Table of Values

Fig 1 shows how fluid is exchanged between the extracellular fluid (ECF) and intracellular fluid (ICF).

The values for the volumes and composition of cellular fluids are as follows:

Chart 1 How the 42 litres of body water is distributed
Table 1 Daily requirements of a normal adult
Table 2 Composition of body fluids
Table 3 Composition of stomach and small bowel secretions

Fig 1 Passage of water and ions through different fluid compartments

Chart 1 How the 42 litres of body water is distributed

	Daily requirement
Water	2.5-3 litres
Na⁺	140-160 mmol
K⁺	80-100 mmol

Table 1 Daily requirements, normal adult

	ECF (ions in mmol/L)	ICF (ions in mmol/L)
Na⁺	145	12
K⁺	5	150
Ca²⁺	2.5	0.001
Cl^-	105	5
HCO₃^-	25	12
pH	7.4	7.1

Table 2 Composition of body fluids

	Stomach (low secretion rate)	Stomach (high secretion rate)	Small bowel
Na⁺	90 mmol/L	10 mmol/L	130 mmol/L
K⁺	10 mmol/L	20 mmol/L	5 mmol/L
Cl^-	125 mmol/L	155 mmol/L	110 mmol/L
HCO₃^-	-	-	30 mmol/L
H⁺	20 mmol/L	125 mmol/L	30 mmol/L
Daily volume produced	2 litres	2 litres	1.5 litres

Table 3 Composition of stomach and small bowel secreations

Ionic composition depends on rate of gastric secretion; sodium production falls and hydrogen ion secretion rises greatly on increasing secretion rate from 0.5-2.5 ml/min.