Macro #1: Energy Sources Flashcards
How does our body store energy?
ATP
How is glucose stored?
As Glycogen
How are fatty acids stored?
As triglycerides
How are amino acids stored?
As proteins
Unit to measure energy
Calorie or kcal (kilocalorie)
Kcal
- How energy expenditure is expressed
- Heat required to raise the temperature of 1 kg of water by 1 C
Calorimetry
The measure of energy through how much heat a nutrient produces (steak may have more energy then a cheerio and therefore produce more heat/energy)
2 types of calorimetry
- Direct calorimetry
- Indirect calorimetry
Direct Calorimetry
Measures heat transfer through bomb calorimetry and determining energy content of nutrients
Indirect Calorimetry
Measures gas through a metabolic chamber or cart. Measures O2 consumed and CO2 produced, and estimates energy expenditure
Bomb calorimetry
Determines energy content of nutrients by the amount of heat produced during combustion of the nutrient
How does bomb calorimetry work?
- Put food in the chamber and fill it with oxygen
- Water surrounds the chamber
- You light the chamber and combust it
- Measure the heat produced during combustion of the nutrient to determine energy
Metabolic Chamber
A method used for indirect calorimetry where people are in a lab and scientists can see exactly what they eat, how much O2 they consume and how much CO2 they expel
Metabolic Cart
Measures O2 and CO2 by putting a mask over someones face while they do things
Respiratory Exchange Ratio (RER)
CO2 Produced / O2 consumed
What is the average RER at rest
0.75
Energy Metabolism
Chemical reactions that enable cells to store and use energy from nutrients
Basic concept of energy metabolism
Substrate goes into an enzyme to create a product. That product becomes the new substrate that can go into a different enzyme and create a new product
Three substrates our bodies prefer to use
- Phosphocreatine (PCr)
- Carbohydrates (glucose)
- Fat (fatty acids)
Phosphocreatine (PCr)
Produces ATP quickly but only produces small quantities (sprinting)