Chapter 1.3-1.5 (Body Fluid Compartments, Homeostasis, General Characteristics of Homeostatic Systems) Key and Clinical Terms (Vander's Human Physiology)

Extracellular Fluid

Any fluid inside the body and outside the cell

Internal Envirronment

Extracellular fluid (interstitial fluid and plasma)

Interstitial Fluid

Extracellular fluid surrounding tissue cells; excludes plasma

Interstitium

Interstitial space; fluid-filled space between tissue cells

Intracellular Fluid

Fluid in cells; cytosol plus fluid in cell organelles, including nucleus

Plasma

Liquid portion of blood; component of extracellular fluid

Dynamic Constancy

A way of describing homeostasis that includes the idea that a variable such as blood glucose may vary in the short term but is stable and predictable when averaged over the long term

Homeostasis

Relatively stable condition of internal environment that results from regulatory system actions

Equilibrium

No net change occurs in a system; requires no energy

Feedforward Regulation

Aspect of some control systems that allows system to anticipate changes in a regulated variable

Homeostatic Control Systems

Collections of interconnected components that keep a physical or chemical variable of internal environment within predetermined normal ranges of values

Negative Feedback

Characteristic of control systems in which system’s response opposes the original change in the system

Positive Feedback

Characteristic of control systems in which an initial disturbance sets off train of events that increases the disturbance even further

Set Point

Steady-state value maintained by homeostatic control system

Steady State

No net change; continual energy input to system is required, however, to prevent net change