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Fundamentals of Nursing Taylor 9th Chapter 40
Fundamentals of Nursing (Santa Monica College)
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Chapter 10: Fluid and Electrolytes:
PRINCIPLES OF FLUID, ELECTROLYTES, AND ACID–BASE BALANCE
Water primarily functions:
Transport nutrients to cells and wastes from cells
Transport hormones, enzymes, blood platelets, and red and white blood cells
Facilitate cellular metabolism and proper cellular chemical functioning
Act as a solvent for electrolytes and nonelectrolytes
Help maintain normal body temperature
Facilitate digestion and promote elimination
Act as a tissue lubricant
Body Fluid Compartments
Intracellular fluid (ICF) is the fluid within cells, 70% of total body water (TBW)
Extracellular fluid (ECF) is all the fluid outside the cells, 30% of total body water
Intravascular fluid
Interstitial fluid (includes lymph)
Transcellular fluids
o Cerebrospinal, pericardial, synovial, intraocular, and pleural fluids, sweat and
digestive secretions)
Variations in Fluid Content
Depends on age, body fat, and biological sex.
o Infants: more TBW and ECF; ECF lost more easier higher risk of fluid volume
deficits.
o Fat tissue less water, lean tissue rich more water
Obese patients and women: less water than lean pt and men
Older adults: increased fat tissue, loss of muscle mass less water.
Increased the risk for fluid imbalance
Fluid Balance
Regulated by the thirst mechanism
o Thirst center in hypothalamus stimulated by intracellular dehydration
Nutrition affects water content (fruits vs cereal)
Average fluid intake 2,600 mL /day; Fluid output average 2,600 mL/day
Fluid loss
o sensible losses: urination, defecation, and wounds
o insensible losses: sweat, respiration.
Healthy adults, output = intake; deviations potential imbalances.
Electrolytes: differs based on compartments
o Major ECF players:
Na, Cl, Ca, and HCO3
o Major ICF players:
K, PO4, and Mg
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Regulation and Homeostatic Mechanisms of Fluid and Electrolyte Balance
Mechanisms: osmosis, diffusion, active transport, and capillary filtration
Osmosis:
Major method of transporting body fluids. (key players: semi-permeable membrane)
o Water (the solvent) passes from an area of lesser solute concentration and more
water to an area of greater solute concentration and less water until equilibrium is
established.
o The greater the difference in the concentration of the two solutions on each side of
a semipermeable membrane, the greater the osmotic pressure or drawing power of
water
Osmolarity of solution: concentration of particles in a solution
o osmolarity of plasma (between 275 and 295 mOsm/L)
o if solution is same osmolarity as plasma then its isotonic
An isotonic fluid in the intravascular compartment w/out any net flow across membrane
A hypertonic solution: increased osmolarity than blood (>295 mOsm/L
Net flow of water will be from the ICF to ECF, causing the cells to shrink.
A hypotonic solution: decreased osmolarity than blood (<275 mOsm/L)
Net flow of water will be from the ECF to ICF, hydrates the cells
“osmotic potential,” refers to the electrolytes’ affinity for water (i.e., the capacity to pull
water into a fluid compartment). Key player: Sodium: high osmotic potential
Diffusion:
Solutes move freely throughout a solvent. higher concentration to low
Active transport:
Requires energy cs moves against the concentration gradient (less high),
Capillary filtration
Filtration: the passage of fluid through a permeable membrane.
Results from the force of blood “pushing” against the walls of the capillaries
o At the arterial end of the capillaries, filtration dependent primarily on arterial BP
o At the venular side of the capillaries, filtration dependent on venous BP
Hydrostatic pressure: the “pushing” force
Reabsorption: the process that acts to prevent too much fluid from leaving the capillaries
no matter how high the hydrostatic pressure.
