Dr. Zarin Kauser discusses electrolyte balance and regulation. Electrolytes like sodium, potassium, chloride, and calcium ions play important roles in maintaining fluid balance. Their concentrations are precisely regulated through hormones like aldosterone and ADH, which regulate sodium and water retention and excretion. The renin-angiotensin system also helps regulate electrolyte balance and blood pressure by stimulating sodium retention or excretion. Precise balance of electrolytes and fluid volumes is critical for normal cell and organ function.

1. DR ZARIN KAUSER
ASSISTANT PROFESSOR
KAMSRC
ELECTROLYTE BALANCE
AND REGULATION

5. MOVEMEMENT OF SOLUTES

15. ELECTROLYTE BALANCE
•Electrolytes are the compounds which readily
dissociate in solution and exist as ions i.e.,
positively and negatively charged particles.
• The electrolytes are expressed as
milliequivalents (mEq/L) rather than milligrams.
•The most important electrolytes include Na+, K+,
Cl-, Ca2+, and HPO4.

16. ELECTROLYTES CONCENTRATIONS

19. •Movement of water across the biological membrane
depends of the OSMOTIC PRESSURE.
•OSMOTIC PRESSURE :- difference between
intracellular fluid (ICF) and extracellular fluid (ECF)
•In healthy state :
the osmotic pressure of ECF -->due to Na ions, is
equal to the osmotic pressure of ICF which is
predominantly due to K ions.
• There is no net passage of water molecules IN or
OUT of the cells, due to this osmotic equilibrium.
OSMOTIC PRESSURE

20. OSMOLARITY , OSMOLALITY OF BODY FLUIDS
1) OSMOLARITY :- The No. of Moles (or millimoles) per
liter of SOLUTION.
2) OSMOLALITY :- The No. of Moles (or millimoles) per
kg of SOLVENT.
If the solvent is pure water, there is almost no difference
between OSMOLALITY and OSMOLARITY.
For BIOLOGICAL FLUIDS--> Osmolality (commonly used)

21. •RANGES--> 285-295 milliosmoles/kg
• Sodium and its anions --> largest contribution
• Measured by--> “OSMOMETER”
• Can be computed from the concentrations (mmol/
of Na , K , urea and Glucose
as follows :-
2(Na ) + 2(K ) + Urea + Glucose.
• The factor 2 is used for Na and K ions to account
for the associated anion concentration.
Osmolality Of Plasma

22. OSMOLALITY OF PLASMA
The difference in measured osmolality and
calculated osmolality is called Osmolar Gap.

23. • Since, plasma Na -->is predominant
•Plasma osmolality = 2 x plasma Na
(mmol/kg) (mmol/L)
•Above calculation holds good--> if Plasma
concentration of glucose and urea are in
Normal Range.
•Severe hyperproteinemia and lipemia
present calculation not valid.

24. REGULATION OF ELECTROLYTE
BALANCE
MAJOR REGULATORY FACTORS ARE :-
•Hormones ( Aldosterone, ADH )
•Renin-Angiotensin system
•Atrial Natriuretic Peptide (ANP)

25. ALDOSTERONE
ALDOSTERONE ( mineralocorticoid, Zona
Glomerulosa of adrenal cortex )
Na+– K+ exchange( Na+ reabsorption) and Na+ –
H+ exchange at the Renal Tubules.
Net effect is SODIUM RETENTION.
Regulates

26. Anti–Diuretic Hormone (ADH)
When Plasma Osmolality increases(due to Na)
Osmoreceptors of Hypothalamus are
stimulated
ADH secretion
Resulting in
Increases water reabsorption by the renal
tubules

27. Renin-Angiotensin System
When ECF volume falls
Renal plasma flow decreases
Leads to
Release of RENIN by juxtaglomerular
cells

29. FACTORS WHICH
STIMULATE THE
RENIN RELEASE
INHIBITS THE RENIN
RELEASE
Decreased BP
Salt depletion
Prostaglandins
Increased BP
Salt intake
Prostaglandin
inhibitors
Angiotensin - II

30. CLINICAL SIGNIFICANCE
•ACE (Angiotensin Converting Enzyme)-->is a
glycoprotein.
• ACE inhibitors is useful in treating EDEMA &
CHRONIC CONGESTIVE CARDIAC FAILURE.

31. Atrial Natriuretic Peptide (ANP)