Lecture on Fatigue, Energy Metabolism, and Calorimetry

A set of vocabulary flashcards covering key concepts related to fatigue, energy metabolism, and calorimetry from the lecture notes.

Central Fatigue

Fatigue that originates in the brain and nervous system, reducing the neural signal to muscles.

Peripheral Fatigue

Fatigue that occurs in the muscles due to neuromuscular junction, energy depletion, byproduct buildup, and impaired calcium handling.

Maximal Voluntary Contraction (MVC)

The maximal voluntary force produced by the central nervous system and muscles.

Superimposed Twitch (SIT)

A brief muscle contraction triggered by electrical stimulation during a voluntary contraction.

Resting Twitch

An involuntary muscle flicker that happens in a relaxed state; smaller after fatigue.

Group III/IV Afferent Neurons

Sensory neurons conveying pain- and fatigue-related signals to the brain.

Total Energy Expenditure

The total amount of calories burned in a day, including resting metabolic rate, physical activity, and thermic effect of eating.

ATP (Adenosine Triphosphate)

The primary energy currency of the body; produces 7.3 kcal energy/mol when broken down. Resynthesized through cellular respiration, broken down through hydrolysis

Substrate-Level Phosphorylation

ATP generation independent of oxygen.

Oxidative Phosphorylation

ATP production that requires oxygen.

Direct Calorimetry

A method that measures heat production; high accuracy but costly and complex.

Indirect Calorimetry

A method that measures O2 consumption and CO2 production; versatile and non-invasive.

What are the stored and mobilized forms of carbohydrate

All carbs are eventually converted to glucose, at rest carbs are stored in the liver and muscles in the form of glycogen-> converted back to glucose as needed in muscle contractions.

What are the stored and mobilized forms of fat?

FFA is the only form of fat that could be used by the mitochondria. Fat is also stored as triglycerides, which is where a FFA originates from.

Respiratory Exchange Ratio (RER). RER of carbs and fat

The ratio of carbon dioxide produced / oxygen consumed; indicates the type of fuel utilized. =1 carbs is fuel, =0.71 fat is fuel, In between is a mix of both

Aerobic Glycolysis

The process of breaking down glucose with oxygen involved; occurs in the mitochondria.

Anaerobic Glycolysis

The process of breaking down glucose without oxygen, using glycolytic enzymes

Tricarboxylic Acid Cycle (TCA)

A metabolic pathway that oxidizes acetyl-CoA to produce ATP, NADH, and FADH2.

Beta Oxidation

The metabolic process of breaking down fatty acids to generate Acetyl-CoA.

Diacylglycerol (DAG) and ceramides

A lipid intermediate associated with lipotoxicity and metabolic dysfunction.  Excess FFAs → activation to fatty acyl-CoA → DAG accumulation

Fatty Acid Mobilization

The process of releasing fatty acids from adipose tissue; influenced by energy balance.