Facilitated by the plasma proteins (e.g albumin) to “pull” fluid back into the capillaries
Colloid osmotic pressure, or oncotic pressure: “pulling” force
Normal conditions:
Hydrostatic pressure in the arteriole end of a capillary > plasma colloid pressure.
o Hydrostatic pressure at the venule end of the capillary < plasma colloid pressure
Result:
Downloaded by kuchy kuchy ()
Fundamentals of Nursing Taylor 9th Chapter 40
Fundamentals of Nursing (Santa Monica College)
Scan to open on Studocu
Studocu is not sponsored or endorsed by any college or university
Downloaded by kuchy kuchy ()
, lOMoARcPSD|53991452
Chapter 10: Fluid and Electrolytes:
PRINCIPLES OF FLUID, ELECTROLYTES, AND ACID–BASE BALANCE
Water primarily functions:
Transport nutrients to cells and wastes from cells
Transport hormones, enzymes, blood platelets, and red and white blood cells
Facilitate cellular metabolism and proper cellular chemical functioning
Act as a solvent for electrolytes and nonelectrolytes
Help maintain normal body temperature
Facilitate digestion and promote elimination
Act as a tissue lubricant
Body Fluid Compartments
Intracellular fluid (ICF) is the fluid within cells, 70% of total body water (TBW)
Extracellular fluid (ECF) is all the fluid outside the cells, 30% of total body water
Intravascular fluid
Interstitial fluid (includes lymph)
Transcellular fluids
o Cerebrospinal, pericardial, synovial, intraocular, and pleural fluids, sweat and
digestive secretions)
Variations in Fluid Content
Depends on age, body fat, and biological sex.
o Infants: more TBW and ECF; ECF lost more easier higher risk of fluid volume
deficits.
o Fat tissue less water, lean tissue rich more water
Obese patients and women: less water than lean pt and men
Older adults: increased fat tissue, loss of muscle mass less water.
Increased the risk for fluid imbalance
Fluid Balance
Regulated by the thirst mechanism
o Thirst center in hypothalamus stimulated by intracellular dehydration
Nutrition affects water content (fruits vs cereal)
Average fluid intake 2,600 mL /day; Fluid output average 2,600 mL/day
Fluid loss
o sensible losses: urination, defecation, and wounds
o insensible losses: sweat, respiration.
Healthy adults, output = intake; deviations potential imbalances.
Electrolytes: differs based on compartments
o Major ECF players:
Na, Cl, Ca, and HCO3
o Major ICF players:
K, PO4, and Mg
Downloaded by kuchy kuchy ()
, lOMoARcPSD|53991452
Regulation and Homeostatic Mechanisms of Fluid and Electrolyte Balance
Mechanisms: osmosis, diffusion, active transport, and capillary filtration
Osmosis:
Major method of transporting body fluids. (key players: semi-permeable membrane)
o Water (the solvent) passes from an area of lesser solute concentration and more
water to an area of greater solute concentration and less water until equilibrium is
established.
o The greater the difference in the concentration of the two solutions on each side of
a semipermeable membrane, the greater the osmotic pressure or drawing power of
water
Osmolarity of solution: concentration of particles in a solution
o osmolarity of plasma (between 275 and 295 mOsm/L)
o if solution is same osmolarity as plasma then its isotonic
An isotonic fluid in the intravascular compartment w/out any net flow across membrane
A hypertonic solution: increased osmolarity than blood (>295 mOsm/L
Net flow of water will be from the ICF to ECF, causing the cells to shrink.
A hypotonic solution: decreased osmolarity than blood (<275 mOsm/L)
Net flow of water will be from the ECF to ICF, hydrates the cells
“osmotic potential,” refers to the electrolytes’ affinity for water (i.e., the capacity to pull
water into a fluid compartment). Key player: Sodium: high osmotic potential
Diffusion:
Solutes move freely throughout a solvent. higher concentration to low
Active transport:
Requires energy cs moves against the concentration gradient (less high),
Capillary filtration
Filtration: the passage of fluid through a permeable membrane.
Results from the force of blood “pushing” against the walls of the capillaries
o At the arterial end of the capillaries, filtration dependent primarily on arterial BP
o At the venular side of the capillaries, filtration dependent on venous BP
Hydrostatic pressure: the “pushing” force
Reabsorption: the process that acts to prevent too much fluid from leaving the capillaries
no matter how high the hydrostatic pressure.
Facilitated by the plasma proteins (e.g albumin) to “pull” fluid back into the capillaries
Colloid osmotic pressure, or oncotic pressure: “pulling” force
Normal conditions:
Hydrostatic pressure in the arteriole end of a capillary > plasma colloid pressure.
o Hydrostatic pressure at the venule end of the capillary < plasma colloid pressure
Result:
Downloaded by kuchy kuchy ()
