424 &' CHAPTER TWENTY ONE
% Extracellular fluid (ECF) includes all body fluids out-
% The Importance of Water
side of cells. In this group are included the following:
Water is important to living cells as a solvent, a transport % Interstitial (in-ter-STISH-al) fluid, or more simply, tis-
medium, and a participant in metabolic reactions. The nor- sue fluid. This fluid is located in the spaces between the
cells in tissues all over the body. It is estimated that tis-
mal proportion of body water varies from 50% to 70% of a
sue fluid constitutes about 15% of body weight.
person s weight. It is highest in the young and in thin, mus-
% Blood plasma, which constitutes about 4% of a per-
cular individuals. In infants, water makes up 75% of the
son s body weight.
total body mass. That s why infants are in greater danger
% Lymph, the fluid that drains from the tissues into the
from dehydration than adults. With increase in the amount
lymphatic system. This is about 1% of body weight.
of fat, the percentage of water in the body decreases, be-
% Fluid in special compartments, such as cerebrospinal
cause adipose tissue holds very little water compared with
fluid, the aqueous and vitreous humors of the eye,
muscle tissue.
serous fluid, and synovial fluid. Together, these make
Various electrolytes (salts), nutrients, gases, waste,
up about 1% to 3% of total body fluids.
and special substances, such as enzymes and hormones,
are dissolved or suspended in body water. The composi-
Fluids are not locked into one compartment. There is
tion of body fluids is an important factor in homeostasis.
a constant interchange between compartments as fluids
Whenever the volume or chemical makeup of these fluids
are transferred across semipermeable cell membranes by
deviates even slightly from normal, disease results. (See diffusion and osmosis (see Fig. 21-1). Also, fluids are lost
Appendix 4, Table 3, for normal values.) The constancy and replaced on a daily basis.
of body fluids is maintained in the following ways:
Checkpoint 21-1 What are the two main compartments into
% The thirst mechanism, which maintains the volume of
which body fluids are grouped?
water at a constant level
% Kidney activity, which regulates the
volume and composition of body
fluids (see Chapter 22, The Urinary
Extracellular fluid
System)
% Hormones, which serve to regulate
fluid volume and electrolytes
% Regulators of pH (acidity and alka- Intestine
linity), including buffers, respiration, Intracellular
fluid
and kidney function
Interstitial
The maintenance of proper fluid (fluid inside
fluid
the cells)
balance involves many of the princi-
ples discussed in earlier chapters, such
(fluid between
Blood plasma
as pH and buffers, the effects of respi-
the cells)
and lymph
ration on pH, tonicity of solutions, and
5% of
15% of
body weight
forces influencing capillary exchange.
body weight
Some of these chapters will be refer-
enced in the following sections. Addi-
tional information follows in Chapter
40% of
22 on the urinary system. body weight
Skin Kidneys
% Fluid Compartments
Lungs
Although body fluids have much in
common no matter where they are lo-
60% of
cated, there are some important differ-
body weight
ences between fluid inside and out-
side cells. Accordingly, fluids are
grouped into two main compartments
(Fig. 21-1):
% Intracellular fluid (ICF) is con-
Figure 21-1 Main fluid compartments showing relative percentage by weight of
tained within the cells. About two-
body fluid. Fluid percentages vary but total about 60% of body weight. Fluids are con-
thirds to three-fourths of all body
stantly exchanged among compartments, and each day fluids are lost and replaced.
ZOOMING IN &' What are some avenues through which water is lost?
fluids are in this category.
BODY FLUIDS &' 425
In many disorders, it is important for the healthcare
% Water Balance
team to know whether a patient s intake and output are
In a person whose health is normal, the quantity of water equal; in such a case, a 24-hour intake output record is
gained in a day is approximately equal to the quantity lost kept. The intake record includes all the liquid the patient
(output) (Fig. 21-2). The quantity of water consumed in a has taken in. This means fluids administered intravenously
day (intake) varies considerably. The average adult in a as well as those consumed by mouth. The healthcare
comfortable environment takes in about 2300 mL of worker must account for water, other beverages, and liquid
water (about 2 1/2 quarts) daily. About two-thirds of this foods, such as soup and ice cream. The output record in-
quantity comes from drinking water and other beverages; cludes the quantity of urine excreted in the same 24-hour
about one-third comes from foods fruits, vegetables, and period as well as an estimation of fluid losses due to fever,
soups. About 200 mL of water is produced each day as a by- vomiting, diarrhea, bleeding, wound discharge, or other
product of cellular respiration. This water, described as causes.
metabolic water, brings the total average gain to 2500 mL
each day.
