A comprehensive presentation on Metabolism of water and its clinical significance for MBBS, BDS, B Pharm & Biotechnology students to facilitate self- study.

1. Metabolism of water and
its clinical significance
Dr. Rohini C Sane

2. Water and electrolyte Balance
• The organism possesses tremendous capacity to survive against odds
and maintain homeostasis .
• This is particularly true with regard to water ,electrolyte and acid- base
status of the human body.
• Kidney actively participates in regulation of water ,electrolyte and acid-
base Balance in human body.

3. Water and electrolyte Balance
Water
Electrolyte Balance
Acid base
Functions of kidney

4. Importance of Water

5. Functions of water
1. Powerful solvent for ionic compounds & neutral molecules in organisms( aqueous
medium for biochemical reactions )
2. Strong influence on state of dissociation of macro molecules
3. Influence on structural & functional components of cells ( the major body
constituent)
4. Regulation of body temperature (high heat of vaporization helps in body cooling)
5. Vehicle for transport of solutes

6. Weight contribution by water in a human body (age wise)

7. Weight contribution by water in the human tissue

9. Daily Water transfer in human body

10. Splanchnic and central compartments related with water

11. Distribution of water in a human body (70kg)
CATEGORY WATER CONTENT -WEIGHT CONTRIBUTION (% )
HUMAN 60
MEN 55-70
WOMEN 45-60
COMPARTENT BODY WEIGHT (% ) VOLUME OF H₂O ( LITRES )
Total 60 42
Intracellular fluid ( ICF ) 40 28
Extracellular fluid ( ECF )* 20* 14*
Interstitial fluid * 15* 10.5*
Plasma* 5* 3.5*
Women & obese have less water .( Higher content of stored fat in an anhydrous form)

12. Distribution of water in a human body

13. Distribution of water in a human body (70kg)
The body water compartments
Total body water
(42L )-60% of
body weight
Extracellular
fluid ( ECF )-
(14L )20% of
body weight
Intravascular volume of plasma
2.8L)-4% of body weight
Extravascular or interstitial fluid
11.2L)-16% of body weight
Intracellular fluid
( ICF -28L)-40%
of body weight
One third of ECF
two third of
ECF

14. Distribution of Water in the Body
Extra cellular fluid (ECF )
• Plasma ( one third of
ECF)
• Lymph (1.5 L )
• Bone
• Cartilage
• Trans- vascular fluid
• Interstial fluid & lymph
Intra cellular fluid (ICF )
• Single compartment –
constant composition-
two third of total body
water
Mixing & exchange of nutrients & metabolites waste between plasma & lymph or Interstial fluid
No exchange between plasma & different structures- bone ,cartilage , connective tissue ( a vascularity )

15. Distribution of water in the Body
❖Distribution of water between different compartments depends on
the concentration gradient of solutes on the either side of the
membrane ( osmotic gradient ).

16. Distribution of Body fluid

18. Distribution of water in the Body

20. Comparison of ECF and ICF

21. Trans vascular fluids (1.5L )
1. CSF
2.Synovial fluid
3.Peritoneal fluids
4. Alimentary secretions(Lumen of Gastro intestinal tract)
5.Pleural fluid
6. Aqueous humor

22. 1. CSF

23. 2.Synovial fluid

24. Peritoneal fluids -3

25. Alimentary secretions(Lumen of Gastro intestinal tract) :4

26. Pleural fluid-5

27. Aqueous humor -6

28. Daily intake of Water by the human body in
balanced status
Sources of water to the human body in balanced status:
1. Exogenous water sources
2. Endogenous water sources

29. Daily intake of Water by the human body in
balanced status
Exogenous Sources of water to the human body in balanced status:
1. Ingested water
2. Water content of solid food
3. Beverages
❖Daily intake of Water by the human body 0.5 – 5 L ( depends on social habits
and climates)
Ingestion of water is controlled by a thirst center located in hypothalamus.

