Muscle Energy Metabolism Quiz

18 Questions

Which energy system in muscle cells replenishes ATP through oxidative phosphorylation?

Oxidative system (Aerobic system)

What is the result of removing 1 phosphate group from ATP?

ADP

During which type of exercise can ATP turnover increase 100-fold above rest?

Sprint exercise

What is the primary energy source used to power muscular activity during the initial phase of exercise?

ATP-PC system

What is the molecule formed by the removal of 2 phosphate groups from ATP?

$eta$-AMP

During intense exercise, where does most ATP come from?

Breakdown of phosphocreatine (PCr) and glycogen to lactate

What is the primary energy source for resting muscle?

Aerobic metabolism of fatty acids in the mitochondria

What does the respiratory quotient (RQ) of 0.75 at rest indicate?

The body burns approximately 85% fat and 15% carbohydrate

What is the final product of anaerobic glycolysis?

$Lactic$ $acid$

What are the primary fuels used in muscle metabolism?

$Fatty$ $acids$ and $ketone$ $bodies$

During low-intensity exercise, what is the primary energy source?

Circulating free fatty acids (FFAs) from adipocytes

What is the predominant fuel source during high-intensity activity?

Muscle glycogen

What is the main function of lactate in the liver during exercise?

Formation of glucose via gluconeogenesis

What contributes to muscle fatigue during exercise?

Build up of lactate and lowering of pH

What is the purpose of the Cori cycle during exercise recovery?

Recycling of lactic acid by the liver

During high-intensity activity, which of the following is the most important source of fuel for muscle?

Muscle glycogen

What is the primary role of liver glycogen during medium-intensity activity?

Regulating blood glucose levels

Which process contributes to the production of glucose from non-glucose sources during exercise?

Gluconeogenesis

Study Notes

The ATP-PC system is a rapid energy reserve system, using creatine phosphate (CP) to rapidly regenerate ATP for muscle contraction
ATP is the active energy molecule in the body, and CP is its storage molecule in resting muscle
The ATP-PC system uses the creatine kinase reaction to maintain ATP concentrations, providing energy for a few seconds
The synthesis of ATP and CP in the mitochondria are closely coupled
During intense exercise, most ATP is derived from the breakdown of phosphocreatine (PCr) and glycogen to lactate
Lactic acid is the final product of anaerobic glycolysis, which favors lactate production in low oxygen conditions
Lactate accumulates in muscle during intense exercise, causing a drop in pH and diffusing into the bloodstream
Muscle metabolism primarily uses glucose, glycogen, fatty acids, and ketone bodies as fuels
The muscle relies on aerobic metabolism of fatty acids in the mitochondria as the primary energy source of the resting muscle, using fatty acids as fuel at rest
During prolonged exercise, the liver increases the release of glucose into the circulation, and adipose tissue increases the hydrolysis of triglycerides and release of FFAs
The extent of substrate contribution to ATP production depends on the intensity and duration of muscular activity
The respiratory quotient (RQ) or respiratory exchange ratio (RER) measures fuel selection by reflecting the substrate being oxidized for energy
At rest, the RER is 0.75, indicating the body burns approximately 85% fat and 15% carbohydrate
As exercise intensity increases, the RER also increases to reflect the shift towards carbohydrate oxidation.

Test your knowledge on how muscle fibers obtain energy for contractions through aerobic and anaerobic metabolism, including the role of ATP as an energy carrier and its functions in muscle contraction.

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