This document discusses body fluids and electrolytes. It begins by stating that total body water makes up 60% of body weight and is divided into intracellular fluid (ICF) and extracellular fluid (ECF). ECF can be further divided into plasma and interstitial fluid. The document then discusses the composition of body fluids, measurement techniques, water balance and electrolyte distribution between fluid compartments. It emphasizes the importance of homeostasis and how the kidneys, hormones and hypothalamus help regulate fluid balance and prevent conditions like dehydration or edema.

1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
BODY FLUIDS

2. OBJECTIVES
1. Volumes & Compartments of body fluids
2. Composition of body fluids
3. Measurement of each compartment
4. Significance of body fluids.
5. Water balance – positive and negative
water balance
6. Oedema , Dehydration.
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3. BODY COMPOSITION
60%
7%
18%
15%
BODY COMPOSITION
WATER
MINERALS
PROTEINS
FATS
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4. TOTAL BODY WATER
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5. BODY FLUID COMPARTMENTS
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6. DISTRIBUTION OF TOTAL
BODYY WATER
COMPARTMENTS VOLUME (L) PERCENTAGE
BODY WEIGHT BODY WATER
TOTAL BODY
WATER
42 60 100
ICF 28 40 67
ECF 14 20 33
PLASMA (25%) 3.5 5 8
INTERSTITIAL
FLUID,
TRANSCELLULAR
FLUID,
MESENCHYMAL
TISSUE (75%)
10.5 15 25
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7. PERCENTAGE OF WATER IN THE
BODY
Total Body Water
varies depending on
body fat:
 infant: 73%
 male adult: 60%
 female adult: 40-50%
 effects of obesity
 Old age 45%

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9. MOVEMENT OF BODY FLUIDS
IMPORTANT CONCEPT
 Body fluids are not
static.
 Fluids & electrolytes
shift from
compartment to
compartment.
 Emphasis is always on
maintaining
homeostasis

10. COMPOSITION OF BODY FLUIDS
Body fluids contain water
and solids. Solids are
organic and inorganic
substances.
 ORGANIC SUBSTANCES:
Glucose, amino acids,
fatty acids, hormones
and enzymes.

11. COMPOSITION OF BODY FLUIDS
 INORGANIC SUBSTANCES:
Extracellular fluid contains
large quantity of sodium,
chlorides, bicarbonate,
glucose, fatty acids and
oxygen.
 Intracellular fluid
contains large quantities of
potassium, magnesium,
phosphates, sulphates and
proteins.
PH of ECF is 7.4
PH of ICF is 7

13. SIGNIFICANCE OF BODY FLUIDS
 In Homeostasis: Body
cells survive in the fluid
medium called internal
environment or milieu
interior.
 Growth and functions of
cells Glucose, amino
acids, lipids, vitamins,
ions, oxygen etc., in
proper quantities in the
internal environment.

14. SIGNIFICANCE OF BODY FLUIDS
 In Transport
mechanism: Body
water forms the
transport medium by
which nutrients and
other essential
substances enter the
cells and wastes come
out of the cells.
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15. SIGNIFICANCE OF BODY FLUIDS
 In Metabolic reactions:
water inside the cells
forms the medium for
various metabolic
reactions, which are
necessary for growth
and functional
activities of the cells.

16. SIGNIFICANCE OF BODY FLUIDS
 In Texture of tissues : water
inside the cells is
necessary for the
characteristic form and
texture of various tissues.
 In Temperature
regulation : body water
plays a vital role in the
maintenance of normal
body temperature.
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17. REGULATORY MECHANISMS
 Hypothalamus –Thirst
mechanism
 KIDNEYS
 Kidney Function
 HORMONES
 Renin-Angiotensin-
Aldosterone
 Anti-Diuretic Hormone

18. MEASUREMENT OF BODY FLUIDS
INDICATOR DILUTION METHOD:
V = M
C
V = volume of fluid in the compartment
M = Mass or total quantity of marker substance
injected
C = Concentration of the marker substances in the
sample of fluid
CORRECTED FORMULA:
Volume = Amt. of subs. Amt. of subs.
Injected - excreted
Conc. of subs. in sample of fluid.

