Block 1 material

What is bioenergetics?

The study of biological energy conversion from foodstuffs to usable energy (ATP)

T/F: There is an abundance of ATP in the body at any given moment?

False. There is only about a few seconds’ worth of ATP at any time.

Does all of our food get turned into usable energy? If yes, why? If no, where does it go? How can we measure how efficient our conversion rate is?

No, most of energy is lost in conversion as heat (maintains core temp of 37 C)

• Efficiency of conservation = (usable energy, ATP)/(total energy conserved)

How can polysaccharides be absorbed?

Must be broken down into smaller pieces → disaccharides → monosaccharides

• Only monosaccharides can be absorbed @ the small intestine

What are digestible carbohydrates? What is an example of this?

Digestible carbohydrates are carbs that we have enzymes in our bodies to break them down

e.g. starches (potato, pasta, wheat, rice, etc.)

What are indigestible carbohydrates? What is an example of this?

Digestible carbohydrates are carbs that we do NOT have enzymes in our bodies to break them down

e.g. fiber (fruits, veggies, nuts, grains, etc)

How are triglycerides related to bioenergetics?

They are used for energy storage

• Acyl groups (fatty acid chains) are broken down to be metabolized (connected to glycerol via ester linkages)

How is creatine phosphate related to bioenergetics?

It serves as an important phosphate storage for donating inorganic phosphates to ADP → ATP synthesis

• also nitrogen ‘n’ protein yum

What is ATP composed of?

Nucleobase (adenine) + ribose sugar + three phosphate groups

Where is all of the energy in ATP? What might the levels of ATP, ADP, and AMP signal to the body?

The energy is stored in the phosphorus!

• High levels of ATP indicate that you are probably not very metabolically active at that moment in time

• High levels of AMP indicate that you are probably very metabolically active

Describe the coupling of exergonic and endergonic reactions. List some examples

Exergonic reactions liberate energy from bonds which are then used to fuel endergonic reactions

• Na+/K+ ATPase

What is the Q10 Effect?

The physiological phenomenon that describes that for every 10 C increase in temperature, the reaction rate will double'

• This is why it is so important to warm up for maximum power and the best metabolic rate! (‘cause muscles sit at a lower temperature than our body’s core)

What are the three main energy systems? Where do they occur in the cell? And how many ATP do they yield?

1. Creatine phosphate system (occurs in the cytoplasm; 95% in skeletal muscle; 1 ATP)

2. Glycolytic pathway (aka glycolysis) (occurs in the cytoplasm; 2 ATP)

3. Aerobic respiration (occurs in the mitochondria; 32 ATP)

Which energy system is the fastest in regard to ATP production? How long does this system last?

Creatine phosphate; 6-8 seconds

T/F: ADP can donate a phosphate group to another ADP

True; this will produce yield AMP

Describe the glycolytic pathway

The second energy pathway to be recruited during high-intensity activity; lasts a few minutes; only metabolizes carbohydrates

Describe aerobic metabolism

(krebs cycle, electron transport chain aghhh); all substrates can be metabolized to produce ATP

• slowest system of ATP production, but the most efficient

• 99% of metabolism is performed via aerobic metabolism only if O2 is available

T/F: The energy systems are not mutually exclusive

True; aerobic is 99% of metabolism during everyday activities or low-impact exercise, but the other two dominate during high intensity exercise

What is the conceptual definition of metabolism?

Sum of all energy converting/exchanging reactions in the body

What is the functional definition of metabolism?

Rate of heat production by the body in kcal/minute

What is direct calorimetry? Do we use it in exercise physiology?

Measuring the production of body heat directly (and CO2 and O2 production); no, because it only measures resting metabolism

• Not reliable for exercise physio because the ergonometers often produce confounding heat and heat is often stored in the body to raise core temps during exercise ; also ignores aerobic contribution

What is indirect calorimetry? Do we use it in exercise physiology?

Measuring metabolism based on O₂ consumption (based on the assumption that O₂ is proportional to heat released)

• Measures O₂ consumption

• Yes because it is able to measure metabolism at rest and at activity ; also ignores aerobic contribution

How can we measure the volume of oxygen consumed?

Two ways:

• VO₂ = VO_{2, in} - VO_{2, out}

• VO₂ = V_i(O₂%) - V_e(O₂%)

How can we measure the volume of carbon dioxide produced?

• VCO₂ = V_e(CO₂%) - V_i(CO₂%)

  • The amount of CO2 consumed is usually negligible, so we can usually say V_e(CO₂%) = VCO₂

**How much oxygen do we intake per minute at rest?

300 mL of O₂ consumed/min

What are the two types of indirect calorimetry? What are the differences?

1. Open circuit (room air inhaled; measures both O₂ and CO₂)

2. Closed circuit (sealed chamber with variable percentages of O2; measures O2): often used to simulate high-altitude conditions

What is RQ? Do we use this in exercise physio?

Respiratory Quotient

• Ratio of CO2 produced to O2 consumed at the cellular level — depends on the fuel metabolized

• No, because it only addresses this ratio at the cellular level

What is the RQ for carbohydrates and for lipids?

Carbs: 1.0

Lipids: 0.71

What is RER? Do we use this in exercise psio?

Same ratio of CO2/O2 as RQ, but on the whole-body scale

• uses the assumption that CO2 expiration must be proportional to the CO2 production of all cells

• Allows for assumption of what fuel is being metabolized most

  • Protein is impossible to account for here, but that’s okay because protein is not often used as a fuel source anywho (except for starvation or extreme fatigue)