Presentation on theme: "Energy Production. The body extracts energy from stored reserves to accomplish tasks requiring energy: 1. basic maintenance and repair, e.g. circulation,"— Presentation transcript:
The body extracts energy from stored reserves to accomplish tasks requiring energy: 1. basic maintenance and repair, e.g. circulation, respiration, ion gradients, synthesis, etc. 2. digestion/absorption 3. physical activity
Adenosine Triphosphate All energy must eventually be in the form of ATP in order for it to be used for cell metabolism. ATP is the energy "currency" of the cell. Why?
ATP is the only source of energy that the body can use. Stored energy (e.g. fat, glycogen, creatine phosphate) must first be converted to ATP before the body can actually use it. Laundromat Analogy: The work that must be done (the laundry) can only be paid for (fueled by) quarters. So, you go to the laundromat with 5,000 loads of laundry. In your pocket you have a roll of quarters. You realize that this will not be enough money, but since the quarters are heavy you only bring one roll. You also bring a handful of $1 bills and a $100 bill because your wallet was so full of singles you couldn’t fit it in your back pocket. Just in case you don’t have enough cash, you also bring your Visa Checkcard with you. However, there is an overdraft penalty on your Visa Checkcard, so if the money is not replaced very quickly you must pay for your overdraft.
LaundromatHuman Systems QuartersCreatine Phosphate, ATP $1Glycogen, Blood Glucose $100Stored Fat Visa CheckcardProtein
Quarters = ATP Immediate energy source (ATP/CP) Hydrolysis reaction takes place without oxygen. The amount of ATP/CP stored is very limited. Provides energy for 8-12 seconds of intense exercise. Body pool of ATP "turns over" 5000 times/day! ATP ADP + Pi + energy PCr + ADP ATP + creatine
$1 = glycogen/glucose Glycogen/glucose is like having dollar bills that can be broken down to quarters in a change machine. Much greater capacity ($1) than carrying quarters. The human body stores ~350 g of glycogen, not enough to sustain long duration of exercise or a period of time without food.
Non-oxidative metabolism: requires no O 2 and results in lactate accumulation (like dimes and nickels that the liver can turn lactate back into glucose). Oxidative metabolism: requires O 2.The amount of ATP produced from the breakdown of a molecule of glucose is ~ ATP.
$100 = Stored Fat Fat stores are the energy sources for rest and prolonged activity at lower levels of exertion. Breaking down fat is a SLOW process. Just as getting change for the $100 bill may be take a while, mobilizing fat stores to be used to meet cellular energy demands also takes longer than using glucose, ATP, or PCr.
The amount of ATP generated from a single molecule of palmitate (a common fatty acid) is ~ ATP. Fat can only be oxidized in the presence of oxygen.
VISA = Protein When either carbohydrate intake or overall energy intake is low; proteolysis (the breakdown of protein – mostly from lean muscle) provides energy for biologic work. VISA: using protein as energy supplements the ATP/PCr, glycogen and fatty acids that provide the majoroty of the ATP.
Amino acids, which combine to form proteins, consist of a carbon backbone and an amine group. If the amine group is removed (deamination) the resulting molecule may enter into the energy producing pathways Additionally, amino acids can be converted IN THE LIVER to alanine and then to glucose in a process called gluconeogenesis.
CHO has ~4kcal/g Glycogen is stored with grams of water per gram of glycogen so it is only about 30% useable energy So the stored CHO actually only has about 1.4 kcal per gram or about 600 kcal/pound
Fat is about 90% triglyceride and 10% water. TG contains 9 kcal/g * 90% = about 8 kcal/g for stored fat or about 3500 kcal/pound So energy stored as CHO (glycogen) is 6 times as heavy as energy stored as FAT. If humans were to store energy as glycogen instead of fat we would be forced to carry at least 100 extra pounds just to have the same amount of energy available.
Protein CHO Fat PyruvateAmino Acids Fatty Acids Acetyl-CoA Krebs Cycle and ETC ATP produced