Checkpoint 21-2 What are three routes for water loss from the
The same volume of water is constantly being lost
body?
from the body by the following routes:
% The kidneys excrete the largest quantity of water lost
Sense of Thirst
each day. About 1 to 1.5 liters of water are eliminated
The control center for the sense of thirst is located in the
daily in the urine. (Note that beverages containing al-
brain s hypothalamus. This center plays a major role in the
cohol or caffeine act as diuretics and increase water loss
regulation of total fluid volume. A decrease in fluid volume
through the kidneys.)
or an increase in the concentration of body fluids stimu-
% The skin. Although sebum and keratin help prevent
lates the thirst center, causing a person to drink water or
dehydration, water is constantly evaporating from the
other fluids containing large amounts of water. Dryness of
skin s surface. Larger amounts of water are lost from the
the mouth also causes a sensation of thirst. Excessive
skin as sweat when it is necessary to cool the body.
thirst, such as that caused by excessive urine loss in cases
% The lungs expel water along with carbon dioxide.
of diabetes, is called polydipsia (pol-e-DIP-se-ah).
% The intestinal tract eliminates water along with the
The thirst center should stimulate enough drinking to
feces.
balance fluids, but this is not always the case. During vig-
orous exercise, especially in hot weather, the body can
dehydrate rapidly. People may not drink enough to re-
Water gain Water loss
place needed fluids. In addition, if plain water is con-
2500 mL/day 2500 mL/day
sumed, the dilution of body fluids may depress the thirst
Metabolism Feces
center. Athletes who are exercising very strenuously may
200 mL 200 mL 21
need to drink beverages with some carbohydrates for en-
Lungs
ergy and also some electrolytes to keep fluids in balance.
300 mL
(See Box 21-1, Osmoreceptors: Thinking About Thirst,
Food
for more about thirst regulation).
700 mL
Skin
500 mL
Checkpoint 21-3 Where is the control center for the sense of
thirst located?
% Electrolytes and Their Functions
Electrolytes are important constituents of body fluids.
These compounds separate into positively and negatively
charged ions in solution. Positively charged ions are called
Drink Urine
cations; negatively charged ions are called anions. Elec-
1600 mL 1500 mL
trolytes are so-named because they conduct an electrical
current in solution. A few of the most important ions are
reviewed next:
% Positive ions (cations):
% Sodium is chiefly responsible for maintaining osmotic
balance and body fluid volume. It is the main positive
ion in extracellular fluids. Sodium is required for nerve
Figure 21-2 Daily gain and loss of water.
426 &' CHAPTER TWENTY ONE
Box 21-1 A Closer Look
Osmoreceptors: Thinking About Thirst
Osmoreceptors: Thinking About Thirst
smoreceptors are specialized neurons that help to main- pituitary. ADH travels to the kidneys and causes these or-
Otain water balances by detecting changes in the concen- gans to conserve water.
tration of extracellular fluid (ECF). They are located in the % They stimulate the thirst center of the hypothalamus, caus-
hypothalamus of the brain in an area adjacent to the third ven- ing increased consumption of water. Almost as soon as
tricle, where they monitor the osmotic pressure (concentra- water consumption begins, however, the sensation of thirst
tion) of the circulating blood plasma. disappears. Receptors in the throat and stomach send in-
Osmoreceptors respond primarily to small increases in hibitory signals to the thirst center, preventing overcon-
sodium, the most common cation in ECF. As the blood be- sumption of water and allowing time for ADH to affect the
comes more concentrated, sodium draws water out of the kidneys.
cells, initiating nerve impulses. Traveling to different regions
Both of these mechanisms serve to dilute the blood and
of the hypothalamus, these impulses may have two different
other body fluids. Either mechanism alone can maintain water
but related effects:
balance. If both fail, a person soon becomes dehydrated.
