Chapter 3: Metabolism and Energy Balance Flashcards
What are calories?
A calorie is the amount of energy that is needed to raise the temperature of 1 gram of water by 1 degree Celsius at a pressure of 1 atmosphere.
Calories are provided by macronutrients, micronutrients, vitamins, and minerals through our diet.
We technically write the calories we use as a kilocalorie. But the general population knows this simply as a calorie.
How do the calorie yields look for each of the nutritional sources we could take in?
Calorie amount based on the macronutrient
- Nutritional carbohydrates have a kilocalorie yield of 4 per gram.
- Nutritional protein has a kilocalorie yield of 4 per gram.
- Nutritional fats have a kilocalorie yield of 9 per gram.
- Stored fats from carbohydrate sources have a kilocalorie yield of 3.27 per gram.
- Alcohol has a kilocalorie yield of 7 per gram.
What is energy intake and energy expenditure? What are the many aspects that go into the calculation of energy expenditure?
Energy intake is the total calories taken in during a 24 hour period. The simple observations that can be made for a fitness and nutrition specialist is the gain or loss in lean muscle mass. If someone is gaining weight over time, they are consuming an excess of calories compared to their expended ones. And the opposite is true when someone is consuming too few calories. They will lose weight.
Energy expenditure is measured in multiple ways:
- RMR
- the thermic effect of food
- physical activity
- growth
These are occurring all of the time in the body.
What are the formulas used to calculate RMR?
RMR formulas:
Men = 66.4730 + (13.7516 x weight in kg) + (5.0033 x height in cm) – (6.7550 x age in years)
Women = 655.0955 + (9.5634 x weight in kg) + (1.8496 x height in cm) – (4.6756 x age in years)
We have two forms of energy balance that we are likely to be in. What are these two types? How does it look when we gain weight over time?
simply put, energy balance = calories in and calories out.
Creating an energy balance involves a lot more than simply managing your weight.
two forms of energy balance we can be in:
- a positive energy balance is one where more energy is being consumed than is being expended.
- negative energy balance is the opposite of that, where there is more energy being expended than is being consumed.
Even though that is true, research shows that people who gain weight in the long term actually have periods of plateaus that show up. So, the person will gain weight, and then plateau for some time period, and then go back to gaining weight. It only takes small changes to help stop the rate of weight gain.
What is the currency of cellular energy? What is cellular metabolism?
The currency of cellular energy is actually the molecule ATP, or adenosine triphosphate.
Cellular metabolism is a series of reactions where the goal is for the nutrients to reach the state of being ATP. Adenine is made up of adenine and ribose. This adenine is then attached to three phosphates and the two bonds between the three phosphates will store and release energy.
Give a thorough overview the three central energy systems that we use in our bodies.
The phosphagen system is the first system. This is the combination of phosphocreatine and the muscle’s stored ATP. The energy system is the first one that kicks in. it provides energy for the body in high-intensity situations and does not last as long as other systems.
As the muscle tissue continues to use phosphocreatine, it runs out, and the glycolysis systems kicks in. ATP is now made for the body using glucose. This starts around seven seconds into the run, and it is the second anaerobic process. Neither of the last two require the presence of oxygen.
The last energy system is the oxidative system which uses fats and oxygen to make energy for the body. This is the aerobic metabolism, and it is the primary fuel source during long activities.
What are the times each energy system is active as the primary fuel source?
The phosphagen system provides a near-instant source of energy and this lasts up to 30 seconds.
The aerobic glycolysis system kicks in at around 7 seconds and takes over as the main system after the 30 seconds of the phosphocreatine system. The system lasts 2- 3 minutes.
After the glycolysis we have the oxidative system taking over for the remainder of the time in cardio.
What are the inputs needed for the energy systems to work? What is the ATP production that we get from the various types of fuel?
When the fuel type is a ketones, we will be donating amino acids and 2 carbons, and we will have an end result in 22 ATP.
When the fuel type is glucose, we will donate 2 pyruvate and 6 carbons total, and this will result in 30 – 32 ATP.
When the fuel type is lactate, we will be donating a lactate and 6 carbons, and we will have an end result of 30 – 32 ATP.
When the fuel type is fatty acids, we will donate 1 palmitic acid and 16 carbons, and this will result in 106 ATP.
How many calories does the US Dept HHS declare is required for men and women?
Men: 2,000-3,000
Women: 1,600-2,400
Energy expenditure is a result of the cumulation of what processes?
RMR
thermic effect of food
physical activity
physical growth
What is the most influential of the 4 energy expenditure processes?
RMR, aka BMR (basal met. rate) as it consumes ⅔ of the body’s total energy expenditure in a 24hr period
Explain the process of converting ATP to ADP to energy.
ATP by itself does not provide cellular energy. The energy is stored within the bonds between the three phosphates in the ATP molecule, and those bonds need to be broken in the presence of water to release the energy.
The first step is to break down adenosine triphosphate into its simpler counterpart, adenosine diphosphate (ADP). That break requires an enzyme, which causes a chemical reaction to occur. In this case, the enzyme is ATPase, which breaks the bond between the second and third phosphates to release the stored energy. The phosphate-removal process, dephosphorylation, requires water (H20). This is one of the reasons why water makes up two-thirds of the body’s weight. Importantly, the breakdown of ATP to ADP releases one acidic proton (H+)
What are the primary sources of energy?
glucose
fatty acids
lactate
ketones
Define aerobic metabolism.
Describe the process of aerobic metabolism.
Aerobic metabolism produces ATP in presence of oxygen.
The process begins with acetyl coenzyme A (acetyl-CoA) after the pyruvate molecule enters the mitochondria.
This molecule is formed into fuel triggering the 1st stage of aerobic metabolism, the Krebs cycle.
The 2nd stage is the electron transport chain, which forms most of the ATP during aerobic metabolism.
The outputs of aerobic metabolism are ATP, CO2, and H2O