30. Endogenous water sources
Endogenous water sources = metabolic water produced within
human body by oxidation of food stuff ( 300- 350 ml / day )
Foodstuff (1 gm ) yield of Endogenous water
on oxidation
Carbohydrate 0.6 ml
Protein 0.4 ml
Lipid 1.1 ml
125 ml of Endogenous water is generated for 1000 Cal consumed by the human body.

31. Metabolic water( endogenous water)
❖Metabolic water due to oxidation of food stuff (1gm )
Carbohydrate
0.6 ml
Protein
0.4ml
Lipid
1.0 ml

32. Regulation of water content in the human body
Regulation of water content in the human body is achieved by
balancing the daily water intake and water output.
• The thirst center located in the third ventricle in hypothalamus ,
which is stimulated by ECF hyperosmaolality and hypovolemia and
inhibited by hypoosmolality and hypervolemia.
• Vasopressin or Antidiuretic hormone (ADH),the anterior pituitary
hormone that enhances water reabsorption in response to an
increase in ECF osmality or hypovolemia.
• Vasopressin secretion is regulated by hypothalamus which responds
to impulses from stretch receptors in left atrium baroreceptors in the
aortic arch and carotid sinus .

33. Thirst center located in the third ventricle in hypothalamus

34. Control of intake of Water by the human body in balanced status
Increased in osmality of plasma
Stimulation of thirst center of hypothalamus
Increased water intake

35. Water output from the human body
❖Routes of elimination of water from the human body
1. urine ( major route)
2. Skin
3. Lungs
4. Feces

36. Water output from the human body

37. Water output through : 1.Urine
❖Urine is a major route of elimination of water from the human
body.
❖Daily output of urine by the human body in balanced status = 1 - 2 L/day
❖Kidney regulates retention and elimination of water from the human body.
❖Water loss by Kidney is highly variable(to get rid of / to retain water).
❖Volume of water as a medium essential to eliminate waste products from
the human body = 500 ml / day
❖The human body cannot stop the production of Urine even if water
intake is nil.

38. Hormonal regulation of excretion of Urine

39. Hormonal regulation of urine production and excretion
Everyday
• 180 L of water filtered by glomeruli into renal tubules
• 178 L of water absorbed by renal tubular cells
• 1-2 L of water excreted as urine (tightly controlled by ADH )

40. Hormonal regulation of excretion of Urine
❖Volume of water filtered by glomeruli into renal tubules of Kidney= 180
L/day ( most of this is reabsorbed and 1-2 L /day is excreted as urine )
❖Vasopressin = Antidiuretic Hormone (ADH ) from posterior pituitary
gland regulates excretion of water by Kidney.

41. Hormonal regulation of excretion of Urine
❖Vasopressin = Antidiuretic Hormone (ADH ) from posterior pituitary
gland regulates excretion of water by Kidney.
Increased in osmality of plasma
Increased in secretion of Antidiuretic Hormone
(ADH ) from posterior pituitary gland
Increased water reabsorption by the renal tubules
Less urine output till homeostasis is achieved

42. Hormonal regulation of excretion of Urine
❖Vasopressin = Antidiuretic Hormone (ADH ) from posterior pituitary
gland regulates excretion of water by Kidney.
Decreased in osmality of plasma
Suppression in secretion of Antidiuretic Hormone
(ADH ) from posterior pituitary gland
Reduced water reabsorption by the renal tubules
more urine output till homeostasis is achieved

43. Hormonal regulation of excretion of Urine
❖Diabetes insipidus : deficiency of ADH  increased loss of
water from body.
❖Plasma osmality is dependent on the sodium concentration
hence sodium indirectly controls the amount of water in the
human body.

