Metabolism of water and its clinical significance

1. Metabolism
of
waterand
its
clinical
significance
Presented by:
komal zulfiqar

2. Water and electrolyteBalance
• 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 electrolyteBalance
Water
Electroly
te
Balance
Acid
base
Functions of kidney

4. Importance ofWater

5. Functions ofwater
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

8. Distribution of water in a human body(70kg)
CATEGORY WATER CONTENT -WEIGHTCONTRIBUTION (% )
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)

9. Distribution of Water in the Body
Extra cellular fluid (ECF) Intra cellular fluid (ICF )
• Plasma ( one third of
ECF)
• Lymph (1.5 L )
• Bone
• Cartilage
• Trans- vascular fluid
• Interstial fluid & lymph
• 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 )

10. Distribution of water in theBody
Distribution of water between different compartments
depends on the concentration gradient of solutes on the
either side of the membrane ( osmotic gradient ).

11. Dailyintakeof Waterby thehuman body
in balancedstatus
Sources of water to the human body in balanced status:
1. Exogenous water sources
2. Endogenous water sources

12. Dailyintakeof Waterby thehuman body
in balancedstatus
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.

13. 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.

14. 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 .

15. Controlof intakeof Waterby the humanbody in balancedstatus
Increased in osmality of plasma
Stimulation of thirst center of hypothalamus
Increased water intake

16. 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

17. Water balance in the body ( daily intake & output)
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).

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

19. 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

20. • 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

21. Causes ofdehydration
 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 )

22. Purewaterdepletion( without correspondingloss of electrolytes)
• Elderly debilitated persons
• Unconscious patients
• Severe dysphagia
• Postoperative patients ,when
oral intake has been stopped
• 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
A –Decreased water intake B- increased water loss

23. 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.)

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

25. Consequences ofdehydration
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
• Increasedin ECF osmolality ,resulting in diffusion of water
from the cells to the ECF

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

27. Homeostatic mechanisms indehydration
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 )

28. Management of Dehydration

29. Management of Dehydrationin children

30. Overhydration ( water intoxication)
Definition of Overhydration : state of pure water excess or
water intoxication
 Causes of Overhydration
 Excessive intake of large volumes of salt free fluids
a) Renal failure
b) Excessive administration of fluids parentally
c) Hyper secretion of ADH ( syndrome of inappropriate ADH secretion –SIADH )
 This lead to decrease plasma electrolytes(dilution of ECF &ICF)
↓
 Decreased osmolarity

31. Syndrome of inappropriateADH secretion –SIADH

32. Biochemical tests for Diagnosis of SIADH

33. Overhydration ( water intoxication )

34. 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

35. Biochemical findings inwater excess
Biochemical findings in water excess include:
• Decrease in plasma sodium
• Increasein 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

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

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