst-Class Lever: Head The head is an example head is of a first-class lever first(like (like a seesaw). The fulcrum is fulcrum is the atlas bone and the muscles in bone and the muscles in the the back of the neck provide the force. The front of the head is the load, which falls forward when you are too tired to voluntarily contract the muscles in the back of your neck. • Second Class – Effort < 0 – Load, dL and dE > 0 – Mechanical Advantage (L/E) = -dE/dL • Third Class – Load > 0 – Effort, dL and dE < 0 – Mechanical Disadvantage (E/L) = -dL/dE Levers in the Human Body SecondSecond-Class Levers • Standing on tiptoes is an • example of a second-class secondlever (like a wheelbarrow). When standing on tiptoes, the toe is the fulcrum the the toe is the fulcrum, the whole whole body is the load and calf muscle provides the force. The mechanical mechanical advantage of this lever allows us to lift our entire body with the force generated by just one muscle. ThirdThird-Class Levers: Most Common in Body • The arm, like most joints in thirdthe body, is a third-class lever. In the arm, the elbow fulcrum is the fulcrum, the hand (and its contents) are the load and its contents) are the load and the the biceps provide the force. The mechanical mechanical disadvantage of this lever gives us a tremendous tremendous range of motion which contributes to letting pitchers pitch a baseball over 100 mph. • • Sports Science 7 The Fingers are Third Class Levers with Large Ranges of Motion Levers Levers Used for Physical Comedy Groucho in the mirror Harpo playing the harp Chico playing the piano Harpo and Chico play the piano Chico playing the Blue Danube Chico plays the piano with an apple Charlie Chaplin Used Levers for Physical Comedy We Use Our Muscles to Express Emotions through Body Language • Guillaume Duchenne (1862) electrically stimulated the faces of his subjects and determined that a real smile, now known as a Duchenne Duchenne smile, involves the movement of the zygomaticus movement of the zygomaticus major major muscle near the mouth and orbicularis the orbicularis oculi muscle near the eye. His subject was “an old toothless “an • Charlie Chaplin....Table Ballet man, with a thin face, whose features, without being absolutely ugly, approached ordinary triviality….I could stimulate his individual muscles with as much precision and accuracy as if I were working with a still irritable cadaver.” The Muscles of Emotion • Duchenne compared the artificial expressions evoked by electrically stimulating various facial muscles with those evoked by natural stimuli. Duchenne determined which facial muscles were involved in the natural expressions of attention, reflection, aggression, pain, joy, lasciviousness, sadness, surprise and fright. Which muscles do you typically exercise? There are Similarities in the Movements of Facial Muscles Used to Express Emotions in Humans and Animals • • 1872 8 Does it Take More Muscles to Frown than to Smile? Twelve Muscles Involved in Smiling • The two zygomaticus major and zygomaticus • • • • two zygomaticus minor muscles zygomaticus contract to pull up the corners of the mouth. Two orbicularis oculi muscles orbicularis cause cause the crinkling of both eyes. Two levator labii superioris levator muscles pull up the corners of lip and nose. Two levator anguli oris muscles levator elevate the angle of mouth. Two risorius muscles pull the risorius muscles corners of the mouth to the side. Nine Muscles Involved in Frowning • The two corrugator supercilii corrugator • • • • and one procerus furrow the procerus brow. The orbicularis oris purses the orbicularis lips. The two platysma pull down the platysma pull lips and wrinkle the skin of the lower face. The mentalis depresses the lower mentalis depresses lip. The two depressor anguli oris depressor muscles pull the corners of the mouth down. The Way I See it, Smiling is Still Worth it! Biological Individuality—Smiles Individuality— 9 Nutrition and Facial Muscles In this example of performance art, the human facial muscles are controlled by controlled by a computer through electrical stimulation. Arthur Elsenaar is both the artist and the “display device.” artifacial.org Skeletal Muscle: Carnivores Really Are What We Eat Muscle Composition and Structure • The muscle consists of a • bundle of multi-nucleate cells multiknown as muscle fibers. muscle The muscle fibers contain myofibrils, which are fib il actomyosin composed of actomyosin, a actin mixture of two proteins, actin and myosin. myosin Inside the muscle fibers, the actin and myosin are oriented in repeating units called sarcomeres sarcomeres. • Sarcomeres of Skeletal Muscle The sarcomeres of sarcomeres skeletal muscle are aligned to aligned to give a striated striped striated or