Cellular Energy Production

Questions and Answers

What is the primary function of the aerobic system?

To store energy in the form of glycogen

To produce ATP directly for muscle contraction

To break down protein for energy

To produce ATP from other energy sources in the body (correct)

Which process occurs in the mitochondria?

Protein synthesis

The Krebs cycle and the electron transfer system (correct)

Anaerobic glycolysis

Aerobic lipolysis

What is the role of vitamins in the human energy systems?

To store energy in the form of glycogen

To produce ATP directly

To break down protein for energy

To release energy from cell sources (correct)

What is the difference between aerobic power and aerobic capacity?

Aerobic power is for high-intensity exercise, while aerobic capacity is for low-intensity exercise Signup and view all the answers

What is the largest component of total daily energy expenditure (TDEE)?

Basal energy expenditure Signup and view all the answers

What is the result of anabolic processes?

The building-up of tissues and molecules Signup and view all the answers

What is the primary source of energy during rest?

Fat Signup and view all the answers

What is the function of water in the human energy systems?

To help in hydrolysis reactions Signup and view all the answers

What are the two fundamental processes of metabolism?

Anabolism and catabolism Signup and view all the answers

What is the approximate percentage of REE derived from fat on a mixed diet?

60% Signup and view all the answers

What is the primary source of energy during high-intensity exercise lasting 0-4 seconds?

ATP and creatine phosphate Signup and view all the answers

What is the approximate percentage of muscle mass in an adult male?

45% Signup and view all the answers

What is the primary difference between muscle fibers?

Their ability to produce energy Signup and view all the answers

What is the approximate REE of an adult?

1 C/kg/h Signup and view all the answers

What is the primary source of energy during low-intensity exercise lasting several hours?

Adipose lipids Signup and view all the answers

What is the effect of a diet rich in carbohydrates on REE?

It increases the REE derived from carbohydrates Signup and view all the answers

What is the term for the energy requirements of the many different cellular and tissue processes necessary to maintain physiological activities in a resting, post absorptive state?

Basal Metabolic Rate (BMR) Signup and view all the answers

What is the effect of eating a meal on the metabolic rate?

It increases the metabolic rate due to dietary induced thermogenesis (DIT) Signup and view all the answers

What is the percentage of Resting Energy Expenditure (REE) derived from carbohydrates on a mixed diet?

40% Signup and view all the answers

Which of the following factors affects the magnitude of the thermic effect of food (TEF)?

Type of food ingested Signup and view all the answers

What is the effect of nicotine in cigarettes on Resting Energy Expenditure (REE)?

It increases REE Signup and view all the answers

What is the effect of altitude exposure on Resting Energy Expenditure (REE)?

It increases REE Signup and view all the answers

What is the percentage increase in Resting Energy Expenditure (REE) due to alcohol intake?

15% Signup and view all the answers

What is the effect of losing body weight on Resting Energy Expenditure (REE)?

It decreases REE Signup and view all the answers

During which type of exercise does the ATP-PCr system predominate?

Short powerful muscular activities Signup and view all the answers

What is the primary source of energy during moderate exercise (approximately 50% VO2 max)?

Blood glucose and fat Signup and view all the answers

As exercise intensity increases, what is the primary source of energy?

Muscle glycogen Signup and view all the answers

What is the term for the transition from using fat to using carbohydrates during increased exercise intensity?

Cross-over concept Signup and view all the answers

What is the primary source of energy during events of long duration?

Fat Signup and view all the answers

What is overreaching in the context of exercise?

Physical and mental stress that may impair physical performance Signup and view all the answers

What is a common myth in exercise training?

Training in the fat-burning zone is effective for weight loss Signup and view all the answers

What is chronic fatigue in the context of exercise?

A common condition in endurance athletes Signup and view all the answers

What is a common characteristic of people who are more likely to experience overtraining?

Females between 40-50 years old Signup and view all the answers

What is a primary factor in peripheral fatigue during exercise?

Depletion of ATP stores in the muscles Signup and view all the answers

What is a mechanism of central fatigue during exercise?

High levels of serotonin in the brain Signup and view all the answers

What is a benefit of proper training in delaying the onset of fatigue?

Improved tolerance of stress Signup and view all the answers

What is a role of calcium in muscle contraction related to fatigue?

Interfering with optimal energy metabolism Signup and view all the answers

What is a treatment approach for overtraining syndrome?

Behavioral therapy and graded exercise Signup and view all the answers

Study Notes

Energy Systems

ATP cannot be used directly as a source of energy for muscle contraction, but it produces ATP in large quantities from other energy sources in the body.
The processes occur through the Krebs cycle and the electron transfer system in the mitochondria.
The aerobic system produces ATP at a lower rate, but with a larger production of energy in the form of ATP in the presence of adequate oxygen levels.