% They stimulate the hypothalamus to produce antidiuretic
hormone (ADH), which is then released from the posterior
impulse conduction and is important in maintaining
The Role of Hormones Several hormones are in-
acid base balance.
volved in balancing electrolytes (see Chapter 12). Aldos-
% Potassium is also important in the transmission of
terone, produced by the adrenal cortex, promotes the re-
nerve impulses and is the major positive ion in intra- absorption of sodium (and water) and the elimination of
cellular fluids. Potassium is involved in cellular en- potassium. In Addison disease, in which the adrenal cor-
zyme activities, and it helps regulate the chemical re- tex does not produce enough aldosterone, there is a loss
actions by which carbohydrate is converted to energy
of sodium and water and an excess of potassium.
and amino acids are converted to protein.
When the blood concentration of sodium rises above
% Calcium is required for bone formation, muscle con- the normal range, the pituitary secretes more antidiuretic
traction, nerve impulse transmission, and blood clot- hormone (ADH). This hormone increases water reabsorp-
ting.
tion in the kidney to dilute the excess sodium.
% Negative ions (anions):
Hormones from the parathyroid and thyroid glands
% Phosphate is essential in carbohydrate metabolism,
regulate calcium and phosphate levels. Parathyroid hor-
bone formation, and acid base balance. Phosphates are
mone increases blood calcium levels by causing the bones
found in plasma membranes, nucleic acids (DNA and
to release calcium and the kidneys to reabsorb calcium.
RNA) and ATP.
The thyroid hormone calcitonin lowers blood calcium by
% Chloride is essential for the formation of hydrochlo- causing calcium to be deposited in the bones.
ric acid in the stomach. It also helps to regulate fluid
Checkpoint 21-6 What are some mechanisms for regulating
balance and pH. It is the most abundant anion in extra-
electrolytes in body fluids?
cellular fluids.
Checkpoint 21-4 What is the main cation in extracellular fluid?
In intracellular fluid?
% Acid Base Balance
The pH scale is a measure of how acidic or basic (alka-
Checkpoint 21-5 What is the main anion in extracellular fluid?
line) a solution is. As described in Chapter 2, the pH scale
measures the hydrogen ion (H ) concentration in a solu-
tion. Body fluids are slightly alkaline in a pH range of 7.35
Electrolyte Balance
to 7.45. These fluids must be kept within a narrow range
The body must keep electrolytes in the proper concentra-
of pH, or damage, even death, will result. A shift in either
tion in both intracellular and extracellular fluids (see Box
direction by three tenths of a point on the pH scale, to7.0
21-2). The maintenance of water and electrolyte balance
or 7.7, is fatal.
is one of the most difficult problems for health workers in
caring for patients. Although some electrolytes are lost in
Regulation of pH
the feces and through the skin as sweat, the job of bal-
ancing electrolytes is left mainly to the kidneys, as de- The body constantly produces acids in the course of me-
tabolism. Catabolism of fats yields fatty acids and other
scribed in Chapter 22 on the urinary system.
BODY FLUIDS &' 427
Box 21-2 Clinical Perspectives
Sodium and Potassium: Causes and Consequences of Imbalance
Sodium and Potassium: Causes and Consequences of Imbalance
The term hyperkalemia is taken from the Latin name for
he concentrations of sodium and potassium in body fluids
potassium, kalium. It refers to excess potassium in body flu-
Tare important measures of water and electrolyte balance.
ids, which may result from kidney failure, dehydration, and
An excess of sodium in body fluids is termed hypernatremia,
taken from the Latin name for sodium, natrium. This condi- other causes. Its signs and symptoms include nausea, vomit-
ing, muscular weakness, and severe cardiac arrhythmias. Hy-
tion accompanies dehydration and severe vomiting and may
cause hypertension, edema, convulsions, and coma. Hypona- pokalemia, or low potassium in body fluids, may result from
taking diuretics, which cause potassium to be lost along with
tremia, a deficiency of sodium in body fluids, can come from
water. It may also result from pH imbalance or secretion of too
water intoxication, heart failure, kidney failure, cirrhosis of
much aldosterone from the adrenal cortex, and it causes mus-
the liver, pH imbalance, or endocrine disorders. It can cause
muscle weakness, hypotension, confusion, shock, convul- cle fatigue, paralysis, confusion, hypoventilation, and cardiac
arrhythmias.
