FLUID AN ELECTROLYTE BALANCE
OBJECTIVES
 List, describe, and compare the body fluid
compartments and their subdivisions
 Discuss avenues by which water enters
and leaves the body and the mechanisms
that maintain fluid balance
 Discuss the nature and importance of
electrolytes in body fluids and explain the
aldosterone mechanism of extracellular
fluid volume control
OBJECTIVES
Explain the interaction between capillary
blood pressure and blood proteins
 Give examples of common fluid imbalances
Fluid Balance
 Required for healthy survival.
 Total volume and distribution of water in the
body remain normal and constant.
 Input must balance output.
 Water is the most abundant compound in the
body.
BODY FLUIDS
 Average body water volume based on healthy
nonobese, 70-kg male (154 lbs)
 Water is 60% of body weight in males
 Water is 50% of body weight in females
 Volume averages 40 L in 70kg male
WATER
VARIATIONS
 Related to total body weight of an individual
 Fat content (Adipose tissue) of the body is
lower in water content.
 Female is 10% less than the male
WATER
VARIATIONS
 Age also accounts for variations
-- Newborn infants, water may account for
80% of total body weight
-- In elderly individuals, the water per pound
of weight decreases
+ Muscle tissue which is high in water is
replaced by fat which is lower in water
BODY FLUIDS
MAJOR FLUID COMPARTMENTS
 Extracellualar Fluid (ECF)
-- Plasma
-- Interstitial fluid (IF)
-- Miscellaneous
- Lymph, joint fluids; cerebrospinal fluid
eye humors
-- Internal environment of the body
-- Surrounds cells and transports substances
to and from them
MAJOR FLUID COMPARTMENTS
 Intracellular Fluid (ICF)
-- Largest fluid compartment
-- Located inside cells
-- Serves as a solvent to facilitate intracellular
chemical reactions
FLUID BALANCE
MECHANISMS
INPUTS AND OUTPUTS
 INPUTS
• Ingested liquids
• Water in foods
• Catabolism
OUTPUTS
•Kidneys
•Lungs
•Skin
•Intestines
FLUID BALANCE
MECHANISMS
URINE VOLUME
 Adjusts to fluid intake
 Anitdiuretic hormone (ADH) from posterior
pituitary glands acts to increase kidney
tubule reabsorption
 Reabsorption will increase extracellular fluid
(total body fluid) which decreases urine volume
FLUID BALANCE
MECHANISMS
ECF
 Increase in sodium concentration tends to
increase the ECF volume by increasing water
movement out of the ICF and increasing ADH
secretion
 The increase in ADH secretion decreases urine
volume which increases ECF volume
FLUID BALANCE
MECHANISMS
CAPILLARY BP
 Pushes water out of blood into IF
 Blood protein concentration pulls water into blood
from IF
 Two forces regulate plasma and IF volume under
usual conditions
IMPORTANCE OF ELECTROLYTES
IN BODY FLUIDS
NONELECTROLYTES
 Organic substances
 Do not break up or dissociate when placed
in water solution
IMPORTANCE OF ELECTROLYTES
IN BODY FLUIDS
ELECTROLYTES
 Compounds that break up or dissociate
in when placed in water solution
 Break into separate particles called “ions”
 Example: Table salt
IMPORTANCE OF ELECTROLYTES
IN BODY FLUIDS
IONS
 Dissociated particles of an electrolyte
 Carry an electrical charge
-- Positive charged ion such as sodium
-- Negative charged ion such as bicarbonate
IMPORTANCE OF ELECTROLYTES
IN BODY FLUIDS
Edema
-Abnormally large amounts of fluid in
the intercellular tissue spaces
-Causes
can be increased
aldosterone secretion
-Increase in capillary blood pressure
-Decrease in plasma protein
Dehydration
-
Too large fluid output, or too small fluid
intake
FLUID IMBALANCES
 Small intake or large output may cause
dehydration.
 Overhydration though less common, causes
many dangers.
FLUID AN ELECTROLYTE BALANCE
Questions
-Where can extracellular fluid be found?
-Approximately what percentage of water does
a healthy non-obese male have?
-Where are some sources the body can receive
water from?
Questions
-What is the function of ADH?
-What is the function of ANH?
-What are the three main factors that effect
fluid volumes?
Questions
-What controls sodium reabsorption in the
kidney?
-How do plasma proteins work in fluid volume
controls?
I.V. FLUIDS/SOLUTIONS
LACTATED RINGERS AND
NORMAL SALINE
• Used to administer IV
medications
• Restores blood volume in
hemorrhage and blood
pressure in shock.
LACTATED RINGERS AND
NORMAL SALINE
• Compensates for fluid loss
from burns
• Combats dehydration
DEXTROSE
• Same use as normal saline
and lactated ringers
• Provides added nutrients
WHOLE BLOOD / PACKED
BLOOD CELLS
• Used to replace blood
• Used to treat shock, burns,
and certain diseases
OTHER BLOOD PRODUCTS
• Fresh frozen plasma
• Platelets
• Blood substitutes
BLOOD SUBSTITUTES
Dextran
• Plasma volume expander
• Used to maintain blood
volume until body
replenishes it or plasma is
obtained.
BLOOD SUBSTITUTES
Albumin
• Blood volume expander
• Used as whole blood
• Contains all blood factors
except red blood cells
• Enhances coagulation
FLUID AND ELECTROLYTE BALANCE
• The End