45. Water output through :2. skin
❖Skin : loss of water (450 ml /day )through perspiration  an
unregulated process by the body depends upon atmospheric
temperature & humidity
➢↑ atmospheric Temperature  ↑ water loss through skin (loss is
more in hot climate)
➢For every ↑ body Temperature by 1⁰ C(fever)  15% ↑ water loss
through skin

46. Water output through :3. Lungs
❖Water output from Lungs :
Loss of water during Respiration by Lungs  about 400 ml /day in
expired air
✓ Hot climate
✓ Fever water loss through lungs ↑
➢loss of water via skin through perspiration
➢Loss of water via lung through respiration insensible water loss

47. Water output through :4 feces
❖Water output through feces : Water entering in GIT most of it
reabsorbed in intestine  150/ml /day loss through feces in healthy
individual
 Diarrhea  increased fecal loss of water

48. Water balance in the body ( daily intake & output):1
Body H₂O
(4200 ml )
1.Drinking
H₂O &
Beverage
(1500ml )
2. Food stuff
(700ml )
3. Metabolic
water (300ml )
Water intake 2500ml
Water output 2500 ml
Intake of water is controlled by thirst Centre
(part of Hypothalamus )
Water balance of human body is regulated
predominantly by controlling water output
(initially by Obligatory loss via skin , lungs and
feces followed by urinary output).

49. Water balance in the body (daily intake & output):2
Body H₂O
(4200 ml )
Kidney
Urine
( 1500ml)
/day
Skin
(450 ml )
Insensible &
sensible
perspiration
Lungs
( 400ml )
Water vapor
in expired
air
Intestine
Feces
( 150ml )
Starvation : obligatory water loss 
500 ml/day

50. Body H₂O
(4200 ml )
2. Food
stuff
(700ml )
3.
Metabolic
water
(300ml )
1.Drinking
H₂O &
Beverage
(1500ml )
Urine
( 1500ml)
Skin
(450 ml )
Feces
( 150ml )
Lungs
( 400ml )
Water balance in the body : daily intake & output :3
Water intake 2500ml
Water output 2500 ml

51. Abnormalities associated with Water balance
Abnormalities associated with Water balance :
1. Dehydration
2. Overhydration

52. Disorders of water &Electrolyte balance
❖Water & Electrolyte imbalance lead to
➢Dehydration
➢Over hydration
Causes of Water & Electrolyte imbalance:
1. Imbalance of Water intake & output
2. Imbalance of Sodium intake & output

53. • Dehydration is the disturbance of water balance in which the output
exceeds the intake causing a reduction of body water below the normal
level or excessive water loss or both. ( water depletion in the body )
• Dehydration may be as a result of
1.Pure water depletion
( without corresponding loss of electrolytes )
2. Mixed type in which both Water and salt
depletion occur

54. Causes of dehydration
Dehydration may occur as a result of
1. Diarrhea
2. Vomiting
3. Excessive sweating
4. Fluid loss in burns
5. Adreno-corticoid dysfunction
6. Kidney diseases ( e.g. renal insufficiency )
7. Deficiency of ADH ( Diabetes Insipidus )

55. Pure water depletion( without corresponding loss of electrolytes )
A –Decreased water intake of as in
• Elderly debilitated persons
• Unconscious patients
• Severe dysphagia
• Postoperative patients ,when oral
intake has been stopped
B- increased water loss due to
• Sweating ,during fever
• Hyperventilation
• Infantile gastroenteritis
• Diabetes insipidus due to ADH
deficiency
• Diabetes Mellitus due to osmotic
diuresis
• Nephritis
• Acute renal failure
1.Pure water depletion ( without corresponding loss of electrolytes )occurs
under following conditions

56. Biochemical findings in dehydration
❖Biochemical findings in dehydration include
1. Volume of the ECF ( e.g. plasma )decreases with concomitant rise in
electrolyte concentration ( increased ECF osmolality) and osmotic
pressure
2. Water is drawn from intracellular fluid  shrunken cells and disturbed
metabolism( e.g. increased protein breakdown )
3. Increased ADH secretion increased water retention decreased
urinary output (decreased urine volume )
4. Decreased urine sodium
5. Increased concentration of plasma sodium ,protein ( Normal or slight
increased ) and blood urea ( mild)
6. Water depletion often accompanied by loss of electrolytes from body
(Na⁺ ,K⁺ etc.)