striped appearance. Muscle tissue is often called striated or striped muscle. The alignment allows the coordinated movement of each sarcomere to give the muscle more speed and more force. Movement is a Characteristic of All Life Movement is one of the most easily distinguished characteristics of life. Theodor Engelmann (1879) noticed all kinds of motion in plants and kinds of motion in plants and protozoa, including amoeboid movement and cytoplasmic streaming. He suggested that these activities may be a primitive version of the specialized movements that occur in muscle and the same molecular mechanisms may be involved in them all. 10 Albert Szent-Györgyi (1949) Szentput it this way: “All living organisms are but leaves on the same tree of life. The various functions of plants and animals and their specialized organs are specialized organs are manifestations manifestations of the same living matter. This adapts itself to different jobs and circumstances, but operates on the same basic principles. Muscle contraction is only one of these adaptations.” Which Which is the best motile process to study? If all life shows motion, which cell, tissue, organ or organism shall we choose to study in order to unravel the mysteries that underlie the vital process of movement, and to give us the most clear and profound answers? Szent-Györgyi suggests that we use the cells that are most specialized for movement—skeletal muscle cells. Decision Decision not to follow the Scientific Fashion of the 1930s While most most 1930s were studying Muscle Protein (Myosin) can Hydrolyze ATP • In those days, the residue or precipitate was thought to be composed of mundane structural proteins (like the collagen and keratin proteins collagen and keratin proteins of of skin, fingernails, hooves and hair) and not exciting enzymes. But, by not following the current current fashion in science, Engelhardt and Lyubimova found that myosin, in the residue of muscle, was an enzyme capable of hydrolyzing ATP. biochemists in the and and wife team of Vladimir Engelhardt and Militza Lyubimova waterwater-soluble enzymes the husband enzymes, the husband violated violated one of the canons of biochemistry, and studied the “residue instead of the extract.” • SzentSzent-Gyorgyi Guessed that Myosin was the Mechanochemical Transducer Albert Szent-Györgyi thought that myosin may be the mechanochemical be the mechanochemical How do you Start? transducer that coupled the chemical energy of ATP to the mechanical energy of contraction, and he set out to test his hypothesis. “If you go into a new field, the question is…How do you start?...repeat…classical old work. The old scientists—they didn’t have many machines, but they were very good observers and watched the material very closely. So you can repeat these old experiments…and see whether you find something new for yourself. My work is composed of enormous philosophical ideas and what is at my fingertips, smelling it, watching all the small details.” 11 How do you Start when you Enter a New Field? • So with a prepared mind as well as a nose and Seeing Life Itself fingertips prepared to discover something new discover something new, Szent-Györgyi repeated the work of the “old masters” and isolated myosin. solution to get the typical syrupy myosin preparation. • He then prepared threads of myosin and put them on a slide and watched them under a microscope (A). When he added ATP to the slide, they contracted (B)! It was as if he had seen life itself! • He extracted the muscle for an hour with a salt • Discovery of Actin Ilona Banga continued to isolate myosin in SzentGyörgyi’s laboratory, but she had to go home early one day and accidentally and accidentally left the the minced muscle in salt solution all night. The next morning they realized that the extract was thicker than the usual extract and it also Albert SzentAlbert Szent-Gyorgyi “A discovery is said to be an accident meeting accident meeting a prepared mind." prepared -Albert Szent-Gyorgyi Szent- contracted more vigorously upon the addition of ATP. The Discovery of an Actor: Actin • Szent-Gyorgyi postulated that the thick • • • • extract contained a protein contaminant. Ferenc Straub removed the myosin from the muscle with a salt solution and then he dried the remaining muscle. Then he added water to the dried muscle powder, a protein went into solution. This protein, when added to myosin in the presence of ATP, caused the myosin to contract. Szent-Gyorgyi and Straub named this protein actin, because it had the ability to act on myosin. Together, actin and myosin, which is also known as actomyosin, contract in response to ATP. SzentSzent-Gyorgyi Introduces Cell Models • In order to test if his test tube biochemical conclusions were valid in