Lecture 1, Introduction to Energy Transfer Flashcards
Energy - The Capacity for Work
- as biologic work increases, energy transfer increases (energy can be hard to measure unless it is is transferred)
- biologic work is expressed in mechanical units
- emerges only when a change takes place
- energy can be thought of as stored work
Bioenergetics
transfer of energy in biological systems that can be people (how we transfer energy from our environment through our bodies to do useful work like running up a hill, lifting a weight)
- flow and energy exchange within a living system
Work
work = force x distance
- can calculate work with our bodies - easy to calculate work if we are going up a stair or a steep hill (body mass x height increase)
- cycle = distance wheel has travelled x amount of weight on wheel
- work is independent of time (as you are doing the exact amount of work but what changes is the power)
Power
power = work / time (or work rate
- power is affected by time (determines who is better)
- if we do the amount of work in less time we have more power output (work rate)
- work is proportional to energy transfer (if we do work at a higher rate with higher power output, we have a higher rate of energy transfer)
- energy = the ability to do work (stored work)
First Law of Thermodynamics
- energy cannot be created or destroyed, but only transforms from one form to another without being depleted (an expression of the conversion of energy principle)
- the body does not produce, consume or use up energy; instead it, transforms energy from one state into another as physiologic systems undergo continual change
What are the 3 Forms of Biological Work in Humans?
chemical, mechanical and transport
Chemical
biosynthesis of cellular molecules (go from one molecular form to another some work has to be done)
- when you from simple to complex molecule it requires a transfer of energy
- glycogen (a chain of glucose molecules put together) - every time we add glucose molecule to the chain we are doing chemical work and transferring energy
Mechanical
muscle contraction (creating force to contract our muscles - shortening our muscle against the weight, running, jumping etc.)
- generate ATP causing muscle to contract and those muscles pull on the bone which allow us to measure force and displacement and then calculate work
Transport
transfer of substances among cells (from one place to another)
- if something is moving down a concentration gradient we say nothing is happening or work is not being done but if it moving against its pressure gradient work is being done (requires ATP)
- for example pumping sodium and potassium against their concentration gradient that requires ATP is a type of work
Biosynthesis (Chemical Work)
bound energy in one substance that directly transfers to other substances to increase their potential energy
- protein synthesis (taking amino acids we eat and combining them together to make proteins that is going to require a transfer of energy and work)
- glycogen synthesis (if we take glucose that we broken down from our food and combine it to make glycogen that requires chemical work)
- ATP synthesis (energy currency in our body - how we can be do work by breaking down ATP - how do we take energy stored in food and then put them in energy which is ATP
What are the 2 Energy-Releasing and Energy-Conserving Processes?
exergonic (catabolic) and endergonic (anabolic)
Exergonic (Catabolic)
reactions that release energy
- any physical or chemical process that releases energy to surrounding (“downhill” processes) with free energy decline
- catabolic are things that breakdown more complex molecules in simple molecules and going to release energy that can do work
Endergonic (Anabolic)
reactions that require an input of energy (ATP)
- chemical reactions that store or absorb energy (“uphill processes) with free energy increase for biologic work
- taking simple molecule and putting them together to make complex molecule (protein) is going to be endergonic
Interconversions of Energy
transfer of potential energy always proceeds in a direction that decreases capacity to perform work
second law of thermodynamics
- tendency of potential energy to degrade to kinetic energy of motion with a lower capacity for work
- energy transfer is always inefficient (cannot take given amount of energy and put that exact same energy somewhere else) - anytime there is a chemical reaction energy in lost to heat, sound etc.
- anytime there is mechanical work not all the energy will go where we want to go (have transferred energy from muscle to ground but lost some due to heat (big one for energy transfer in people), sound)
- the biggest source of energy loss is heat
- net increase in randomness and disorder with every reaction which means we are not 100% efficient
- all potential energy in a system degrades to the unusable form of kinetic or heat energy
- total energy in a system remains constant; a decrease in one energy form matches the equivalent energy increase in another form
Inefficient Energy Transfer
chemical → mechanical
- heat is the biggest lose of energy (using ATP and we are inefficient at transferring energy so we create some heat)
- higher work rate (or power output) and higher rate that energy is being transferred leads us to be more inefficient and create more heat (as work rate increases we are going to have energy leak to places we do not want it to go and one of those is heat so we get hotter)
chemical → chemical
- take one molecule and changing it to another molecule will be inefficient
- increase in energy transfer associated with eating food (take complex molecules (proteins, fats, complex carbohydrates) and break them down into simple acid (fatty, amino) and sugars and bind them again in molecules that we can store (transfer of energy through these processes and every time it is inefficient there is a increase in heat production when there are chemical reactions in eating food)
