1. BODY FLUIDS

3. FACTORS AFFECTING Total Body Water varies depending on body fat:
infant: 73%
male adult: 60%
female adult: 40-50%
effects of obesity
Old age 45%

4. FLUID EXCHANGE BETWEEN BODY FLUID COMPARTMENTS
FLUIDS and ELECTROLYTES
FLUID EXCHANGE BETWEEN BODY FLUID COMPARTMENTS
ICF
ECF P
ISF
Osmotic Pressure Gradient
Oncotic P (Colloid osmotic P)
Capillary P (Hydrostatic P)

5. Control of Osmotic Pressure, Volume & Electrolyte Concentration
FLUIDS and ELECTROLYTES
Control of Osmotic Pressure, Volume & Electrolyte Concentration
OBLIGATORY Reabsorption
occurs in the proximal tubules
178 L/day of glomerular filtrate (80% reabsorbed)
2 to solute reabsorption
independent of the water requirement
FACULTATIVE Reabsorption
occurs in the distal & collecting tubules
independent of the active solute transport
dependent of body’s need of water
under the control of ADH

6. IMPORTANCE
Maintaining ECF volume is critical to maintaining blood pressure
ECF osmolarity is of primary importance in long-term regulation of ECF volume
ECF osmolarity maintained mainly by NaCl balance:

7. FLUID COMPARTMENTS EXTRA CELLUAR INTRA CELLULAR FLUID FLUID
PLASMA
INTERSTITIAL
FLUID
TRANSCELLULAR
FLUID
CSF
Intra ocular
Pleural
Peritoneal
Synovial
Digestive Secretions

9. VOLUME OF BODY FLUIDS IN 70 kg MAN
TOTAL VOLUME
42 L
INTRA CELLUAR FLUID
28 L(ROUGHLY 2/3 OF TBW)
EXTRA CELLULAR FLUID
14 L(ROUGHLY 1/3 OF TBW)
PLASMA
4 L (ROUGHLY ¼ OF ECF)

10. VOLUME MEASUREMENT OF VARIOUS FLUIDS COMPARTMETNS
INTERSTITIAL FLUID
ECF – Plasma Volume
INTRACELLULAR FLUID
TBW – ECF

11. TOTAL BODY WATER(TBW)
60% OF THE BODY WEIGHT IN ADULT MALE
50% OF THE BODY WEIGHT IN ADULT FEMALE

12. 0.9% sodium chloride (NSS) Lactated Ringer’s sol’n Hypotonic
FLUIDS and ELECTROLYTES
IV FLUID REPLACEMENT THERAPY
Types of Solutions
Isotonic
0.9% sodium chloride (NSS)
Lactated Ringer’s sol’n
Hypotonic
5% dextrose and water (D5W)
0.45% sodium chloride
0.33% sodium chloride
Hypertonic
3% NaCl
Protein sol’ns
Colloids
Salt pour albumin Plasmanate, Dextran

13. Factors affecting ADH release

14. REGULATION OF FLUID INTAKE (THIRST)
decreased salivation
decreased blood volume
increased blood osmotic pressure
dry mouth and throat
decreased blood pressure
stimulation of hypothalamic osmoreceptors
conscious awareness of thirst
increased water intake
stimulation of tactile receptors
increased angiotensin II
stimulation of hypothalamic thirst center

15. REGULATION OF FLUID OUTPUT
dehydration
ANTIDIURETIC HORMONE
increased blood osmolarity
stimulation of hypothalamic osmoreceptors
rehydration
secretion of ADH from posterior pituitary gland
increased water reabsorption
increased thirst
ALDOSTERONE
dehydration
rehydration
increased water reabsorption
increased Na+ reabsorption
increased aldosterone
increased angiotensin II
ATRIAL NATRIURETIC PEPTIDE
increased blood volume
decreased Na+ reabsorption
decreased water reabsorption
decreased blood volume
stretch of right atrium
secretion of ANP