Lecture September 10: Sweat, Heat Transfer, and Acid-Base Balance

Vocabulary flashcards focusing on heat transfer concepts and the physiochemical approach to acid-base balance (SID, Atot, CO2) from the lecture notes.

Sweat

Body fluid secreted by sweat glands; enables evaporative cooling as the sweat evaporates, creating a heat loss gradient from the body to the outside.

Evaporation

Heat loss process where liquid (sweat) becomes vapor, removing heat from the body.

Conduction

Heat transfer through direct contact; more effective when combined with convection.

Convection

Heat transfer via moving air or fluid; enhances overall heat exchange with the environment.

Vasodilation

Widening of blood vessels (especially skin), increasing skin blood flow and heat transfer to the skin.

Feedforward (respiration)

Anticipatory increase in breathing to meet metabolic demand before measurable changes in oxygen or carbon dioxide occur.

pH

Negative logarithm of hydrogen ion concentration; small changes alter protein charge and structure, affecting function.

H⁺ (hydrogen ion)

The proton whose concentration determines pH; higher H⁺ lowers pH and can alter molecular charge.

HCO₃⁻ (bicarbonate)

Weak base that buffers hydrogen ions in the acid-base system.

Strong Ion Difference (SID)

Net electrical charge of fully dissociated strong ions (e.g., Na⁺, K⁺, Cl⁻, lactate⁻); SID changes drive pH; SID is near zero in sarcoplasm and about +40 mEq/L in plasma.

Atot (Total Weak Acids)

Total concentration of weak acids (proteins like albumin and phosphates Pi) that buffer by accepting or donating H⁺.

CO₂ / PCO₂

Carbon dioxide partial pressure; respiratory component of acid-base balance controlled by breathing; higher PCO₂ increases acidity.

Lactate

Lactate ion produced from pyruvate during glycolysis, especially in high-intensity exercise; contributes to acidosis.

Pyruvate

End product of glycolysis; can be converted to lactate under anaerobic conditions.

Glycolysis

Metabolic pathway converting glycogen/glucose to pyruvate; under anaerobic conditions, pyruvate is reduced to lactate.

Phosphocreatine (PCr)

High-energy phosphate reserve that donates phosphate to ADP to rapidly regenerate ATP during short, intense efforts.