Exercise Physiology Exam 1

Physiology

The study of how the body functions.

Homeostasis

The body's ability to maintain a stable internal environment.

Exercise physiology

The study of how the body responds and adapts to physical activity.

Environmental physiology

The study of how environmental factors (e.g., temperature, altitude) affect body function.

Sport physiology

The study of physiological adaptations specifically related to athletic performance.

Acute adaptations

Adaptations that occur immediately during/after exercise (e.g., increased heart rate).

Chronic adaptations

Adaptations that develop over time with consistent training (e.g., increased muscle mass).

Cross-sectional research design

Studies that compare different groups at one point in time.

Longitudinal research design

Studies that follow the same group over time.

Independent variable

The variable that is manipulated (e.g., exercise intensity).

Dependent variable

The variable that is measured (e.g., heart rate response).

Muscle organization

The correct order is Muscle → Fascicle → Fiber → Myofibril.

Sarcomere

The basic unit of muscle contraction, consisting of overlapping actin and myosin.

Motor unit

A motor neuron and all the muscle fibers it innervates.

Sarcolemma

The specialized membrane surrounding a muscle fiber.

Sarcolemma role

Conducts action potentials.

T-tubules role

Transmit signals into the muscle fiber.

Sarcoplasmic reticulum role

Stores and releases calcium (Ca²⁺).

Acetylcholine (ACh)

The neurotransmitter responsible for triggering muscle contraction.

Calcium (Ca²⁺)

The ion that initiates muscle contraction by binding to troponin.

Role of ATP in muscle contraction

ATP is required to break the actin-myosin crossbridge and power the myosin head movement.

Muscle fiber types

Type I (slow-twitch): Fatigue-resistant, oxidative, used for endurance. Type IIa (fast-twitch): Moderately fatigue-resistant, glycolytic-oxidative, used for moderate-intensity efforts. Type IIx (fast-twitch): Fatigue quickly, glycolytic, used for short bursts of power.

Type I

Oxidative (aerobic)

Type IIa

Glycolytic (anaerobic)

Type IIx

ATP-PCr (phosphagen)

Carbohydrates storage

As glycogen in muscle fibers and the liver.

Fats storage

In adipose tissue and intramuscular fat droplets (mostly in type I fibers).

Primary function of proteins in metabolism

Mostly for building and repairing tissues; rarely used for energy.

Insulin

Helps store glucose as glycogen.

Glucagon

Helps break down glycogen into glucose during exercise.

GLUT4 and GLUT5

Proteins that help transport glucose into muscle cells.

Epinephrine and norepinephrine

They increase blood glucose levels and facilitate fat breakdown.

ATP generation necessity

It is not stored in large amounts.

Three energy systems

ATP-PCr System, Glycolytic System, Oxidative System.

ATP-PCr system usage

During short, high-intensity activities (~10 seconds).

Muscle fibers relying on ATP-PCr system

Type IIx (fast-twitch).

Primary fuel for glycolytic system

Glucose (from glycogen).

Glycolytic system usage

For moderate to high-intensity exercise lasting 30 seconds to 2 minutes.

Muscle fibers relying on glycolytic system

Type IIa and IIx.

Fuels used in oxidative system

Carbohydrates and fats.

Oxidative system usage

During low to moderate-intensity, long-duration exercise.

Muscle fibers relying on oxidative system

Type I (slow-twitch).

Electron transport chain ATP production

Electrons from NADH & FADH power membrane proteins that pump H⁺ ions, which flow back through ATP synthase, producing ATP.

Fat metabolism vs carbohydrate metabolism

Fat oxidation requires more oxygen and takes longer to produce ATP.

Lactate production in type II fibers

They rely on anaerobic glycolysis, which converts pyruvate into lactate when oxygen is limited.

Possible fates of lactate

Used for energy in type I fibers. Transported to the liver for gluconeogenesis (Cori cycle). Accumulates and contributes to fatigue.