Exercise Physiology and Bioenergetics Review

A comprehensive set of vocabulary flashcards covering skeletal muscle physiology, bioenergetics, the nervous system, and endocrine regulation based on lecture review notes.

Actin

The thin filaments found in skeletal muscle structure.

Myosin

The thick filaments found in skeletal muscle structure which contain cross bridges.

Tropomyosin

A protein on actin that binds and blocks the binding site from myosin cross bridges.

Troponin

A protein on actin that binds with calcium, changing shape to pull tropomyosin away from the binding site.

Sarcoplasmic reticulum

The structure within muscle cells where calcium is stored and released.

Type I muscle fibers

Slow-twitch, oxidative fibers characterized by low force production, high myoglobin content, high mitochondrial density, and high capillary density.

Type II muscle fibers

Fast-twitch, anaerobic fibers characterized by high force production and rapid fatigue, relying on the phosphagen and glycolytic systems.

ATPase

The enzyme associated with the myosin heavy chain that breaks down ATP to determine the speed of muscle contraction.

Size Principle

The order of motor unit recruitment starting with Type I, followed by Type IIa, and finally Type IIx.

Creatine kinase

The enzyme that catalyzes the reaction between ADP and phosphocreatine to create ATP and free creatine in the phosphagen system.

Phosphofructokinase (PFK)

The rate-limiting enzyme for glycolysis that is regulated by the relative concentrations of ATP to ADP and NAD to NADH.

Cytosol

The location in the cell where the phosphagen system and glycolysis take place.

Mitochondria

The cellular location where the Krebs cycle, electron transport chain, and beta oxidation take place.

Lactate fates

After production, this substance can go to the liver to make glucose, to Type I muscle tissue for the Krebs cycle, or to the heart.

Phosphagen system

The energy system used predominantly for short bursts of activity lasting less than $10$ seconds, such as a $100$ meter dash.

Anaerobic glycolysis

The energy system used predominantly for activities lasting about $2$ minutes, such as an $800$ meter dash.

Aerobic system

The energy system used predominantly for activities lasting a mile or longer, such as a marathon.

Tricarboxylic acid cycle

Another name for the Krebs cycle or the citric acid cycle.

Krebs cycle yield

Produces $3$ NADH and $1$ FADH2 per round of the cycle.

NADH ATP yield

Produces $3$ ATP in the electron transport chain.

FADH2 ATP yield

Produces $2$ ATP in the electron transport chain.

Beta oxidation

The process of converting fatty acids into acetyl CoA in the mitochondria.

Golgi tendon organs (GTOs)

Sensory neurons in the muscular tendon junction that activate inhibitory interneurons to reduce force production and prevent muscle tearing.

Afferent

Sensory neurons that conduct signals towards the central nervous system.

Efferent

Motor neurons that conduct signals away from the central nervous system.

Acetylcholine

The neurotransmitter used to cause muscle contractions.

Sodium-potassium pump

The system responsible for maintaining the resting membrane potential of a neuron.

Glucagon

A hormone secreted by the pancreas when blood glucose is low to stimulate glycogenolysis and gluconeogenesis in the liver.

Insulin

A hormone secreted by the pancreas when blood glucose is high that signals GLUT4 to facilitate glucose entry into cells.

Steroid hormones

Lipid-soluble hormones that pass through the cell membrane to interact directly with receptors and DNA.

Non-steroid hormones

Protein or peptide-based hormones that cannot pass through the cell membrane and must utilize a second messenger system.

Antidiuretic hormone (ADH)

A hormone that causes water retention in the kidneys.

Aldosterone

A hormone from the adrenal gland that tells the kidneys to reabsorb sodium, causing water to follow through osmosis.

Erythropoietin (EPO)

A hormone produced by the kidneys that stimulates red blood cell production in the bone marrow.

Respiratory Exchange Ratio (RER)

A ratio where a value of $1.0$ indicates 100% carbohydrate burning and $0.707$ indicates 100% fat burning.

Resting metabolic rate (RMR)

The energy required for the body at rest, typically between $1200$ and $2400$ calories per day.

Total daily energy expenditure (TDEE)

The average daily energy requirement inclusive of activity, typically between $1800$ and $3000$ calories per day.

Isotopes for energy expenditure

Specific elements used for study including carbon $13$, deuterium ($H^2$), and oxygen $18$.