Copyright © 2015. F.A. Davis Company W ATER C HAPTER 8: W ATER

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


FLUID COMPARTMENTSFLUID COMPARTMENTS

Intracellular Extracellular Interstitial Intravascular Lymphatic Transcellular


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


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


WATER INTOXICATIONWATER INTOXICATION

Excessive water intake—intravenous or gastrointestinal

Cerebral concussion Hormonal disorders


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


WATER BALANCE IN THE BODYWATER BALANCE IN THE BODY

Osmotic pressure—hypotonic, hypertonic, isotonic

Sodium potassium pump Serum electrolytes


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


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.


PLASMA PROTEINS AND WATER PLASMA PROTEINS AND WATER BALANCEBALANCE

Hydrostatic blood pressure—systolic and diastolic

Colloidal osmotic pressure—albumin Malnutrition—kwashiorkor


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


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)


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


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


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


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)


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


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


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.


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


““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


SENSIBLE/INSENSIBLE WATER LOSSESSENSIBLE/INSENSIBLE WATER LOSSES

Sensible Perspiration Urine Gastrointestinal

Insensible Lungs Skin

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Copyright © 2015. F.A. Davis Company W ATER C HAPTER 8: W ATER