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Org Phys Lect sept 20.docx

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Western University
Biology 2601A/B

Org Phys Lect Sept 20 Energy: The capacity to do work A wave is not an object coming toward you, it is energy moving through the surface of the ocean as a wave Metabolism: Metabolism is the entire process Energy Metabolism: 2 categories; one where you destroy things (catabolic) one where you build things (anabolic) Law of thermodynamics First law: energy cannot be created or destroyed, it can only change forms (idea that its conserved) - sitting on the beach and you see a wave hit the beach, where has the energy gone? Heat and sound (nrg gets changed in terms of its form) second law: entropy (randomness) always increases claw pic energy has a capacity to increase order why is energy so important to organisms you have to eat all the time why do we always need energy? We need it to maintain our body temperature and to keep organized Pics are the development of a sea star (sea urchin), when you grow and you undergo your organized process you come to your adult stage Our bodies are always changing, the atoms are constantly being exchanged with our environments (our red blood cells die every 4 days and then are replaced), every atom in our bodies are being replaced at some rate This is what takes a considerable amount of energy Star fish page When you die your energy is all taken away from you, the entropy of your atoms go into the earth Animals are not isolated systems, they need energy from the outside world, we are not static (like the perpetual motion machine) we need some kind of input. Energy exists in different forms: 4 different forms chemical energy; atp or gucose electrical energy; cells set up currents across membranes mechanical energy; just the movement of a limb, your heart pumping and pushing your blood around heat; random motion of atoms and molecules we’re not all equal at doing work divide these forms of energy into two components high grade energy; the chemical energy, electrical energy, and mechanical energy low grade; not capable of doing any kind of physiological work, heat. - is there any way heat can actually do work in our body? Heat cannot be used to do work in organisms Why does heat dissipate? Because of conduction Cant do work; you cant set up a great differential gradient between zones or areas of your body Within organisms, energy can be transformed form one form into another cheetah slide Eat your meal, get chemical energy, that energy can be released at the level of muscle, mscle will burn atp, burn that fuel, use that fuel to transform into mechanical work. Always going to be heat loss from that Not 100% efficient slide Cheetah is eating meat, protein is being moved to chemical energy atp, atp
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