cells, Szent-Györgyi created a cell model in which he permeablized the cell membrane so ATP could enter. ll ATP -ATP • Upon addition of ATP, the cell model contracted as if it were an intact muscle. He concluded that contraction is due to the transformation of the chemical energy of ATP to the mechanical energy of muscle contraction. +ATP 12 Measuring the “contraction” of actomyosin of actomyosin in Szentin SzentGyorgyi’s lab ATP Fuels Muscle Contraction • Szent-Györgyi concluded that the chemical energy of ATP provided the energy for muscle contraction, and that muscle contraction could be explained simply by the interaction of actomyosin and ATP. Was his conclusion simple or simplistic? • http://profiles.nlm.nih.gov/WG/Views/Exhibit/narrative/institute.html Eva Szent-Gyorgyi A Violation of the First Law of Thermodynamics? • This conclusion was not accepted by Archibald V. Hill because the measured amount of ATP hydrolyzed during contraction of living muscle living muscle was insufficient insufficient to account for the work performed by the contracting muscle. This meant that Szent-Gyorgyi’s Szentconclusion violated the First First since the work done would be greater than the energy used. Archibald V. Hill and Exercise Science Archibald V. Hill (1927) at Cornell • Law of Thermodynamics Creatine Phosphate (Phosphagen) Regenerates ATP The apparent fact that the amount of ATP hydrolyzed was insufficient to account for the work performed by the muscle was due to the fact th ATP that ATP is regenerated through a creatine phosphate system in the muscle and in fact the amount of ATP hydrolyzed does account for the amount of work the muscle does. Thus Szent-Gyorgyi’s idea that ATP provided the energy for muscle contraction really did not violate the First Law of Thermodynamics. 13 Elastic Contraction vs. Sliding • From the first observation of the contraction of actomyosin threads under the microscope, Szent-Györgyi believed that the proteins themselves contracted lik like an elastic band. However better microscopic data obtained by Jean Hanson, Hugh Huxley and Andrew Huxley, indicated that the contractile proteins were not contractile at all, but slide past each other when they effected the contraction of a muscle. Even Even Heroes Make Mistakes “One who doesn’t work makes no mistakes.” mistakes.” -Albert Szent-Gyorgyi Szent(1941) to Ferenc Guba when Guba broke a piece of equipment soon after joining Szent-Gyorgyi’s lab. Szent…and you know that good science is often the result of making a mistake. But then again only • Studying the Sarcomere with Polarized Light Microscopy Theodor Engelmann observed that the sarcomeres, which were separated by the “in between bands” or Z-bands (zwichen-bands) were bright under a polarizing microscope. ReRe-naming the Bands Engelmann’s observations were repeated by the structural biologists in the structural biologists in the 1950s, including Andrew Fielding Huxley. Huxley named the bright band the A-band (meaning anisotropic) and the large dark areas, the I-bands (meaning isotropic). Andrew, Andrew, T. H. and Julian, and Aldous Huxley, author of Brave New World Localization of Myosin and Actin in the A bands and I bands • Light microscopical studies showed that treating the muscle fibers with high salt, which caused the extraction of myosin, simultaneously resulted in the simultaneously resulted in the disappearance of the A-bands! Longer extractions, which resulted in the subsequent loss of actin, caused the I-bands to disappear. These results indicated that the A • • Interview with A. F. Huxley bands were composed of myosin and the I bands were composed of actin. 14 Myosin Forms Thick Filaments and Actin Forms Thin Filaments • Electron microscopy done by Hugh Huxley and Jean Hanson showed that the myosin in the A-band formed thick filaments and the actin in the I-bands formed thin filaments. • The thick filaments also contained globular regions, some of which made crossbridges with the thin filaments. The Sliding Filament Model of Contraction • During contraction, the length of the A bands stay the same. • During contraction, the length of the I-bands decreases decreases. Fat • These data were interpreted by contraction occurs when the thin filaments slide past the thick filaments. Jean Hanson and the two unrelated Huxleys to mean that the contractile proteins remain constant in length, and Details Details of the Sliding Filament Model • The sliding filament model became universally accepted and Szent-Gyorgyi’s original idea that actomyosin contracted like rubber band was abandoned like a rubber band was abandoned. Subsequently, biophysicists have worked to understand how the chemical energy of ATP is converted into the mechanical energy of actomyosin in order for the myosin