59. Dehydration of muscles and nerve
Cells leading to weakness and confusion .
- Oliguria
( and tongue )thirst
Hemoconcentration

60. Consequences of dehydration
❖Consequences of dehydration include :
• increased in plasma sodium and osmality
• Deceased renal flow which stimulates Aldosterone secretion with
increased reabsorption of sodium that aggravates hypernatremia
• Increased in ECF osmolality ,resulting in diffusion of water from the
cells to the ECF

61. Dehydration( vicious cycle )
Sodium
depletion
Anorexia
Vomiting
Loss of NaCl
in vomitus
Salt
depletion

63. Homeostatic mechanisms in dehydration
❖Homeostatic mechanisms in dehydration that compensate
dehydration include:
• Stimulation of thirst center with increased intake of water
• ADH secretion with increased water reabsorption ( except Diabetes
insipidus )

64. Management of Dehydration
• Treatment of choice of dehydration : Intake of plenty of water
• Intravenous administration of isotonic solution (usually 5% glucose ) to
patient who cannot take orally (and should be monitored carefully )
• if dehydration is accompanied by loss of electrolytes : oral/intravenous
administration of isotonic solution (usually 5% glucose ) until urine
volume exceeds 1500ml

65. Management of Dehydration

66. Management of Dehydration in children

67. Management of Dehydration in children

68. Osmotic imbalance and dehydration in Cholera
• Cholera is transmitted through water and food contaminated by the
bacterium Vibrio Cholerae.
• Vibrio Cholerae produces a toxin which stimulate intestinal cells to
secrete various ions ( Cl - , Na+ ,K+,HCO3 - ) into intestinal lumen.

69. Vibrio Cholera

70. Osmotic imbalance and dehydration in Cholera
Vibrio Cholerae produces a toxin which stimulate intestinal cells to secrete various ions
( Cl
-
, Na+,K+,HCO3-) into intestinal lumen
These ions collectively raise the osmotic pressure and suck water into lumen
Diarrhea (heavy loss of water 5-10 L /day )
Loss of dissolved salts and severe dehydration
Death if not treated with oral rehydration therapy (ORT)

71. Overhydration ( water intoxication )
Definition of Overhydration : state of pure water excess or water intoxication
• Retention of large quantity of water  deleterious effects
• excretion large volume of dilute urine ( when water without electrolyte
given )
❖Causes of Overhydration :
a) Excessive intake of large volumes of salt free fluids
b) Renal failure
c) Excessive administration of fluids parenterally
d) Hyper secretion of ADH ( syndrome of inappropriate ADH secretion –
SIADH )
This lead to decrease plasma electrolytes(dilution of ECF &ICF)
↓
Decreased osmolarity

72. Syndrome of inappropriate ADH secretion –SIADH

73. Biochemical tests for Diagnosis of SIADH

74. Overhydration ( water intoxication )

75. Clinical Symptoms of Overhydration ( water intoxication )
1 . Nausea
2. Vomiting
3. Head ache
4.Muscular weakness /lethargy
5. Confusion
7 convulsion
8. Coma
9. Death

76. Biochemical findings in water excess
❖Biochemical findings in water excess include:
• Decrease in plasma sodium
• Increase in ECF volume
• Decrease in plasma proteins
• Decrease in ECF osmolality
• Increase in urine volume
• Decrease in urine sodium: in Addison’s disease
• Increase in urine sodium: other conditions

77. Management in water excess
Management in water excess include :
➢Restriction of water intake
➢Infusion of hypertonic saline if water intoxication occurs

79. Rabies

81. Clinical symptom of Rabies
Hydrophobia is
One of the
diagnostic
symptom of
Rabies

82. Consequences of viral infection in Rabies

83. Management of Rabies

84. Comparison of Overhydration ( water intoxication ) and Dehydration

85. Management of Dehydration and Overhydration ( water intoxication )

86. Cushing's syndrome is associated with Water and sodium retention

87. Overhydration ( water intoxication )