2. Sodium Natrium Na At.No. 11 Atomic mass 22.98

3. SODIUM Alkali metal Highly reactive,
Found in combined state, mostly as Salt.

4. Electrolyte Balance

5. Electrolyte Balance
Electrolytes are a major component of body fluids. They enter the body in the food we eat and the beverages we drink.
Electrolytes leave the body mainly through the kidneys by way of the urine, they also leave through the skin and feces.
Severe vomiting and diarrhea can cause a loss of both water and electrolytes from the body, resulting in both water and electrolyte imbalances.

6. Electrolyte Balance
The concentrations of electrolytes in body fluids must be maintained within specific limits, and even a small deviation outside these limits can have serious or life-threatening consequences.
Three most clinically significant electrolytes are sodium ions, potassium ions, and calcium ions.

7. Fluid Movement Across the Cell Membrane
One of the important functions of electrolytes, particularly sodium, is to control fluid movement between fluid compartments.
The movement of fluid across the cell membrane differs from the movement of fluid between the interstitial compartment and plasma.

8. Sodium/Potassium Ion Pump
The cell membrane acts as a barrier to separate intracellular and interstitial fluid compartments.
Electrolytes move across the cell membrane through channels and ion pumps that are selective for specific ions.
The sodium/potassium ion pump actively transports sodium and potassium.

9. Sodium/Potassium Ion Pump
Ion pumps in the membrane help ions to move against their concentration gradient from an area of lower concentration to an area of higher concentration.
These pumps require an input of energy in the form of ATP.

10. Sodium Ion Channel
Channels specific for sodium ions allow these ions to diffuse from areas of higher to areas of lower concentration.
In most cells the sodium channels don't allow sodium ions to move across the membrane very quickly.

11. Fluid Movement: Potassium Ion Channel
The channels specific for potassium ions allow these ions to move across the membrane fairly quickly from areas of higher to areas of lower concentration.
Differences in ion concentration between intracellular and interstitial fluids are caused by these selective ion channels and ion pumps in the cell membrane.
These differences make the membrane potential possible and they facilitate a number of important physiological processes.

12. Fluid Movement: Water
The cell membrane is freely permeable to water, which moves from the area of higher water concentration to lower water concentration.

13. Dietary sources In all foods even water.
Table salt “NaCl”, added to food Bread, Cheese, salad, egg, nuts, spinach whole grain
In all foods even water.
2.5 grams of salt contain 1gm of Na

14. REQUIREMENT Estimated safe and adequate daily dietary intake
Infants 0 – 0.5 yrs 115 – 350mg
0.5 – 1.0yr – 750mg
Children 1 – 3 yrs 325 – 975
4 – 6 yrs 450 – 1350
7 – 10 yrs 600 – 1800
– 2700
Adults – 3300

15. Infants requirement is low because of
Small lean body mass
Composition of feces
Cutaneous losses
Minimum requirement for infants and young children
is about 58 mg/day.

16. Human milk contains about 160mg/litre Cows milk contains about 483mg/litre

17. Absorption and Metabolism
Sodium is readily absorbed from ileum
Very little is excreted in feces except in diarrhea

18. Sweat is another major route of Sodium loss
20-50mg/L

19. Adults maintain sodium balance with very little intake
Kidneys maintain its balance in blood (Homeostasis) under the influence of a hormone “Aldosterone” on renal tubules.
When intake is decreased, aldosterone secretion Increases resulting in decrease of urinary excretion of sodium.

20. Distribution in the body
Total body content = 3800 – 4000 meqt (165 – 174 mg)
44 % is in ECF = 1750 meqt (76 mg)
(osmoticaly active, water soluble and exchangeable)
10 % is Soft tissues = 400 meqt (17.4 mg)
46 % is in Bone = 1850 meqt (80 mg)

21. Distribution in body / tissue
Whole blood = 70 meqt/L (161 mg/dl)
Plasma = 143 meqt/L (330 mg/dl)
Cells = 37 meqt/L (85 mg/dl)
Muscle tissue = 26 – 70 meqt/L (60 – 160 mg/dl)
Nerve tissue = ~ 140 meqt/L (312 mg/dl)

22. Functions As a major cation of ECF
It regulates Acid base balance, in conjunction with Cl / HCO3
It maintains the osmotic pressure of body fluids and protects severe fluid loss from body.
It preserves normal irritability of muscle and permeability of cells.

23. Deficiency Diseases or Symptom
When on normal diet  No hyponatermia
Normal range in plasma is 135 – 145 meqt/L
Hyponatermia is mostly secondary to
Injury
Illness (G/E)
Burns
Use of diuretics

24. Deficiency Diseases or Symptom
Adrencorcortical insufficiency (Addison’s disease)
Chronic Renal disease resulting in poor re-absorption of sodium
Cirrhosis / CCF –  serum sodium level, without reduction in total body content of Na.

25. fall in tonicity as well as total volume of plasma Leading to
Severe deficiency results in
fall in tonicity as well as total volume of plasma
Leading to
Muscular cramps  Extremities and abdomen
Headache
Nausea
Dry skin
Reduce sweating
Low urine out put having high specific gravity.

26. These are the conditions When Kidneys respond
Complete re-absorption of filtered sodium
Sodium excretion may fall to 20 meqt. / day or less.

27. Serum Sodium and adrenocortical function:
Hypo-adrenalism 113 meq/L
(Addison’s disease)
Hyper-adrenalism 150 meq/L
(Cushing syndrome)
Normal 135 – 145 meq/L

28. Toxicity Diseases or Symptoms
Hyper natremia may occur as a result of
Rapid administration of sodium salt
Hyper active adrenal cortex
Administration of Cortisone or deoxy cortisone
Dehydration excessive loss of water (Diabetes insipidus)
May cause rise in blood pressure in susceptible individually.

29. Hypernatremia
Let’s consider what will happen if the sodium concentration of the blood plasma increases?.
What effect would this increase in sodium concentration have on the cells that are bathed by the interstitial fluid?
___ Cells swell
___ Cells shrink

30. Sodium Homeostasis
The normal concentration range of sodium in the plasma is milliequivalents per liter, making sodium the ion with the most significant osmotic effect in the extracellular fluid.

31. Hyponatremia
What effect would this decrease in sodium concentration have on the cells that are bathed by the interstitial fluid?
___ Cells swell
___ Cells shrink

32. Roles of Sodium in the Body
In addition to playing a pivotal role in nerve impulse conduction and muscle contraction, as the major extra cellular positive ion, sodium is the primary regulator of water movement in the body because water follows sodium by osmosis.
If sodium levels in the plasma change, those changes determine fluid levels in the other compartments.

33. Renin-Angiotensin System
angiotensinogen
renin
angiotensin I
converting enzyme
angiotensin II
efferent constriction;
PT reabsorption
vasoconstriction
aldosterone; CD reabsorption