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62 terms

Fluid & Electrolytes Made Easy

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Ions
electrically charged particles created when electrolytes separate in a solution; may be positively or negatively charged
Anions
negatively charged electrolytes; include chloride, phosphorus, & bicarbonate
Cations
Positively charged electrolytes; include sodium, postassium, calcium, & magnesium
Electroneutrality
positive & negative ions balance each other out, achieving a neutral electrical charge
Major extracellular electrolytes
Sodium, Chloride, Calcium, Bicarbonate
Sodium
helps nerve cells & muscle cells interact
Chloride
maintains osmotic pressure & helps gastric mucosal cells produce hydrochloric acid
Calcium
stabilizes cell membrane, reducing its permeability; transmits nerve impulses; contracts muscles; coagulates blood; & forms bones & teeth
Bicarbonate
regulates acid-base balance
Major intracellular electrolytes
Potassium, Phosphate, Magnesium
Potassium
regulates cell excitability, nerve impulse conduction, resting membrane potential, muscle contraction, myocardial membrane responsiveness, & intracellular osmolality
Phosphate
controls energy metabolism
Magnesium
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
Kidneys
regulate sodium & potassium balance (excrete potassium in exchange forsodium retention)
Lungs & liver
regulate sodium & water balance & blood pressure
Heart
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
Immeasurable
Ex: through the skin (affected by humidity & body surface area) & lungs (affected by respiratory rate and depth)
Sensible fluid losses
Measurable
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
Isotonic
Hypotonic
Hypertonic
Isotonic
equally concentrated with other solutions
Hypotonic
less concentrated than other solutions
Hypertonic
More concentrated than other solutions
Diffusion
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
Osmosis
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
Aldosterone
secreted by the adrenal cortex regulates sodium & water reabsorption by the kidneys
ADH
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
ANP
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
Thirst
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
Acids
molecules that can give hydrogen molecules to other molecules; include solutions with a pH below 7
Bases
molecules that can accept hydrogen molecules; include solutions with a pH above 7
pH
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
Acidosis
blood pH is below 7.35 & either the hydrogen ion concentration has increased or the bicarbonate level has decreased
Alkalosis
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
Kidneys
Chemical buffers
neutralize the offending acid or base
Respiratory system
regulates retention & excretion of acids
Kidneys
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
Kidneys
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