Integrated Exercise Physiology Lecture

Vocabulary flashcards summarizing key terms and definitions from the integrated physiology lecture covering nervous, endocrine, cardiovascular, respiratory, muscular, and metabolic responses to exercise.

Motor Cortex

Brain region that initiates voluntary muscle contractions by sending signals through spinal motor neurons.

Feed-forward Neural Control

Anticipatory signals from the brain that prepare cardiorespiratory and endocrine systems before movement begins.

Feedback Neural Control

Sensory information sent from muscles and organs back to the brain to adjust ongoing exercise responses.

Autonomic Nervous System (ANS)

Involuntary nervous system comprising sympathetic and parasympathetic branches that regulates heart rate, blood pressure, and organ function.

Sympathetic Nervous System

"Fight-or-flight" branch of the ANS that elevates heart rate, blood pressure, and metabolic rate during exercise.

Parasympathetic Nervous System

"Rest-and-digest" branch of the ANS that slows heart rate and promotes recovery; activity is withdrawn during exercise.

Epinephrine (Adrenaline)

Catecholamine hormone that raises heart rate, blood pressure, and mobilizes glucose and fatty acids for energy.

Norepinephrine

Catecholamine that works with epinephrine to increase cardiovascular function and fuel mobilization during exercise.

Cortisol

Glucocorticoid hormone that promotes breakdown of carbohydrate and fat, especially during prolonged exercise.

Growth Hormone

Anterior pituitary hormone that stimulates tissue growth and repair, elevated by resistance training.

Insulin Sensitivity

The body’s responsiveness to insulin; improves with regular exercise, enhancing glucose uptake.

Testosterone

Anabolic hormone that supports muscle growth and adaptation, rising after high-intensity resistance training.

Cardiorespiratory System

Heart, blood vessels, and lungs working together to deliver oxygen and remove carbon dioxide during exercise.

Oxygen Delivery

Transport of O₂ from lungs to working muscles via blood flow; increases with exercise intensity.

Carbon Dioxide Removal

Elimination of CO₂ produced by metabolism through ventilation and blood transport to the lungs.

Vasodilation

Widening of blood vessels that increases blood flow to active tissues.

Vasoconstriction

Narrowing of blood vessels that reduces blood flow to non-essential areas during exercise.

Respiratory Rate

Number of breaths per minute; rises to enhance gas exchange during exercise.

Homeostasis

Maintenance of internal stability; achieved during exercise by coordinated nervous, endocrine, and cardiorespiratory actions.

Buffering

Physiological process that neutralizes excess H⁺ ions to control pH during intense exercise.

Bicarbonate Buffer System

Primary blood buffer that converts H⁺ and CO₂ into carbonic acid and water, then exhaled as CO₂.

Lactate

By-product of anaerobic glycolysis that accumulates when ATP demand exceeds oxygen delivery.

Lactate Threshold

Exercise intensity at which lactate production exceeds clearance, causing rapid rise in blood lactate.

Respiratory Compensation

Increase in ventilation that removes CO₂ to counteract acidosis during high-intensity exercise.

PCO₂

Partial pressure of carbon dioxide in blood; decreases when ventilation increases during buffering.

Sweating

Evaporative cooling mechanism that removes heat and leads to fluid loss during exercise.

Dehydration

State of fluid deficit that impairs temperature regulation and performance.

Respiratory Water Loss

Water vapor lost via exhaled air; increases with breathing rate during exercise.

Muscle Recruitment

Activation of motor units to produce force; more recruitment raises metabolic demand.

ATP Turnover

Rate of ATP utilization and resynthesis; escalates with muscle recruitment and exercise intensity.

Vasodilation in Muscle

Local widening of arterioles supplying active fibers to match oxygen and nutrient needs.

Lactate Production

Formation of lactate when anaerobic glycolysis predominates during high-intensity work.

Fatigability

Decline in muscle force due to resource depletion and metabolite accumulation.

Size Principle

Ordered motor-unit recruitment from smallest (Type I) to largest (Type IIx) as force demand increases.

Type I Fiber

Slow-twitch fiber with high fatigue resistance, relying mainly on aerobic metabolism.

Type IIa Fiber

Fast oxidative fiber with moderate fatigue resistance, using both aerobic and anaerobic energy.

Type IIx Fiber

Fast glycolytic fiber with low fatigue resistance, specialized for explosive, anaerobic power.

Rate Coding

Adjustment of motor-neuron firing frequency to modulate muscle force output.

Phosphagen System (ATP-PC)

Immediate energy pathway that uses phosphocreatine to resynthesize ATP during short bursts.

Anaerobic Glycolysis

Energy pathway that breaks down glucose without oxygen, producing ATP and lactate.

Oxidative System

Aerobic pathway generating ATP via carbohydrate and fat oxidation, producing CO₂, H₂O, and heat.

Respiratory Exchange Ratio (RER)

VCO₂ / VO₂; indicates relative fuel use—lower values equal more fat, higher values more carbohydrate.

Excess Post-Exercise Oxygen Consumption (EPOC)

Elevated oxygen uptake after exercise used to restore homeostasis and clear metabolites.

VO₂ max

Maximum oxygen uptake; key indicator of cardiorespiratory fitness and endurance capacity.

Delayed Onset Muscle Soreness (DOMS)

Muscle pain 12–48 h after unaccustomed exercise caused by micro-tears and inflammation.

Resting Membrane Potential

Electrical charge difference (≈ -70 mV) across a cell membrane at rest.

