Lecture Notes: Conservation of Mass, Hydration, Thermoregulation, and Exercise

A vocabulary-focused set of flashcards covering mass conservation, hydration status, fluid balance, thermoregulation, energy use in muscles, and related concepts.

Conservation of mass

Mass cannot be created or destroyed in a closed system; in physiology, balance of inputs (inflow) and outputs (outflow) maintains homeostasis.

Homeostasis

Stability of the internal environment despite external changes; challenged by exercise.

Feedback control

Regulation where the output is fed back to influence inputs to maintain a set point.

Feedforward control

Regulation that anticipates changes and adjusts variables before they occur.

Receptor-mediated control

Regulation triggered by sensors (receptors) detecting changes and signaling responses.

Inflow

Movement of fluids and electrolytes into the body.

Outflow

Loss of fluids and electrolytes from the body.

Euhydrated

Normal, adequately hydrated body water status.

Hypohydration

Dehydration; state of reduced body water content.

Hyperhydration

Overhydration; excess body water.

Inflow = Outflow

A balanced state where intake equals loss to maintain hydration.

Fecal fluid loss

Fluid loss via feces (about 5%).

Respiratory fluid loss

Fluid loss via the respiratory tract (about 10%).

Skin fluid loss

Fluid loss via the skin (about 50%), mainly through sweating.

Kidney fluid loss

Fluid loss via urine (about 35%).

Skeletal muscle contraction

Process of converting chemical energy to mechanical energy; efficiency varies by activity; excess energy becomes heat.

Thermoregulation

Regulation of body temperature to maintain core temperature.

Evaporation

Heat loss when liquid water becomes vapor, aided by heat from tissues.

Convection

Heat transfer by the movement of air or water.

Radiation

Heat transfer through radiant energy without a medium.

Conduction

Heat transfer through direct contact between objects.

Set-point for sweating

Skin temperature at which sweating begins to regulate heat loss.

Vasodilation

Widening of blood vessels to increase blood flow and heat loss.

Vasoconstriction

Narrowing of blood vessels to reduce blood flow and conserve heat.

Osmolality

Concentration of solutes in body fluids; drives water movement between compartments.

Hypotonic beverage

A drink with lower osmolality than plasma, absorbed more quickly.