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Copyright © 2015. F.A. Davis CompanyCopyright © 2015. F.A. Davis Company
CHAPTER 8:
WATERWATER
Copyright © 2015. F.A. Davis Company
WATERWATER
Single largest body substance More than half body weight Muscle tissue is 70% water Fat tissue is 30% water Bone tissue is 10% water
Copyright © 2015. F.A. Davis Company
FLUID COMPARTMENTSFLUID COMPARTMENTS
Intracellular Extracellular Interstitial Intravascular Lymphatic Transcellular
Copyright © 2015. F.A. Davis Company
FUNCTIONSFUNCTIONS
Gives the body shape and form Helps maintain blood volume and pressure Serves as a lubricant Helps regulate body temperature Acts as a solvent for minerals, glucose, and
other small molecules
Copyright © 2015. F.A. Davis Company
ABSORPTIONABSORPTION
Small amount in the bloodstream Larger amounts from the intestines Retained in certain disease processes
(edema) of interstitial fluid: Heart failure Kidney diseases Lymphatic/venous blockages Sodium retention Protein deficiency
Copyright © 2015. F.A. Davis Company
WATER INTOXICATIONWATER INTOXICATION
Excessive water intake—intravenous or gastrointestinal
Cerebral concussion Hormonal disorders
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DIETARY REFERENCE INTAKESDIETARY REFERENCE INTAKES 80% from fluid intake 20% from food intake Increase consumption when physically active Infants receive adequate amounts via
breast milk Watch older adults because thirst mechanism
may be altered
Copyright © 2015. F.A. Davis Company
WATER BALANCE IN THE BODYWATER BALANCE IN THE BODY
Osmotic pressure—hypotonic, hypertonic, isotonic
Sodium potassium pump Serum electrolytes
Copyright © 2015. F.A. Davis Company
CLICKER QUESTIONCLICKER QUESTION
It is especially important to monitor the elderly for fluid balance because of:
A.Potential for changes in body temperatureB.Changes in skin turgorC.Potential for alterations in thirst mechanismD.Cognitive changes
Copyright © 2015. F.A. Davis Company
ANSWERANSWER
Correct Answer: C
Potential for alterations in thirst mechanismRationale: The thirst mechanism is the body’s way of helping to maintain water balance, and this can be altered in the elderly.
Copyright © 2015. F.A. Davis Company
PLASMA PROTEINS AND WATER PLASMA PROTEINS AND WATER BALANCEBALANCE
Hydrostatic blood pressure—systolic and diastolic
Colloidal osmotic pressure—albumin Malnutrition—kwashiorkor
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WATER BALANCEWATER BALANCEINTAKE AND EXCRETIONINTAKE AND EXCRETION
Intake—thirst mechanism Excretion—two hormones
Aldosterone—causes body retain sodium Antidiuretic hormone—causes body
retain/reabsorb water
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WATER IMBALANCESWATER IMBALANCES
Diabetes insipidus - A chronic metabolic disorder causing intense thirst and excessive urination, caused by a deficiency of the pituitary hormone vasopressin.
Syndrome of inappropriate antidiuresis hormone (SIAD)
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SIAD CAUSESSIAD CAUSES Central nervous system disorders (infections,
hemorrhage, multiple sclerosis) Lung disease (pneumonia, tuberculosis,
cystic fibrosis) Some tumors (oat cell of lung, carcinoma of
pancreas, lymphoma, leukemia) Certain drugs (selective serotonin reuptake
inhibitors or SSKIs [saturated solution of potassium iodines], chemotherapeutic agents, antidepressants)
Surgery-induced severe nausea, pain
Copyright © 2015. F.A. Davis Company
ACID–BASE BALANCEACID–BASE BALANCE
Acidity or alkalinity is measured by a scale called pH for potential of hydrogen
The pH scale ranges from 0 to 14: Acids are rated 0 to 6.999; 7.0 is neutral Bases (alkalis) are greater than 7
Copyright © 2015. F.A. Davis Company
EXTRACELLULAR FLUIDEXTRACELLULAR FLUID
The normal pH of the extracellular fluid is 7.35 to 7.45
The body continually works to maintain pH within a narrow range
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RESPIRATORY SYSTEMRESPIRATORY SYSTEM
The lungs help maintain pH The respiratory response to acidosis begins
within minutes The first-aid recommended for
hyperventilation resulting from anxiety is breathing through only one nostril with the mouth closed. The previous technique, breathing into a paper bag, can lead to hypoxia (Venes, 2013)
Copyright © 2015. F.A. Davis Company
RENAL SYSTEMRENAL SYSTEM
The kidney excretes or retains hydrogen, sodium, and bicarbonate ions to maintain pH in blood
The kidneys initiate these actions within 24 hours
Require 3 to 4 days to compensate for changes in blood pH
Copyright © 2015. F.A. Davis Company
CLICKER QUESTIONCLICKER QUESTION
The two body systems most closely effecting pH are:
A.Gastrointestinal and renalB.Renal and cardiacC.Respiratory and cardiacD.Renal and respiratory
Copyright © 2015. F.A. Davis Company
ANSWERANSWER
Correct Answer: D
Renal and respiratoryRationale: Renal (more slowly) and respiratory (more rapidly) perform functions to bring the body pH back into a narrow margin of balance.
Copyright © 2015. F.A. Davis Company
WATER BALANCE/IMBALANCEWATER BALANCE/IMBALANCE
Daily weight is the single most important indicator of fluid status
Weight changes can be caused by metabolic events as well as by fluid shifts
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““THIRD” SPACE LOSSESTHIRD” SPACE LOSSES
Large amounts of fluid can accumulate in several places in the body outside the circulatory system
Third-space losses involve internal bleeding, collection of fluid in the chest cavity, or abdomen ascites - an abnormal accumulation of fluid in the abdomen.
An alert nurse can spot an early clue to third-space losses: decreasing urine output despite seemingly adequate fluid intake
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SENSIBLE/INSENSIBLE WATER LOSSESSENSIBLE/INSENSIBLE WATER LOSSES
Sensible Perspiration Urine Gastrointestinal
Insensible Lungs Skin