2. Learning Objectives Dietary sources Daily Requirements Metabolism
Important functions and
Deficiency diseases

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

4. The body needs a small amount of sodium to help maintain normal blood pressure and normal function of muscles and nerves.

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

6. 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

7. 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.

8. Dietary sources Bread Cheese salad egg nuts spinach whole grain
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

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

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

11. Adults maintain sodium balance with little more than What is required by infant.
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.

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

13. Distribution 1/3rd of Na is in inorganic portion of skeleton
2/3rd in ECF and is osmoticaly active
(water soluble and exchangeable)

14. Contd.
Total body content = 3800 – 4000 meqt (165 – 174 mg)
ECF = 1750 meqt (76 mg)
Soft tissues = 400 meqt (17.4 mg)
Bone = 1850 meqt (80 mg)

15. 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)

16. Functions Major cation of ECF
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.

17. Ions Contributing to Resting Potential
Sodium (Na+)
Chloride (Cl-)
Potassium (K+)
Negatively charged proteins (A-)
synthesized within the neuron
found primarily within the neuron

18. The Neuron at Rest
Ions move in and out through ion-specific channels
K+ and Cl- pass readily
Little movement of Na+
A- don’t move at all, trapped inside

19. 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

20. 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.

21. 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.

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

23. 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

24. 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.

25. Neural Conduction and Synaptic Transmission
How Neurons Send and Receive Signals

26. The Neuron’s Resting Membrane Potential
Inside of the neuron is negative with respect to the outside
Resting membrane potential is about -70mV
Membrane is polarized, it carries a charge
Why?

27. Ionic Basis of the Resting Potential
Ions, charged particles, are unevenly distributed
Factors influencing ion distribution
Homogenizing
Factors contributing to uneven distribution

28. Ionic Basis of the Resting Potential
Homogenizing
Random motion – particles tend to move down their concentration gradient
Electrostatic pressure – like repels opposites attract
Factors contributing to uneven distribution
Membrane is selectively permeable
Sodium-potassium pumps

29. Equilibrium Potential
The potential at which there is no net movement of an ion – the potential it will move to achieve when allowed to move freely
Na+ = 120mV
K+ = -90mV
Cl- = -70mV (same as resting potential)

30. The Neuron at Rest
Na+ is driven in by both electrostatic forces and its concentration gradient
K+ is driven in by electrostatic forces and out by its concentration gradient
Cl- is at equilibrium
Sodium-potassium pump – active force that exchanges 3 Na+ inside for 2 K+ outside