sions, and coma.
acidic byproducts; cellular respiration yields pyruvic acid body fluids to less than pH 7.35. This condition depresses
and, under anaerobic conditions, lactic acid; carbon diox- the nervous system, leading to mental confusion and ul-
ide dissolves in the blood and yields carbonic acid (see timately coma. Acidosis may result from a respiratory ob-
Chapter 18). Conversely, a few abnormal conditions may struction or any lung disease which prevents the release
result in alkaline shifts in pH. Several systems act to- of CO2. It may also arise from kidney failure or prolonged
gether to counteract these changes and maintain acid- diarrhea, which drains the alkaline contents of the intes-
base balance: tine. Long-term excessive exercise under anaerobic con-
ditions can produce lactic acidosis.
% Buffer systems. Buffers are substances that prevent
Acidosis may also result from inadequate carbohy-
sharp changes in hydrogen ion (H ) concentration and
drate metabolism, as occurs in diabetes mellitus, inges-
thus maintain a relatively constant pH. Buffers work by
tion of a low-carbohydrate diet, or starvation. In these
accepting or releasing these ions as needed to keep the
cases, the body metabolizes too much fat and protein
pH steady. The main buffer systems in the body are bi-
from food or body materials, leading to the production of
carbonate buffers, phosphate buffers, and proteins,
excess acid. When acidosis results from the accumulation
such as hemoglobin in red blood cells and plasma pro-
of ketone bodies, as in the case of diabetes, the condition
teins.
is more accurately described as ketoacidosis.
% Respiration. The role of respiration in controlling pH
Alkalosis (al-kah-LO-sis) results from an increase
21
was described in Chapter 18. Recall that carbon dioxide
in pH to greater than 7.45. This abnormality excites the
release from the lungs makes the blood more alkaline
nervous system to produce tingling sensations, muscle
by reducing the amount of carbonic acid formed. In
twitches, and eventually paralysis. The possible causes of
contrast, carbon dioxide retention makes the blood
alkalosis include hyperventilation (the release of too much
more acidic. Respiratory rate can adjust pH for short- carbon dioxide), ingestion of too much antacid, and pro-
term regulation. longed vomiting with loss of stomach acids.
% Kidney function. The kidneys regulate pH by reabsorb- It is convenient to categorize acidosis and alkalosis as
ing or eliminating hydrogen ions as needed. The kid- having either respiratory or metabolic origins. Respiratory
neys are responsible for long-term pH regulation. The acidosis or alkalosis results from either an increase or a de-
activity of the kidneys is described in
Chapter 22.
Table 21" 1
Causes of Acidosis and Alkalosis
ACIDOSIS ALKALOSIS
Checkpoint 21-7 What are three mecha-
nisms for maintaining the acid base bal-
ance of body fluids? Metabolic Kidney failure; anaerobic me- Overuse of antacids; prolonged
tabolism; lack of carbohy- vomiting
drate metabolism, as in dia-
Abnormal pH
betes, starvation; prolonged
diarrhea
If shifts in pH cannot be controlled, ei-
Respiratory Respiratory obstruction, lung Hyperventilation (overbreathing
ther acidosis or alkalosis results (Table
disease such as asthma due to anxiety or oxygen
21-1).
or emphysema, apnea or deficiency)
decreased ventilation
Acidosis (as-ih-DO-sis) is a condi-
tion produced by a drop in the pH of
428 &' CHAPTER TWENTY ONE
crease in blood CO2. Metabolic acidosis or alkalosis results % Increased loss of fluid through the capillaries, as caused
from unregulated increases or decreases in any other acids by injury, allergic reaction, or certain infections.
(see Table 21-1).
Water intoxication involves dilution of body fluids in
both the intracellular and extracellular compartments.
Checkpoint 21-8 What are the conditions that arise from ab- Transport of water into the cells results in swelling. In the
normally low or high pH of body fluids?
brain, cellular swelling may lead to convulsions, coma,
and finally death. Causes of water intoxication include an
excess of ADH and intake of excess fluids by mouth or by
% Disorders of Body Fluids intravenous injection.
