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electrically charged particles created when electrolytes separate in a solution; may be positively or negatively charged


negatively charged electrolytes; include chloride, phosphorus, & bicarbonate


Positively charged electrolytes; include sodium, postassium, calcium, & magnesium


positive & negative ions balance each other out, achieving a neutral electrical charge

Major extracellular electrolytes

Sodium, Chloride, Calcium, Bicarbonate


helps nerve cells & muscle cells interact


maintains osmotic pressure & helps gastric mucosal cells produce hydrochloric acid


stabilizes cell membrane, reducing its permeability; transmits nerve impulses; contracts muscles; coagulates blood; & forms bones & teeth


regulates acid-base balance

Major intracellular electrolytes

Potassium, Phosphate, Magnesium


regulates cell excitability, nerve impulse conduction, resting membrane potential, muscle contraction, myocardial membrane responsiveness, & intracellular osmolality


controls energy metabolism


influences enzyme reactions, neuromuscular contractions, normal functioning of nervous & cardiovascular system, protein synthesis, & sodium & potassium ion transportation

Influences on electrolyte balance

Normal cell function
Fluid intake & output
Acid-base balance
Hormone secretion


regulate sodium & potassium balance (excrete potassium in exchange forsodium retention)

Lungs & liver

regulate sodium & water balance & blood pressure


secretes ANP, causing sodium excretion

Sweat glands

excrete sodium, potassium, chloride, & water in sweat

GI tract

absorbs & excretes fluids & electrolytes

Parathyroid glands

secrete parathyroid hormone, which draws calcium into the blood & helps move phosphorous to the kidneys for excretion

Thyroid gland

secretes calcitonin, which prevents calcium release from the bone

Hypothalamus & posterior pituitary

produce & secrete antidiuretic hormone causing water retention, which affects solute concentration

Adrenal glands

secrete aldosterone, whic influnces sodium & potassium balance in the kidneys

The effects of diuretics

Treat hypertension, heart failure, electrolyte imbalances, & kidney disease
Increase urine production

Insensible fluid losses

Ex: through the skin (affected by humidity & body surface area) & lungs (affected by respiratory rate and depth)

Sensible fluid losses

Ex: from urination, defecation, & wounds

Intracellular fluid

fluid inside the cell; must be balanced with extracellular fluid

Extracellular fluid

fluid outside the cell; must be balanced with intracellular fluid

Transcellula fluid

in the cerebrospinal column, pleural cavity, lymph system, joints, & eyes; remains relatively constant

Fluid types



equally concentrated with other solutions


less concentrated than other solutions


More concentrated than other solutions


form of passive transport that moves solutes from an area of higher concentration to an aea of lower concentration

Active transport

uses ATP to move solutes from an area of low concentration to an area of higher concentration


passive movement of fluid across a membrane from an area of lower solute concentration to an are of higher solute concentration

Capillary filtration

movement of fluid through capillary walls through hydrostatic pressure


secreted by the adrenal cortex regulates sodium & water reabsorption by the kidneys


also known as vasopressin---produced by the hypothalamus to reduce diuresis & increase water retention if serum osmolality increases or blood volume decreases

Renin-angiotensin-aldosterone system

If blood flow decreases, the juxtaglomerular cells in the kidneys secrete renin, which leads to the production of angiotensin II, a powerful vasoconstrictor


This hormone, produced & stored in the atria of the heart, stops the action of the renin-angiotensin-aldosterone system; decreases blood pressure by causing vasodilation & reduces fluid volume by increasing excretion of sodium & water


Regulated by the hypothalamus--Stimulated by an increase in ECF & drying of the mucous membranes--Causes a person to drink fluids, which are absorbed by the intestines, moved to th bloodstream, & distributed between the compartments


molecules that can give hydrogen molecules to other molecules; include solutions with a pH below 7


molecules that can accept hydrogen molecules; include solutions with a pH above 7


calculation based on the percentage of hydrogen ions & the amount of acids & bases in a solution

Normal blood pH

7.35-7.45, which represents the balance between hydrogen ions & bicarbonate ions


blood pH is below 7.35 & either the hydrogen ion concentration has increased or the bicarbonate level has decreased


blood pH is above 7.45 & either the hydrogen ion concentration has decreased or the bicarbonate level has increased

3 systems regulate acids & bases

Chemical buffers
Respiratory system

Chemical buffers

neutralize the offending acid or base

Respiratory system

regulates retention & excretion of acids


excrete or retain acids or bases

Chemical buffer systems

Bicarbonate buffer system
Phosphate buffer system
Protein buffer system

Bicarbonate buffer system

buffers blood & interstitial fluid

Phosphate buffer system

reacts with acids & bases to form compounds that alter pH; especially effective in renal tubules

Protein buffer system

acts inside & outside the cell; binds with acids & bases to neutralize them

Respiratory system

Functions as the 2nd line of defense
Responds to pH changes in minutes
Makes temporary adjustments to pH
Regulates CO2 levels in the blood


Make long-term adjustments to pH
Reabsorb acids & bases or excrete them into urine
Produce bicarbonate to replenish lost supply
Regulate bicarbonate production

Anion gap

Represents the level of unmeasured anions in extracellular fluid--Normally ranges from 8-14 mEq/L--Helps differentiate acidotic conditions

Signs & Symptoms of mild fluid loss

Orthostatic hypotension--Restlessness--Anxiety--Weight loss--Increased heart rate

Signs & Symptoms of moderate fluid loss

Confusion--Dizziness--Irritability--Extreme Thirst--Nausea--Cool, clammy skin--Rapid pulse--Decreased urine output

Signs & Symptoms of severe fluid loss

Decreased cardiac output--Unconsciousness--Marked tachycardia--Hypotension--Weak or absent periphera pulses--Cool, mottled skin--Decreased urine output

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