molecule to generate movement along the actin filament. http://www.getbodysmart.com/ap/muscletissue/contraction/multipleheads/tutorial.html • 15 Actin, Myosin and ATP • Myosin binds ATP and separates • Myosin hydrolyzes the ATP and from actin. undergoes a conformational change so that the head is adjacent to the next actin monomer monomer. Myosin releases the terminal phosphate of the ATP and binds actin tightly. The tight binding between the actin and the myosin initiates a ratcheting of the myosin molecule that results in the power power stroke and the release of ADP. Life Life and ATP • • The myosin head continues to bind tightly to the actin filament until it binds another molecule of ATP, and rowing the rowing motion continues as the myosin moves from one end of an actin filament to the other. Unless…. Rigor Mortis • …a cell dies, and no no • Then the myosin head Then the myosin head can can no longer dissociate from the actin filament and the cell becomes stiff and inelastic, a state rigor known as rigor Not All Skeletal Muscles Are the Same longer produces ATP. mortis. Types of Skeletal Muscle • Skeletal muscle • Slow twitch Sl • • Fast twitch (striated, striped, voluntary muscle) Slow Twitch Skeletal Muscle (Rich in Dark Meat) • Slow contraction time time • high (~100 ms), but high endurance. Reddish, because they contain myoglobin (an myog bi oxygen carrier in muscle, similar to hemoglobin) Lots of capillaries and capillaries mitochondria mitochondria for aerobic respiration Higher fat content for long fat term energy demand muscle muscle (~50% in average person) Intermediate muscle (~50% in average person) • • 16 Fast Twitch Skeletal Muscle (Rich in White Meat) • Fast contraction time low (~50 ms), but low endurance. • Whitish (they do NOT Slow and Fast Twitch Muscles • Slow twitch muscle contracts continuously continuously because an almost unlimited supply of almost oxygen necessary to make ATP by aerobic respiration comes from the blood, but contraction is slow because the rate of oxygen slow delivery by the cardiovascular system can not delivery by the cardiovascular system can not keep keep up with the faster demand by the mitochondria in the muscles. Fast twitch muscles contract quickly because quickly because the myofibril does not have to wait for the oxygen to come from the cardiovascular system but contraction cannot continue for long because not enough ATPs are made by anaerobic respiration to keep up with a long term demand. • Fewer capillaries and contain myoglobin) • mitochondria (cell must rely on anaerobic anaerobic fueled respiration fueled by the breakdown of glycogen) The The Things You Find on the Web Nature: Genetic Predisposition • Average person has 50% slow twitch and 50% • Marathon runners have 80% slow twitch and • Sprinters have 20% slow twitch and 80% fast have • Proportion can be changed somewhat by exercise (nurture). – Aerobic exercise makes the intermediate cells more like slow twitch fibers and power training makes power them more like fast twitch fibers. fast twitch skeletal muscles. 20% fast twitch skeletal muscles 20% fast twitch skeletal muscles. twitch skeletal muscles. Nurture: Exercise and Training • Aerobic Exercise (endurance training) – Increases the number and size number of mitochondria in muscle fibers, as well as increased increased blood flow to muscle for more blood flow to muscle for more aerobic aerobic ATP formation. Muscle Pain • Lactic acid buildup in both fast and both short slow twitch muscles causes short known muscle term pain known as muscle burn. Lactic acid builds up in slow twitch muscles when not enough oxygen can be delivered for aerobic respiration be delivered for aerobic respiration. inflammation that results from delayed delayed pain. The microscopic tears power training also leads to a result in the muscle being rebuilt with more mass and bulk so they are better prepared for the next strenuous use. www.bioflexmagnets.com • Anaerobic Exercise (power training) – Increases amount of amount actomyosin in and size of muscle fibers. – More glycogen is stored in muscle for more anaerobic ATP formation. • Microscopic tears and 17 Muscles Grow and Repair Themselves through the Addition of Satellite Cells Increasing the Mass of Muscle Cells • When multinucleate muscle fibers are injured, they secrete a chemical signal (Insulin(Insulin-like Growth FactorFactor1; IGF 1; IGF-1) that attracts that attracts satellite satellite cells. The satellite cells multiply and fuse with the muscle fibers. This results in the formation of more myofibrils in the repaired muscle fiber and an increase increase in muscle mass. • • A Natural Mutation Increases the Muscle Mass in A Belgian Blue Bull • The Proliferation of Satellite Cells Can be