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Cardio KIN 2CC3 lecture Jan 14.pdf

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McMaster University
Krista Howarth

Cardiorespiratory KIN 2CC3 Lectures Major Tissues in exercise metabolism:▯ - Lungs▯ ❖ supplies oxygen to heart and circulation▯ - heart and circulation▯ - skeletal muscle - causes the demand for energy, dictates change in everything else▯ ❖ requires fuel and oxygen from heart/circulation▯ ❖ we are using oxygen to break down the fuels that our body needs to keep going▯ ❖ produces: metabolic by-products = carbon dioxide, heat, la etc.. — these get transferred away from skeletal muscle▯ ❖ lactic acid byproduct: can change the pH which isn’t good for the system▯ Minor Tissues:▯ - supply tissues: fuels to heart and circulation ▯ ❖ liver (glycogen)▯ ❖ adipose tissue (triglycerides)▯ ❖ skeletal muscle (conserves own energy so readily available)▯ - removal tissues: removal of byproducts▯ ❖ skin (red faces - increased blood flow dissipates heat)▯ ❖ liver (lactic acid - converts to glucose)▯ ❖ heart (likes to use lactate as energy)▯ *** as you train, some muscle fibres can use lactate▯ ▯ ENERGY PRODUCTION▯ “Bioenergetics” - energy transfer in the body▯ **REVIEW** 3 main sites we need energy for:▯ 1. sarcoplasmic reticulum (pumps calcium)▯ 2. myosin heads (allows CBs to move)▯ 3. sodium potassium pump▯ ▯ ATP▯ - when broken down it releases energy▯ - we need to constantly rebuild it ▯ ❖ Fuel —> energy —> work▯ bioenergetics: the study of energy transfer via chemical reactions in living tissues▯ ▯ 1. ENERGY TRANSFER: thermodynamics▯ ❖ heat energy, chemical, mechanical, electrical▯ ❖ 1st law: energy cannot be crested nor destroyed, only transferred from one form to another▯ ❖ ∆E = Usable E + Non-usable E▯ ❖ usable: 40% free energy helping drive energy sites▯ ❖ nonusable: 60% heat▯ Reaction: A —> B▯ ❖ ∆E = 100 units of energy released▯ ❖ some is used for work, rest lost as heat▯ ❖ now we need to put in 100units of energy to use A again, this comes from external fuel source▯ ❖ ATP produces energy, BUT in order to keep it as ATP - we need to keep supplying energy to recreate it▯ ✦ ATP▯ Cardiorespiratory KIN 2CC3 Lectures ❖ adenine + ribose (adenosine), phosphates (high energy)▯ ❖ the hydrolysis reaction that breaks phosphate bonds releases this energy▯ ❖ sometimes we turn it into AMP but not regularly bc its harder to make back into ATP, happens in things such as marathons - ADP —> AMP▯ ATP in ENERGY TRANSFER▯ Fuel gives us energy through ATP —> ADP, causes fuel byproducts▯ - some molecules of fuel can be completely broken down in presence of oxygen ▯ ❖ this would cause CO2 and water byproducts▯ - fuel systems that take more steps to be broken down give us MORE energy▯ ▯ FUEL SOURCES USED TO REGENERATE ATP in the BODY▯ 1. Phosphocreatine (PCr) (small source)▯ 2. Carbohydrates (main source)▯ 3. Fats (main source)▯ 4. Proteins (not ideal for fuel bc byproduct is ketones, and muscle can break down, only used in emergency)▯ ▯ why don’t we store a ton of ATP in our body???▯ - we use 1 kg of ATP per hour at rest, increases 100-fold during exercise▯ - instead of storing it, we regenerate. molecule is too large to store▯ ATP supplements?▯ - $100 for 1g (20x50mg) bottle▯ ❖ that would last you 0.04 seconds of energy▯ Supplements▯ - purity▯ - digestive system functioning▯ - delivered in blood to the target tissue?▯ __________________________________________________________▯ ▯ 2. CHEMICAL REACTIONS▯ key: ENZYMES▯ ❖ proteins that increase the rate of chemical reaction (don’t cause the reaction)▯ ❖ do not alter the free energy change▯ ❖ “catalyst”▯ ❖ they lower the activation energy required to break a substrate down into its product▯ - breaking down fuels substrate—> product = releases energy▯ - the amount of activation energy required dictates the speed of the reaction▯ ❖ enzyme lowers the activation energy (the peak) before substrate can turn into product▯ ▯ Enzyme Mechanism of Action▯ - enzymes have a binding site (active site) contacts substrate —> each individual active site can only bind to a specific substrate “lock and key”▯ - E-S complex = transition state. enzyme is creating an environment to rearrange the chemical bonds to help turn it into the product. these changes could occur naturally, enzyme just speeds it up.▯ - after bonds are changing etc… this becomes the product. ▯ - enzyme does not change at all in the process▯ ▯ Factors Affecting Enzyme Activity▯ Cardiorespiratory KIN 2CC3 Lectures 1. substrate concentration ▯ ❖ amount of substrate available to the enzyme▯ 2. modulator▯ ❖ can speed up rate of enzyme activity, or slow it down▯ ❖ EX: ADP. acts as a signal to say that ATP is being used, lots of cause signals enzymes to get to work▯ 3. temperature▯ 4. pH▯ ▯ ✦ Substrate Concentration▯ - as we increase concentration, velocity increases rapidly initially and then levels out at Vmax = maximum rate of reaction▯ - Vmax is dictated by completely saturated enzymes - all bound to a specific substrate (causes a waiting line)▯ ▯ ✦ Modulators: stimulators and inhibitors▯ - change the shap
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