Energy Flashcards
What is the energ metabolism equation?
EnergyIn - EnergyOut = EnergyStored
Where does energy go? (Percentages)
50% inefficiency
5-10% their mic effect of food
20-40% Na+/K+ pumps
20-40% synthesis/life
What will bomb calorimeters do for us?
It will tell us how much energy is in the food we eat.
What are some ways to measure body composition and what are they?
Skin fold - use a caliper to gauge the thickness of various folds of skin.
Hydrodensitometry - weigh the person first on land and then in water. Uses volume and body density to determine percentage of body fat.
Biochemical impedance - uses a current through the body to determine body fat percentage because leaner the person the less resistance there will be to the current.
Air displacement plethysmography - commonly called the “bod pod”. There are sensors that determine the body fat percentage through computerized sensors that determine the amount of air displaced by the person’s body.
DEXA - uses X-rays.
Waist circumference
CT
MRI
Total Potassium
Total body water (deuterium)
What is a direct calorimeter used for?
It measures heat loss from the body. The issue is that heat is stored in the body for a long time so there is a slow response time. Therefore, subjects live in the direct calorimeter, which is a closer room, for like 24 hours.
What is Indirect calorimetry and what is it used for?
You can determine the individual components of energy expenditure such as CO2/ O2/ urea/heat.
What is the respiratory quotient?
Ratio of CO2 produced by a fuel to O2 used to burn that fuel.
Volume of CO2 produced / Volume of O2 used.
- it basically uses the amount ot O2 consumed and CO2 produced in order to tell us which fuel she was using. For instance, if the person oxidized proteins, it will have a have a different ratio than if the patient was oxidizing carbs or fat.
What is doubly labeled water?
Basically, you give someone this radiolabeled water with heavy Oxygen and Hydrogen. Of course, Hydrogen can only leave the body through sweat, urine etc. But, Oxygen can leave the body in those ways too as well as through CO2 production. Therefore, you measure the percentage left of each of the Hydrogen and Oxygen and the difference between the two is the amount oxygen lost due to metabolism.
WHat parts of RMR are not fixed?
Diet, exercise, temperature, hormones, stress, lean body mass, drugs
What is NEAT?
Non-exercise activity thermogenesis
Orexigenic? Anorexigenic?
Orexigenic - increased food intake
Anorexigenic - decreased food intake
What are some orexigenic signals? Anorexigenic signals?
O - ghrelin
A - stomach stretching, CCK, GLP-1, insulin, leptin
What part of the brain is responsible for feeding not signals?
Hypothalamus - arcuate nucleus specifically
What is leptin? What mice studies were done?
Leptin is a molecule that essentially tells your body that you are full and to stop eating. In mice studies, there were Ob/Ob mice which became fat because they did not have Leptin. If given Leptin they’d be fine. On the other hand, there were Db/Db mice that had resistant receptors so even if they had Leptin they would still over eat. Obesity is similar to the Db mice in that the Leptin receptors begin to become resistant.
What good does A fecal transplant do?
- You have two skinny germ free mice. You give one a fecal translate from a lean mouse and they stay lean. You give The other a fecal transplant from an obese mouse and they become obese.
- being lean is dominant over obese though so if you put a germ free mouse in a cage with both obese and lean mice then it will eat both of their feces and be lean.
- obese mice housed with lean mice became leaner.