Human Energy Systems

Human energy systems can be classified as anaerobic or aerobic and subdivided into energy systems for power and capacity.
Anaerobic power: ATP-PCr energy system.
Anaerobic capacity: lactic acid energy system.
Aerobic power: aerobic glycolysis.
Aerobic capacity: aerobic lipolysis.

Nutrients for Energy Systems

Water, vitamins, and minerals function closely with protein in the structure and function of many enzymes.
Water helps in hydrolysis.
Vitamins are needed for energy to be released from cell sources.
Minerals are essential for cellular energy processes.

Metabolism

Metabolism represents the sum total of all physical and chemical changes that take place within the body.
Two fundamental processes: anabolism (building-up process that needs energy) and catabolism (tearing-down process that creates energy to support anabolism).
Metabolic rate reflects how rapidly the body is using its energy stores.
Total daily energy expenditure (TDEE) is accounted for by three factors: basal energy expenditure, physical activity, and thermic effect of food.

Basal Energy Expenditure

Basal energy expenditure is the largest component of TDEE.
It increases due to eating a meal.
Physical activity is the most variable component.
Constant use of energy to build up and tear down substances within the cells.
Certain automatic body functions also consume energy.

Resting Metabolic Rate

Resting metabolic rate (RMR) = BMR + small amounts of additional energy expenditure associated with eating and previous muscular activity.
RMR is also known as REE (resting energy expenditure).

Effect of Eating on Metabolic Rate

Eating a meal increases the metabolic rate due to the dietary induced thermogenesis (DIT) or thermic effect of food (TEF).
TEF is the energy necessary to absorb, transport, store, and metabolize the food consumed.
It increases with the caloric content of the meal.
The type of food ingested may affect the magnitude of TEF.

Factors Affecting Resting Energy Expenditure

Genetic factors: changes in the proportion of muscle tissue and fat cause changes in REE.
Genetic factors affecting REE: age, sex, natural hormonal activity, body size, and surface, body composition to a certain extent.
REE declines through age.
REE of women is 10-15% lower than men.
Genetically lean individuals have a higher REE than stocky individuals.
Losing body weight lowers the daily REE.
Environmental factors: caffeine, nicotine, cold and hot weather, and altitude exposure increase REE.

Energy Sources Used During Rest

No need for ATP; the oxygen system is enough: CHO and fats can be used.
On a mixed diet, 40% of REE is derived from CHO and 60% from fat.
Increasing the percentage of CHO or fat in the diet increases the contribution of one of them to the REE.
After an overnight fast, the contribution of fat increases.

Muscle Influence on Energy Production

Rough estimate of REE: 1 C/kg/h.
Adult male: 45% muscles; adult female: 35% muscles.
The proportion varies depending on the level and type of physical activity.
Human body possesses several different types of muscle fibers, and their primary differences are in the ability to produce energy.

Muscle Fiber Types

All three systems – ATP-PCr, lactic acid, and O2 – are used in one way or another during most athletic activities.
ATP-PCr predominate in short powerful muscular activities (10 sec).
Lactic acid system predominate during longer and middle distance sprints (30-120 sec).
The O2 system possesses a lower rate of ATP production than the other two systems, but its capacity for total ATP production is much greater.
The O2 system can be improved through a physical conditioning program.

Energy Sources Used During Exercise

ATP-PCr system uses ATP and phosphocreatine.
Lactic acid system uses only CHO (+++ muscles gly stores).
O2 system uses CHO (muscle gly, liver gly, BG) and fat (muscles and AT TG) primarily, and prot also.
Determination of the energy source depends on intensity and duration.
For moderate exercise (app 50% VO2 max), BG and fat may provide much of the needed energy.
If > 50% VO2 max, the body begins to rely more on intramuscular stores of gly and TG.
As intensity continues to increase, the body relies more and more on CHO (muscle gly).
This transition from the use of fat to CHO during the increase of intensity is called the cross-over concept.

Fatigue

Chronic fatigue: +++ in endurance athletes, involves overreaching and overtraining, associated with disturbances of the immune system, infections, mental stress, and personality traits.
Acute fatigue: inability to continue exercising at a desired level of intensity, ATP production rates are unable to match ATP utilization rates.

Causes of Acute Fatigue

Mechanism not fully understood, depends on the type of exercise, state of fitness, and fiber-type composition of the muscle.
Peripheral fatigue: occurs when compounds to produce ATP are depleted, and by-products of metabolism accumulate in the muscle and interfere with optimal energy metabolism.
Central fatigue: occurs with substrate depletion and by-products accumulation (e.g., high levels of serotonin).

Delaying the Onset of Fatigue

Proper training: physiologically, psychologically, and biomechanically.
Proper nutrition with adequate supply of nutrients.

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Description

This quiz covers the processes of energy production in the body, including the role of mitochondria and the Electron Transfer System in generating ATP from different energy sources.