Fluid, Electrolytes, and Acid-Base

acid

Any substance capable of releasing hydrogen ions in solution

active transport

Movement of substances across a cell membrane against an electrochemical gradient

anions

Negatively charged ions

ascites

Accumulation of serous fluid in the peritoneum

baroreceptors

Stretch receptors located in major arteries and veins that monitor vascular volume

base (or alkali)

Any substance that can combine with and decrease hydrogen ions in solution; alkali

buffers

Compounds that help stabilize the pH of a solution by neutralizing added acid or base

cations

Positively charged ions

diffusion

Movement of molecules from an area of higher concentration to one of lower concentration

electrolytes

Chemical compounds that dissociate into ions when in solution; usually refers to extracellular sodium, potassium, and chloride

extracellular fluid

Body fluid outside the cells; mainly interstitial fluid and plasma

filtration

Passage of a solution through a semipermeable membrane from a region of higher pressure to a region of lower pressure

hyperosmolar

One compartment contains a greater concentration of a dissolved substance (hyperosmolar) than the other compartment (hypoosmolar)

hypertonic

Of greater concentration than in body fluids

hypoosmolar

One compartment contains a lesser concentration of a dissolved substance (hypoosmolar) than the other compartment (hyperosmolar)

hypotonic

Of lower concentration than in body fluids

interstitial fluid

Fluid between the cells

intracellular fluid

Portion of body fluid contained within the cells

intravascular fluid

Fluid inside the blood and lymphatic vessels

ions

Charged particles formed by the dissociation of electrolytes in a solution

milliequivalent

Unit used to give the concentration of an electrolyte in solution; commonly expressed as mEq/L

osmolality

Concentration of solutes in a solution, expressed as milliosmols per kilogram

osmolarity

Concentration of solutes in a solution expressed as milliosmols per liter

osmosis

Movement of a fluid through a semipermeable membrane from a region of lower to higher solute concentration

osmotic pressure

Pressure exerted by nondiffusible particles in a solution across a semipermeable membrane; tends to hold fluid within its container and is opposed by hydrostatic pressure

tonicity

Fluid's effect on cell size