19. PRE-REQUISITE FOR ACCURATE
BODY FLUID MEASUREMENTS
 Non-toxic.
 Mix-evenly.
 Relatively easy to
measure.
 No effect on
distribution of water.
 Must be unchanged & if
changed must be
known.
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20. MEASUREMENT OF TOTAL BODY
WATER.
 By injecting marker
which evenly
distribute in all
compartment of body.
 Markers used
 Deuterium Oxide.
 Tritium Oxide.
 Aminopyrine.
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21. MEASUREMENT OF ECF VOLUME.
 Marker should not enter the
cell but freely pass through
capillary membrane.
 Radioactive substances –
Na, Cl, Bromide sulphate,
Thiosulphate
 NON-METABOLIZABLE
saccharides – Inulin (Most
accurate) Mannitol, Sucrose
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22. MEASUREMENT OF PLASMA
VOLUME
 Marker should bind
strongly with plasma
proteins & should not
diffuse into Interstistium.
 Radioactive iodine (I121
)
 Evan’s blue dye
 Radioactive isotopes of
Chromium (Cr51
)
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23. MEASUREMENT OF ICF
 Cannot be measured
directly.
 So ICF = TBW - ECF
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24. MEASUREMENT OF
INTERSTITIAL FLUID VOLUME
 Interstitial fluid
volume =
ECF – Plasma volume.
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25. WATER BALANCE
Body fluid levels are maintained at normal
levels when the intake and output of
water are balanced.
INTAKE OUTPUT
Drinking – 1300 Urine – 1500
Food – 850 Sweat through skin - 500
Metabolic origin – 350 Feces – 100
------------ Expired air - 400
2500 ml ----------
2500ml
When the intake is more than the output then
a positive water balance develops.

26. PHYSIOLOGICAL POSITIVE
WATER BALANCE
 Growth
 Convalescence
 Pregnancy

27. PATHOLOGICAL POSITIVE WATER
BALANCE
 This is referred to as oedema.
Abnormal accumulation of
water in normally existing
space in the body is called
Oedema.
Oedema develops in
 Heart Failure
 Renal failure
 Malnutrition
 Inflammation of tissue

28. OEDEMA
Oedema is mostly extracellular and may develop
due to:
 Increase in capillary hydrostatic pressure
 Decreased colloidal osmotic pressure
 Increased permeability of the capillary
 Lymphatic obstruction
 Failure of kidney to excrete excess water

29. NEGATIVE WATER BALANCE
 PHYSIOLOGICAL NEGATIVE WATER BALANCE:
occurs during exercise, working in hot sun.
 PATHOLOGICAL NEGATIVE WATER BALANCE: is
seen in dehydration, burns, hemorrhage,
vomiting, diarrhea when the output is more
than input, negative water balance develops.

30. DEHYDRATION
Excessive loss of body
water leading to a
decline in body
water level is called
dehydration.
Dehydration may
be due to :
 Simple water loss
 Loss of both water
and electrolytes

31. DEHYDRATION -- EXCESSIVE LOSS OF
BODY WATER IS SEEN IN
 Excess body water loss as
in diarrhea
 Severe vomiting
 Excessive sweating
 Fluid loss in burns
 Addison’s disease
 Diabetes mellitus and
Diabetes insipedus
 Renal disease
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32. The clinical symptoms associated
with severe dehydration are:
 Low cardiac output
 Rapid pulse rate
 Low blood pressure
 Decreased skin turgor
 Acidosis
 Sunken eye balls
 Lethargy, confusion and
coma
 Intracellular
dehydration may lead to
death.

33. Severe Dehydration
TREATMENT:
The replenishment
of body with water
and electrolytes.
Electrolytes and pH
should be monitored
carefully.

34. BODY ELECTROLYTE
 Distribution of ions in ECF & ICF
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IONS ECF ICF
CATIONS
Na+ 142 14
K+ 5.5 150
Ca+ 5 <1
Mg+ 3 58
ANIONS
Cl- 103 4
HCO3 28 10
PO4 4 75
Proteins 5 40

35. INFERENCE
 In ICF major Cations
are K+ & Mg and
major anions PO3 &
Proteins.
 In ECF major Cations
is Na+ and major
anions are Cl- & HCO3
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36. EXCHANGEABLE IONS
 All body K+ is
exchangeable
 65-70% of Na is
Exchangeable.
 All Ca & Mg Non-
exchangeable.
 Only exchangeable
solutes – Osmotically
active.
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37. FUNCTIONS OF ELECTROLYTE.
 Main solutes for acid-
Base maintenance
balance.
 Maintain proper
osmolality & volume of
body fluids.
 Concentration of certain
determine their
physiological function.
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38. Thank you.
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