Concepts of F&E

Electrolytes

a substance that ionizes on dissolving in solution; that is, some of its molecules split or dissociate into electrically charged atoms or ions.

• Atom

• Molecule

• Ion

ELECTROLYTES: Properties and Components

Atom

 The smallest part of an element still has the element’s properties

Molecule

• Two or more atoms combine to form a substance

Ion

• An atom carries an electrical charge because it has gained or lost electrons

Cation

An ion that has given away or lost electrons, therefore carries a positive charge.

Anion

An ion that has gained electrons, therefore carries a negative charge.

Liters

Mililiters

measure volumes of fluids

mEq

combining activity of an electrolyte

• Intracellular

• Extracellular

Body Fluid Compartments

Intravascular

Compartment: Fluid inside the blood vessel

Intracellular

Compartment: Fluid inside the cell

Extracellular

Compartment: Fluid outside the cell

Third-spacing

Due to disease or injury, the accumulation and sequestration of trapped extracellular fluid in an actual or potential body space.

• The trapped fluid represents a volume loss and is unavailable for normal physiological processes.

Third-spacing

is when fluid leaves the normal blood vessels and becomes trapped in body spaces or tissues, so the body cannot use it normally.

Edema

An excess accumulation of fluid in the interstitial space; occurs as a result of alterations in oncotic pressure, hydrostatic pressure, capillary permeability, and lymphatic obstruction.

Body Fluid

________ transport nutrients to the cells and carry waste products from the cells.

Water

Dissolved Substances

Constituents of body fluids:

• Consists of ______ and _______. The largest single fluid constituent of the body is

Diffusion

• The process whereby a solute (a substance that is dissolved) may spread through a solution or solvent (solution in which the solute is dissolved).

• a solute spreads the molecules from an area of higher concentration to an area of lower concentration.

Osmosis

The movement of solvent molecules across a membrane in response to a concentration gradient, usually from a solution of lower to one of higher solute concentration.

Osmotic Pressure

•  is the force that draws the solvent from a less concentrated solute through a selectively permeable membrane into a more concentrated solute, thus tending to equalize the concentration of the solvent.

Filtration

• The movement of solutes and solvents by hydrostatic pressure. The movement is from an area of higher pressure to an area of lower pressure. 

Hydrostatic Pressure

• The force exerted by the weight of a solution. When a difference exists in the ________ on two sides of a membrane, water, and diffusible solutes move out of the solution that has the higher hydrostatic pressure by the process of filtration. 

• The pushing force of fluid against the walls of a blood vessel or membrane.

Osmolality

Miliosmoles

Refers to the number of osmotically active particles per kilogram of water; it is the concentration of a solution. In the body, osmotic pressure is measured in ________(mOsm).

Cell membrane

Capillary walls

________ and _______ separate body compartments. Cell membranes are selectively permeable; that is, the cell membrane and the capillary wall allow water and some solutes free passage through them.

Isotonic Solutions

• When the solutions on both sides of a selectively permeable membrane have established equilibrium or are equal in concentrations, they are isotonic. Isotonic to human cells; thus very little osmosis occurs. _________ have the same osmolality as body fluids.

Hypotonic Solutions

• When a solution contains a lower concentration of salt or solute than another, more concentrated solution, it is considered _______. Has less salt or more water than an isotonic solution; these solutions have lower osmolality than body fluids. 

Hypertonic Solutions

•  A solution that has a higher concentration of solutes than another, less concentrated solution is ________; these solutions have a higher osmolality than body fluids. 

Osmotic Pressure

is determined by the concentration of solutes in the solution.

Active Transport

• If an ion is to move through a membrane from an area of lower concentration to an area of higher concentration, an __________ is necessary. An ________ moves molecules or ions against concentration and osmotic pressure. 

• Ingested liquids

• Water in food

• Water formed by oxidation of foods

Water enters the body through three sources:

• 10 mL of water

• About ________ is released by the metabolism of each 100 calories of fat, carbohydrates, or proteins. 

Kidney

• The ______ play a major role in regulating fluid and electrolyte balance and excrete the largest quantity of fluid. Normal ______ can adjust the amount of water and electrolytes leaving the body. 

Homeostasis

 is a term that indicates the relative stability of the internal environment. The concentration and composition of body fluids must be nearly constant.