Effusion (e-FU-zhun) is the escape of fluid into a cav-
Edema is the accumulation of excessive fluid in the inter-
ity or a space. An example is pleural effusion, fluid within
cellular spaces (Fig. 21-3). Some causes of edema are as
the pleural space; in this condition fluid compresses the
follows:
lung, so that normal breathing is not possible. Tubercu-
losis, cancer, and some infections may give rise to effu-
% Interference with normal fluid return to the heart, as
sion. Effusion into the pericardial sac, which encloses the
caused by congestive heart failure or blockage in the ve-
heart, may occur in autoimmune disorders, such as lupus
nous or lymphatic systems (see Chapters 14 and 15). A
erythematosus and rheumatoid arthritis. Infection is an-
backup of fluid in the lungs, pulmonary edema, is a se-
other cause of pericardial effusion. The fluid may inter-
rious potential consequence of congestive heart failure.
fere with normal heart contractions and can cause death.
% Lack of protein in the blood. This deficiency may result
Ascites (ah-SI-teze) is effusion with accumulation of
from protein loss or ingestion of too little dietary pro-
fluid within the abdominal cavity. It may occur in disor-
tein for an extended period. It may also result from fail-
ders of the liver, kidneys, and heart, as well as in cancers,
ure of the liver to manufacture adequate amounts of the
infection or malnutrition.
protein albumin, as frequently occurs in liver disease.
Dehydration (de-hi-DRA-shun), a severe deficit of
The decrease in protein lowers the blood s osmotic
body fluids, will result in death if it is prolonged. The
pressure and reduces fluid return to the circulation. Di-
causes include vomiting, diarrhea, drainage from burns
minished fluid return results in accumulation of fluid
or wounds, excessive perspiration, and inadequate fluid
in the tissues.
intake, as in cases of damage to the thirst mechanism. In
% Kidney failure, a common clinical cause of edema, re-
such cases, it may be necessary to administer intravenous
sulting from the inability of the kidneys to eliminate
fluids to correct fluid and electrolyte imbalances.
adequate amounts of urine
Checkpoint 21-9 What is edema?
% Fluid Therapy
Chapter 3 discussed the rules concerning movement of
water into and out of cells when they are placed in differ-
ent solutions. Recall that an isotonic solution has the
same concentration as the cellular fluids and will not
cause a net loss or gain of water. A hypertonic solution is
more concentrated than cellular fluid and will draw water
out of the cells. A hypotonic solution is less concentrated
than the cellular fluids and a cell will take in water when
placed in this type of solution. These rules must be con-
sidered when fluid is administered.
Fluids are administered into a vein under a wide variety
of conditions to help maintain normal body functions when
natural intake is not possible. Fluids are also administered
to correct specific fluid and electrolyte imbalances in cases
of losses due to disease or injury. (Box 21-3, Emergency
Medical Technicians, focuses on a healthcare professional
Figure 21-3 Edema of the foot. (Reprinted with permission
whose role may include administering fluids.)
from Bickley LS. Bates Guide to Physical Examination and His-
The first fluid administered intravenously in emer-
tory Taking. 8th ed. Philadelphia: Lippincott Williams &
Wilkins, 2003.)
gencies is normal saline, which contains 0.9% sodium
BODY FLUIDS &' 429
Box 21-3 " Health Professions
Emergency Medical Technicians
Emergency Medical Technicians
travenous fluids, oxygen, and certain life-saving medications.
mergency medical technicians (EMTs) are the first health
At medical facilities, EMTs work closely with physicians and
Eprofessionals to arrive at the scene of an automobile accident,
nurses, reporting on histories, physical examinations, and
heart attack, or other emergency situation. EMTs must assess and
respond rapidly to a medical crisis, taking a medical history, per- measures taken to stabilize the patient. Most EMTs receive
their training from a college or technical school and must be
forming a physical examination, stabilizing the patient, and, if
certified in the state where they are employed.
necessary, transporting the patient to the nearest medical facility.
