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Ch. 41 - Animal Nutrition
Chapter 41, Problem 7

If you were to jog 1 km a few hours after lunch, which stored fuel would you probably tap? a. muscle proteins b. muscle and liver glycogen c. fat in the liver d. fat in adipose tissue

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1
Understand the types of stored fuels in the body: Muscle proteins, muscle and liver glycogen, liver fat, and fat in adipose tissue are all potential energy sources.
Consider the timing of the exercise: A few hours after eating, your body has likely processed the meal and begun storing excess energy.
Identify the most readily available energy source: Muscle and liver glycogen are quick sources of energy that the body can use for sudden physical activities like jogging.
Rule out less likely sources: Muscle proteins are typically used as a last resort, and fat from the liver or adipose tissue is generally utilized during prolonged, low-intensity exercise.
Conclude the most probable source: Given the scenario (jogging a short distance a few hours after eating), the body would most likely use muscle and liver glycogen as the primary source of energy.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Glycogen Storage

Glycogen is a polysaccharide that serves as a form of energy storage in animals, primarily found in the liver and muscles. After a meal, glycogen stores are replenished with glucose derived from digested carbohydrates. During moderate exercise, such as jogging, the body preferentially utilizes glycogen as a quick source of energy, especially when the activity occurs a few hours post-meal.
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Carbohydrate Functions

Fat Metabolism

Fat metabolism involves the breakdown of stored fats (triglycerides) into fatty acids and glycerol, which can be used for energy. While fat is a significant energy source during prolonged, low-intensity exercise, it is less readily available than glycogen for quick bursts of activity. The body typically shifts to fat utilization after glycogen stores are depleted or during extended periods of exercise.
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Energy Utilization During Exercise

The body utilizes different energy sources based on the intensity and duration of exercise. For short to moderate activities, such as jogging shortly after eating, glycogen is the primary fuel source due to its rapid availability. As exercise continues or becomes more intense, the body may begin to tap into fat stores, but this transition takes longer and is less efficient for immediate energy needs.
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