Depolarization

Na⁺ influx that makes the inside of a cell less negative, initiating an action potential.

Repolarization

K⁺ efflux returning membrane potential toward resting levels following depolarization.

Hyperpolarization

Excessive K⁺ outflow making membrane potential more negative than resting level.

Sodium-Potassium Pump

Active transport mechanism maintaining ion gradients and resting membrane potential.

Pituitary Gland

Endocrine master gland releasing growth hormone, ACTH, TSH, and ADH.

Adrenal Medulla

Inner adrenal region producing epinephrine and norepinephrine during stress or exercise.

Adrenal Cortex

Outer adrenal region secreting cortisol and aldosterone for metabolism and fluid balance.

Pancreas

Gland releasing insulin to lower and glucagon to raise blood glucose.

Thyroid Hormones (T₃ & T₄)

Hormones that elevate metabolic rate and support cardiovascular function.

Erythropoietin (EPO)

Kidney hormone that stimulates red blood cell production to enhance oxygen transport.

Heart Chambers

Right/left atria and ventricles that pump deoxygenated and oxygenated blood.

Atrioventricular (AV) Valves

Tricuspid and mitral valves preventing backflow from ventricles to atria.

Semilunar Valves

Pulmonary and aortic valves preventing backflow into ventricles after ejection.

Myocardium

Cardiac muscle layer; thickest in left ventricle to generate systemic pressure.

Intercalated Discs

Specialized connections allowing synchronized contraction of cardiac cells (syncytium).

Sinoatrial (SA) Node

Heart’s natural pacemaker generating spontaneous action potentials.

Atrioventricular (AV) Node

Delays impulse to allow atrial contraction before ventricular depolarization.

Purkinje Fibers

Conduct impulses rapidly through ventricles for coordinated contraction.

Stroke Volume (SV)

Blood volume ejected by one ventricle per heartbeat.

Cardiac Output (Q)

Heart rate × stroke volume; total blood pumped per minute.

Ejection Fraction (EF)

Percentage of end-diastolic volume ejected each beat (SV/EDV).

Frank-Starling Mechanism

Greater ventricular filling stretches fibers, increasing contraction force and SV.

Vasoconstriction

SNS-induced vessel narrowing that elevates peripheral resistance and blood pressure.

Muscle Pump

Rhythmic skeletal-muscle contractions that aid venous return during movement.

Respiratory Pump

Pressure changes during breathing that assist venous return to the heart.

Hematocrit

Percentage of blood volume occupied by red blood cells.

Pulmonary Ventilation

Movement of air into and out of lungs; sum of tidal volume × breathing rate.

Pulmonary Diffusion

Exchange of O₂ and CO₂ between alveoli and pulmonary capillary blood.

Capillary Diffusion

Gas exchange between systemic capillary blood and active tissues.

Dalton’s Law

Total gas pressure equals sum of partial pressures of each constituent gas.

Henry’s Law

Amount of gas dissolved in a liquid is proportional to its partial pressure and solubility.

Alveoli

Tiny lung sacs providing large surface area for gas exchange.

Surfactant

Substance secreted by type II alveolar cells lowering surface tension to keep alveoli open.

Oxyhemoglobin Dissociation Curve

Graph showing relationship between PO₂ and hemoglobin saturation with O₂.

Bohr Effect

Rightward shift of O₂-Hb curve caused by ↑ CO₂, ↓ pH, and ↑ temperature, enhancing O₂ unloading.

Myoglobin

Muscle-cell protein that stores and transports O₂ from sarcoplasm to mitochondria.

Arterio-Venous O₂ Difference (a-vO₂ diff)

Difference in O₂ content between arterial and venous blood; reflects tissue O₂ extraction.

Chemoreceptors

Sensors detecting changes in blood CO₂, O₂, and pH to adjust ventilation.

Ventilatory Threshold (VT)

Point during incremental exercise where ventilation rises disproportionately to VO₂, indicating lactate accumulation.

V̇E/VO₂

Ventilatory equivalent for oxygen; liters of air breathed per liter of O₂ consumed.

V̇E/VCO₂

Ventilatory equivalent for carbon dioxide; reflects efficiency of CO₂ clearance.

Valsalva Maneuver

Forced exhalation against a closed glottis, increasing intrathoracic pressure during heavy lifts.

Cardiovascular Drift

Gradual HR rise and SV fall during prolonged steady exercise, often due to dehydration and heat.

Plasma Volume

Liquid component of blood; decreases with sweating and increases with endurance training.

Hemoconcentration

Increase in blood cell ratio caused by plasma loss, elevating hematocrit and viscosity.

Hypervolemia

Expanded plasma volume due to training or fluid loading, enhancing thermoregulation and SV.

Central Command

Brain-derived neural drive initiating simultaneous motor and autonomic responses at exercise onset.

Functional Sympatholysis

Local inhibition of SNS vasoconstriction in active muscles to ensure adequate blood flow.

Tidal Volume

Volume of air inhaled or exhaled per breath.

Minute Ventilation (V̇E)

Total volume of air breathed per minute; tidal volume × frequency.

Respiratory Compensation Point (RCP)

Intensity where hyperventilation occurs to offset metabolic acidosis (VT2).

Bicarbonate Loading

Ingestion of sodium bicarbonate to enhance extracellular buffering capacity and performance.

Phosphate Buffers

Intracellular buffers that accept H⁺, helping maintain pH during high-intensity exercise.

Protein Buffers

Amino-acid side chains within cells and plasma that bind H⁺ to stabilize pH.