Fluid balance and electrolyte distribution in human body.

Calcium (Ca 2+ )
– Most abundant ion in body
• plasma 2.3-2.6 mmol/L
• most stored in bone (98%) as hydroxyapatite
- Necessary for structure of bones and teeth, blood clotting, hormone
secretion, and cell receptor function
- Regulation:
• Parathyroid Hormone (PTH) - ↑ blood Ca 2+
• Calcitonin (CT) - ↓ blood Ca 2+
- Homeostatic imbalances:
Hypocalcemia (necrotic pancreatitis, malabsorption, hypoparathyreosis,
vitamin D deficit (osteomalacia)) - muscle cramps, convulsions
Therapy: 1. cause, 2. 10% Ca-gluconicum (10ml ampules, 1ml =
0.25mmol)
Hypercalcemia (hyperparathyreosis, hypervitaminosis D, osteolytic tumor
metastasis)- vomiting, cardiovascular symptoms, coma (critical [Ca+] is
above 3.75 mmol/l); prolonged abnormal calcium deposition, e.g.,
stone formation
Therapy: 1.cause, 2. increase of diuresis by furosemide (at 3L/day),
glucocorticoids decreasing Ca+ absorption by intestine, calcitonin
Phosphate (H 2 PO 4- , HPO 4
2-
, PO 4
3-
)
– Important ICF anions; plasma 0.7-1.5 mmol/L
• most (85%) is stored in bone as calcium salts
• also combined with lipids, proteins, carbohydrates, nucleic acids
(DNA and RNA), and high energy phosphate transport compound
• important acid-base buffer in body fluids
– Regulation - regulated in an inverse relationship with Ca 2+ by PTH and
calcitonin and Vitamin D (If the concentration of one increases, that of
the other decreases)
– Parathyroid hormone (PTH) - Increases plasma calcium levels
– Vitamin D (fat-soluble steroid) - Increases calcium absorption from the
GI tract
– Calcitonin - Decreases plasma calcium levels
– Homeostatic imbalances
• Phosphate concentrations shift oppositely from calcium
concentrations and symptoms are usually due to the related
calcium excess or deficit