Accomplished in Many Ways • The mutation in the Belgian Blue Bulls results in the production of a defective myostatin protein. myostatin protein. Myostatin is a protein that • The proliferation of satellite cells can be accomplished by increasing IGF-1, decreasing IGFmyostatin myostatin or by applying a myostatin myostatin inhibitor. Lee and Sweeney interview inhibits the proliferation of th satellite satellite cells. Muscular Dystrophy • Muscular dystrophy is • characterized by a progressive degeneration of muscle fibers. Pharmaceutical companies Pharmaceutical companies are are developing myostatin myostatin inhibitors to inhibit the inhibitor of muscle growth and thereby reverse the muscle degeneration characteristic of muscular dystrophy. acceleronpharma.com amgen.com wyeth.com Myostatin Inhibitors (Cystoseira canariensis— canariensis—a brown alga) Sold to Athletes to Increase Muscle Mass 18 Whippets Can Have Mutations in the Myostatin Gene that Is Correlated with Making Them Better Runners A Mutation in the Myostatin Gene in Humans • A boy in Germany was recently born with a mutation in his myostatin gene his myostatin gene. Here is how his leg looked when he was 7 months old. • Lee and Sweeney interview MyostatinMyostatin-Related Mutations also Exist in Humans • Liam Hoekstra’s satellite • cells do not respond to the normal myostatin that he produces. Consequently, his satellite Consequently, his satellite cells cells uninhibitedly proliferate and fuse with his muscle fibers. He has 40% more muscle mass than his friends. He could do gymnastics when he was five months old. Hard Work Increases the Amount of Muscle in a Rower’s Back • Who Has the Unfair Advantage? • According to H. Lee Sweeney, "There are going to be people who are carrying these mutations that give them unusual athletic abilities without the need to do the same level of training as an average person. If I was a weightlifter and competing against someone who is not making any myostatin because of mutation in his any myostatin because of a mutation in his genes, genes, then I think I might want to file a protest unfair that that person has an unfair genetic advantage even though they inherited it." Know Know Thyself • "I think as this becomes more widely known that athletes are competing against people who have naturally occurring mutations that are clearly a genetic genetic advantage to them, that they're going to say that this gene enhancement or gene gene doping is not an unfair thing." 19 What is the Future of Human Nature? • Know thyself. Who are we, • and what is our human nature? Are the genes we are born with part of the definition of who we are and do we want to accept this as gift and to accept this as a gift and rejoice rejoice in the genes we were born with? Are we defined by something other than our genes and do we not want to settle for the genes we were born with, but rather trade up for ones that will make us more like our true selves? Gene Therapy • Gene therapy can be used to express high levels of IGF-1 or IGFinhibit the production of or response to myostatin. Any of these therapies will lead to the these therapies will lead to the production more production of more muscle mass. Gene therapy can also be used to convert muscle cells into the slow slow twitch muscle cells that are good for endurance or fast fast twitch muscle cells that are good for sprinters. • • www.betterhumans.com In Just Seven Days…I Can Make You a Man. What is the Future of Human Nature? World Anti-Doping Agency Thermogenesis • Skeletal muscle tissue makes up the majority of the body weight and generates the majority of the majority body heat. During cold weather, additional heat is generated from rapid contractions which we call shivering shivering. The heat generated is proportional to the heat volume of the muscle (m3). th The heat radiated is proportional to the surface heat surface area of the organism (m2). The surface to volume ratio of a spherical surface organism with radius r is: S/V = (4πr2)/(4πr3/3) = S/V (4 • • • • Thus one of the reasons that warm-blooded warm- 3/r 3/r organisms cannot grow infinitely large is that they cannot would burn up in warm weather. 20 Why do some people burn Calories better than others? Recitation of Pi HR 224 The Basal Metabolic Rate (BMR) or the rate in Basal which Calories are burned at rest depends on a person’s proportion of muscle and fat. proportion Basal Metabolic Rate (BMR) • At rest, the average • person burns about 1600 Calories/day. At rest, each pound of muscle burns muscle over 13 Calories/day. At rest, each pound fat burns of fat burns less than 3 Calories/day. Average Height and Weight Now it’s time for you to use your muscles. • 21 ...
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