Chapter 4 Flashcards
bioenergetics
The study of energy in the human body.
metabolism
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.
exercise metabolism
The examination of bioenergetics as it relates to the unique physiologic changes and
demands placed on the body during exercise.
substrates
The material or substance on which an enzyme acts.
carbohydrates
—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
glucose
A simple sugar manufactured by the body from carbohydrates, fat, and to a lesser extent protein; it serves
as the body’s main source of fuel.
glycogen
The complex carbohydrate molecule used to store carbohydrates in the liver and muscle cells. When
energy is needed, glycogen is converted into glucose for use by the muscle cells.
fat
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.
tryglycerides
The chemical, or substrate, form in which most fats exist in food as well as in the body
protein
Amino acids linked by peptide bonds which consist of carbon, hydrogen, nitrogen, oxygen, and usually
sulfur, and that have several essential biologic compounds
gluconeogenesis
The formation of glucose from non-carbohydrate sources such as amino acids
Adenosine tri-phosphate ATP
Energy storage and transfer unit within the cells of the body
Adenosine Diphosphate
—A high-energy compound occurring in all cells from which ATP is formed.
β-oxidation
The breakdown of triglycerides 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.
excess post-exercise oxygen consumption EPOC
The state in which the body’s metabolism is elevated after
exercise.
lack of carbohydrates in the diet cause
cause fatigue, poor mental function, and lack of endurance and stamina
Th e primary end product aft er the digestion of carbohydrates is the
formation of
glucose
how does glucose enter the cells
with insulin
where is glycogen stored?
liver and muscle cells
For one cycle on a cross bridge for muscle contraction ___ ATP is needed
2
Only about ___% of the energy released from ATP is actually used for
cellular work, like muscle contraction. Th e remainder is released as heat
40
When the enzyme ATPase combines with an ATP molecule, it splits the last phosphate
group away, releasing a large amount of free energy, approximately ____ kcal per unit of
ATP
7.3
ATP equation
ATP ⇔ ADP Pi energy release
what are the 3 metabolic pathways in which cells can generate ATP?
- Th e ATP-PC system
- Th e glycolytic system (glycolysis)
- Th e oxidative system (oxidative phosphorylation)
PC or CP
phosphocreatine
ATP-PC System
ATP needs to be replenished by transferring phosphate from phosphocreatine to an ADP molecule, enough energy is produced to create one cross-bridge cycle, this is the simplest and fastest of the energy systems, anaerobic, for high intensity short durations such as power and strength training, this system is activated at the onset of activity regardless of activity because it is so rapid
glycolysis
anaerobic means to produce ATP glucose or glycogen must be converted to glucose 6 phosphate glucose uses 1 ATP in this process glycogen doesn’t, produces 2ATP for glucose and 3 ATP for glycogen, produces more energy than ATP-PC system , limited to about 30-50 seconds, (usually workouts with rep ranges of 8-12)
Oxidative System
energy system that uses substrates with the aid of oxygen to generate ATP (aerobic)
3 oxidative / aerobic systems
- Aerobic glycolysis
- Th e Krebs cycle
- Th e electron transport chain (ETC)
anaerobic glycolysis produces
lactic acid
aerobic glycolysis produces
pyruvic acid, and eventually converted to Acetyl COa then used in the Krebs cycle to produce 2 units of ATP
Why are Carbohydrates the preferred substrate for the oxidative production of ATP?
fat oxidation produces
far more ATP per molecule of fat compared with a molecule of carbohydrate, fat oxidation requires more oxygen to produce ATP; thus carbohydrates are the preferred fuel
substrate for the oxidative production of ATP
Th e end results of the aerobic metabolism of carbohydrates and fats are
water and carbon dioxide
Which takes longer? the aerobic breakdown of glucose and fat, the anaerobic metabolism of glucose, or the ATP-PC cycle?
Th e
aerobic breakdown of glucose and fat takes much longer than the anaerobic metabolism of glucose and far longer than the ATP-PC cycle.
Energy is used to form the ________ that facilitate muscle contraction.
myosin actin cross bridges
intensity and duration of exercise
are ____ related.
inversely
As the duration of exercise increases (up to approximately
2 minutes), the primary source of energy comes from __________ but some energy comes from the other pathways as well.
anaerobic metabolism of glucose
(anaerobic glycolysis),
bioenergetics of exercise can be indirectly measured in
(e.g., treadmill, cycle ergometer, rowing ergometer, cross-country ski
simulator, swimming fl ume) while measuring the concentrations of oxygen and carbon
dioxide and volume of expired air.
steady-state exercise
, is exercise performed at a constant pace (intensity). For example, steady-state exercise could be described as walking at a brisk pace of 4 mph or 15:00 minutes per mile for a total of 15 minutes or 1 mile.
Th e body prefers _______ because carbon dioxide and
water are more easily eliminated
aerobic or oxidative metabolism
respiratory Quotient RQ
is the amount of carbon dioxide (CO 2 ) expired divided by the amount of oxygen (O 2 ) consumed, measured during rest or at steady state of exercise using a metabolic analyzer
RQ in steady state of exercise indications
During steady-state exercise, an RQ of 1.0
indicates that carbohydrate is supplying 100% of the fuel, whereas an RQ of 0.7 indicates that fat is supplying 100% of the fuel for metabolism. Any RQ between 0.7 and
1.0 indicates a mixture of carbohydrates and fats are fueling metabolism.