As the American population continues to age and become
To perform their life-saving duties, EMTs need extensive
concentrated in urban centers, the rate of accidents and other
training, including a thorough understanding of anatomy and
physiology. EMTs must know how to use specialized equip- emergencies is expected to rise. Thus, the need for EMTs re-
ment, such as backboards to immobilize injuries, electrocar- mains high. For more information about this rewarding ca-
reer, contact the National Association of Emergency Medical
diographs to monitor heart activity, and defibrillators to treat
cardiac arrest, and they must also be proficient at giving in- Technicians.
chloride, a concentration equal to that of plasma. Because calcium, chloride, and lactate. In this formulation, the
it is isotonic, this type of solution does not change the ion electrolyte concentrations are equal to normal plasma val-
distribution in the body fluid compartments. ues. The lactate is metabolized to bicarbonate, which acts
Frequently, a patient receives 5% dextrose (glucose) as a buffer. This fluid is given when the need is for addi-
in 0.45% (1/2 normal) saline. This solution is hypertonic tional plasma volume with the electrolyte concentration
when infused, but becomes hypotonic after the sugar is equal to that of the blood.
metabolized. Another common fluid is 5% dextrose in In 25% serum albumin, the concentration of the
water. This solution is slightly hypotonic when infused. plasma protein albumin is five times normal. This hyper-
The amount of sugar contained in a liter of this fluid is tonic solution draws fluid from the interstitial spaces into
equal to 170 calories. The sugar is soon used up, result- the circulation.
ing in a fluid that is effectively pure water. Use of these Fluids containing varied concentrations of dextrose,
hypotonic fluids is not advisable for long-term therapy sodium chloride, potassium, and other electrolytes and
because of the common occurrence of water intoxication. substances are manufactured. These fluids are used to
Both these dextrose solutions increase the plasma fluid correct specific imbalances. Nutritional solutions con-
volume. Small amounts of potassium chloride are often taining concentrated sugar, protein, and fat are available
added to replace electrolytes lost by vomiting or diarrhea. for administration when oral intake is not possible for an
21
Ringer lactate solution contains sodium, potassium, extended period.
Word Anatomy
Medical terms are built from standardized word parts (prefixes, roots, and suffixes). Learning the meanings of these parts can help you
remember words and interpret unfamiliar terms.
WORD PART MEANING EXAMPLE
Fluid Compartments
intra- within Intracellular fluid is within a cell.
extra- outside of, beyond Extracellular fluid is outside the cells.
semi- partial, half A semipermeable membrane is partially permeable.
Water Balance
poly- many Polydipsia is excessive thirst.
osmo- osmosis Osmoreceptors detect changes in osmotic concentration of fluids.
Acid-Base Balance
-o/sis condition, process Acidosis is a condition produced by a drop in the pH of body fluids.
Disorders of Body Fluids
tox/o poison Water intoxication is dilution of body fluids by excess water.
hydr/o water Dehydration is a severe deficit of body fluids.
