Chapter 4 - Exercise Metabolism and Bioenergetics

Question 1

Define metabolism.

Answer 1

All of the chemical reactions that occur in the body to maintain itself. Metabolism is the process in which nutrients are acquired, transported, used, and disposed of by the body.

Question 2

Define exercise metabolism.

Answer 2

The examination of bioenergetics as it relates to the unique physiologic changes and demands placed on the body during exercise.

Question 3

Define substrates.

Answer 3

The material or substance on which an enzyme acts. Dietary food broken down into smaller by-products. Examples: Proteins, carbohydrates, and lipids (fats) constitute the main substrates used to transfer metabolic energy to be used for all types of cellular activity and life.

Question 4

Define carbohydrates.

Answer 4

Organic compounds of carbon, hydrogen, and oxygen, which include starches, cellulose, and sugars, and are an important source of energy. All carbohydrates are eventually broken down in the body to glucose, a simple sugar.

Question 5

Define glucose.

Answer 5

A simple sugar manufactured by the body from carbohydrates, fat, an to a lesser extent protein, which serves as the body’s main source of fuel.

Question 6

Define glycogen.

Answer 6

The complex carbohydrate molecule used to store carbohydrates in the liver and muscle cells. When carbohydrate energy is needed, glycogen is converted into glucose for use by the muscle cells. A string of glucose molecules that can rapidly be broken down into glucose and used for energy during periods of prolonged or intense exercise.

Question 7

Define fat.

Answer 7

One of the three main classes of foods and a source of energy in the body. Fats help the body use some vitamins and keep the skin healthy. They also serve as energy stores for the body. In food, there are two types of fats, saturated and unsaturated.

Question 8

Define triglycerides.

Answer 8

The chemical or substrate form in which most fat exists in food as well as in the body. Triglycerides are derived from fats eaten in foods or made from other energy sources such as carbohydrates.

Question 9

Define protein.

Answer 9

Amino acids linked by peptide bonds, which consist of carbon, hydrogen, nitrogen, oxygen, and usually sulfur, and that have several essential biologic compounds. Rarely supplies much energy during hte exercise and in many descriptions is ignored as a significant source of fuel for energy metabolism. When protein becomes a significant source of fuel is starvation.

Question 10

Define gluconeogenesis.

Answer 10

The formation of glucose from noncarbohydrate sources, such as amino acids (proteins). During negative energy balance (ie. low-calorie diet), amino acids are used to assist with energy production (usually during starvation).

Question 11

Define adenosine triphosphate (ATP).

Answer 11

A high-energy compound/molecule that stores energy (to be used in cellular and mechanical work including exercise) and is a transfer unit within the cells of the body.
Example: energy released to perform cellular work like a muscle contraction
-only about 40% of the energy released from ATP is actually used for cellular work, the remainder is heat.

Question 12

Define adenosine diphosphate (ADP).

Answer 12

A high-energy compound occurring in all cells from which adenosine triphosphate (ATP) is formed.

Question 13

What are the three metabolic ways that cells can generate ATP?

Answer 13

1. The ATP-PC System
2. The glycolytic system (glycolysis)
3. The oxidative system (oxidative phosphorylation)

Question 14

What is glycolysis?

Describe the difference between aerobic glycolysis vs anaerobic glycolysis.

Answer 14

-Glycolysis is an anaerobic means of producing ATP through a chemical breakdown of glucose.
-Anaerobic glycolysis provides energy for.30-50 seconds duration of intense work - typically 8-12 repetitions
-Glucose/Glycogen must be converted to glucose-6-phosphate before glycolysis can occur.
Converting glucose to glucose-6-phosphate uses 1 ATP molecule.
Convert glycogen to glucose-6-phosphate does not.
End Result:
Glucose or Glycogen is broken down into Pyruvic Acid (aerobic glycolysis) or Lactic Acid (anaerobic glycolysis)
-2 ATP for each unit of glucose and 3 ATP from each unit of glycogen

Question 15

What is the oxidative system (oxidative phosphorylation)?

Answer 15

-The process of using substrates with the aid of oxygen to generate ATP
-The most complex of the energy systems for generating ATP

Question 16

What are the 3 oxidative/aerobic systems? Describe each process.

Answer 16

1. Aerobic Glycosis - use of O2 to form Pyruvic Acid
2. The Krebs Cycle - Pyruvic Acid converted into Acetyl Coenzyme A (Acetyl CoA) and oxidized to produce 2 units of ATP and by-products CO2 and hydrogen, hydrogen then is combined with other enzymes
3. The electron transport chain (ETC) - first two processes then provide energy for the oxidative phosphorylation of ADP to form ATP

Question 17

Define beta oxidation.

Answer 17

The breakdown of triglycerides (fats) into smaller subunits called free fatty acids (FFAs) to convert FFAs into acyl-CoA molecules, which then are available to enter the Krebs cycle and ultimately lead to the production of additional ATP.
-Beta oxidation requires more oxygen to produce ATP

Question 18

Define excess postexercise oxygen consumption (EPOC).

Answer 18

The state in which the body’s metabolism is elevated after exercise.

Question 19

What is the respiratory quotient (RQ)?

Answer 19

-The amount of carbon dioxide expired divided by the amount of oxygen consumed, measured during rest or at a steady state of exercise using a metabolic analyzer.
-Can be used to estimate fuel contribution during exercise (fats vs carbs)

Question 20

What is the ATP-PC System?

Answer 20

-The process of creating a new ATP molecule from a phosphocreatine molecule.
-The simplest and fastest energy system and occurs without the presence of oxygen (anaerobic).
-Provides energy for primarily high-intensity, short-duration bouts of exercise or activity.
-Lasts approximately 5-10 seconds duration
-Activated at the onset of energy, regardless of intensity, bc of its ability to produce energy very rapidly in comparison with the other systems.

Question 21

Define bioenergetics.

Answer 21

The study of energy how energy is transformed in the human body through various biochemical reactions.