Metabolism of water and its clinical significance

Metabolism of water and its clinical significance

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

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 E l e c t r o l y t e Balance Acid base Functions of kidney

4. Importance of Water

5. Functions of water P o w e rfu l sol v e n t f o r io n ic c o mp o u nd s & n e u t r al m o lec u les in o r g a n isms( a q u e o u s medium for biochemical reactions ) Strong influence on state of dissociation of macro molecules Influence on structural & functional components of cells ( the major body constituent) Regulation of body temperature (high heat of vaporization helps in body cooling) 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 -WEIGHT CONTRIBUTION (% ) HUMAN 60 MEN 55-70 WOMEN 45-60 COMPARTENT BODY WEIGHT (% ) VOLUME OF H ₂ O ( 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 the Body Distribution of water between different compartments depends on the concentration gradient of solutes on the either side of the membrane ( osmotic gradient ).

11. Daily intake of Water by the human body in balanced status Sources of water to the human body in balanced status: Exogenous water sources Endogenous water sources

12. Daily intake of Water by the human body in balanced status Exogenous Sources of water to the human body in balanced status: Ingested water Water content of solid food Beverages Daily intake of Water by the human body  .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 ( 3 00- 35 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 1 000 Cal consumed b y 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. 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

16. Water output from the human body Routes of elimination of water from the human body urine ( major route ) Skin Lungs Feces

17. Water balance in the body ( daily intake & output ) Body H₂O (4200 ml ) 1 . D r i n ki n g 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. Abnormalities associated with Water balance Abnormalities associated with Water balance : Dehydration Overhydration

19. Disorders of water &Electrolyte balance Water & Electrolyte imbalance lead to Dehydration Over hydration Cau s es of W at e r & Elec t r ol y t e imbalanc e : Imbalance of Water intake & output 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 . Mi x ed ty p e in which bot h W at er and salt depletion occur Dehydration

21. Causes of dehydration Dehydration may occur as a result of Diarrhea Vomiting Excessive sweating Fluid loss in burns Adreno -corticoid dysfunction Kidney diseases ( e.g. renal insufficiency ) Deficiency of ADH ( Diabetes Insipidus )

22. Pure water depletion( without corresponding loss 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 Volume of the ECF ( e.g. plasma )decreases with concomitant rise in electrolyte concentration ( increased ECF osmolality) and osmotic pressure Water is drawn from intracellular fluid  shrunken cells and disturbed metabolism( e.g. increased protein breakdown ) Increased ADH secretion  increased water retention  decreased urinary output (decreased urine volume ) Decreased urine sodium Increased concentration of plasma sodium ,protein ( Normal or slight increased ) and blood urea ( mild) 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 Hemoconcentration

25. 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

26. Dehydration( vicious cycle ) Sodium depletion A n o r e x ia V om iti n g Loss of NaCl in vomitus Salt d e p l e t ion

27. 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 )

28. Management of Dehydration

29. Management of Dehydration in 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 Renal failure Excessive administration of fluids parentally 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 inappropriate ADH secretion –SIADH

32. Biochemical tests for Diagnosis of SIADH

33. Overhydration ( water intoxication )

34. Clinical Symptoms of Overhydration ( water intoxication ) 1 . Nausea Vomiting Head ache Muscular weakness /lethargy C o n fusi o n 7 convulsion Coma Death

35. 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

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

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