430 &' CHAPTER TWENTY ONE
Summary
4. Calcitonin (from thyroid)
I. The importance of water
a. Decreases blood calcium level
A. Functions
1. Solvent
V. Acid base balance
2. Transport medium
A. Normal pH range is 7.35-7.45
3. Participant in metabolic reactions
1. Regulation of pH
B. 50% to 70% of body weight
B. Buffers maintain constant pH
C. Contains electrolytes, nutrients, gases, wastes, hormones,
C. Respiration release of carbon dioxide increases alkalinity;
and other substances
retention of carbon dioxide increases acidity
D. Important in homeostasis
D. Kidney regulates amount of hydrogen ion excreted
1. Abnormal pH
II. Fluid compartments
E. Acidosis decrease in pH; causes: respiratory obstruction,
A. Intracellular fluid contained within the cells
lung disease, kidney failure, diarrhea, diabetes mellitus,
B. Extracellular fluid outside the cells
starvation
1. Blood plasma
F. Alkalosis increase in pH; causes: hyperventilation, inges-
2. Interstitial (tissue) fluid
tion of antacids, prolonged vomiting
3. Lymph
4. Fluid in special compartments
VI. Disorders of body fluids
A. Edema accumulation of fluid in tissues
III. Water balance
1. Causes
A. Loss through kidneys, skin, lungs, intestinal tract,
a. Interference with fluid return to heart
B. Gain through beverages, food, metabolic water
b. Lack of proteins in blood
1. Sense of thirst
c. Kidney failure
C. Control center in hypothalamus
d. Fluid loss from capillaries
D. Responds to fluid volume and concentration of body fluids
B. Water intoxication dilution of body fluids
C. Effusion escape of fluid into a cavity or space
IV. Electrolytes and their functions
D. Ascites accumulation of fluid in abdominal cavity
A. Electrolytes release ions in solution
E. Dehydration deficiency of fluid
1. Positive ions (cations) e.g., sodium, potassium, cal-
cium
VII. Fluid therapy
2. Negative ions (anions) e.g., phosphate, chloride
A. Purpose
a. Electrolyte balance
1. Correct fluid balance
B. Kidneys main regulators
2. Correct electrolyte balance
C. Role of hormones
3. Provide nourishment
1. Aldosterone (from adrenal cortex)
B. Commonly used solutions
a. Promotes reabsorption of sodium
1. Normal saline
b. Promotes excretion of potassium
2. 5% dextrose (glucose) in 0.45% (1/2 normal) saline
2. ADH (from pituitary)
3. 5% dextrose in water
a. Causes kidney to retain water
4. Ringer lactate
3. Parathyroid hormone (from parathyroid glands)
5. 25% serum albumin
a. Increases blood calcium level
Questions for Study and Review
Building Understanding
Fill in the blanks
4. Effusion with accumulation of fluid within the ab-
1. Excessive thirst is termed______.
dominal cavity is termed ______.
2. Loss of sodium and an excess of potassium are classic
5. A severe deficit in body fluid is called ______.
signs of ______ disease.
3. Substances in the blood that prevent sharp changes in
hydrogen ion concentration are called______.
BODY FLUIDS &' 431
Matching
Match each numbered item with the most closely related lettered item.
___ 6. Essential for maintaining osmotic balance and body fluid volume; this cation is
abundant in extracellular fluid a. sodium
___ 7. Important in the transmission of nerve impulses and enzyme activities; this cation b. potassium
is abundant in intracellular fluid c. calcium
___ 8. Required for bone formation, muscle contraction, and blood clotting d. phosphate
___ 9. Essential in bone formation and acid-base balance; this anion is found in plasma e. chloride
membranes, ATP and nucleic acids
___ 10. Important for gastric acid formation; this anion is abundant in extracellular fluid
Multiple choice
Understanding Concepts
___ 11. Body water content is greatest in
16. Compare the terms in each of the following pairs:
a. infants
a. intracellular and extracellular fluid
b. children
b. aldosterone and antidiuretic hormone
c. young adults
c. calcitonin and parathyroid hormone
d. elderly adults
17. In a healthy person, what is the ratio of fluid intake
___ 12. Fluid located in the spaces between the cells is
to output?
called
18. Explain the role of the hypothalamus in water bal-
a. cytoplasm
ance.
b. plasma
19. How do the respiratory and urinary systems regulate
c. interstitial fluid
pH?
d. lymph
20. Compare and contrast the following disorders:
___ 13. The organ(s) responsible for water loss through
a. acidosis and alkalosis
evaporation is (are) the
b. edema and effusion
a. kidneys
c. water intoxication and dehydration
b. skin
21. List some causes of edema.
c. lungs
22. List three purposes for administering intravenous
d. intestinal tract
fluids.
___ 14. Which of the following is responsible for long- 23. Compare and contrast the following types of intra-
term regulation of pH?
venous fluids:
a. buffer system
a. normal saline and 5% dextrose saline
b. digestive system
b. Ringer solution and serum albumin
c. respiratory system
Conceptual Thinking
d. urinary system
21
24. Patty Grant, 55 years old, reports severe headaches
___ 15. Increased blood CO2 causes
and excessive thirst and urination. What is the probable
a. respiratory acidosis
cause of Patty s symptoms?
b. respiratory alkalosis
25. Why is emphysema associated with decreased urine
c. metabolic acidosis
pH?
d. metabolic alkalosis
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