QS Study

Distribution of Calcium (Ca+) of Plasma

The calcium in the blood is vital for a number of functions, including blood clotting, diffusion of nerve impulses, muscle contraction, the constancy of cell membranes, and cell metabolism.

Name the hormone regulating the blood Ca+ level.

The body of a young adult human contains 27.5 mol of Ca 99% of Ca2+ is in the skeleton.

Distribution of Ca2+

Calcium is the most abundant mineral in the human body, is involved in many physiological and pathological processes. Calcium is maintained within a fairly narrow range from 8.5 to 10.5 mg/dl (4.3 to 5.3 mEq/L or 2.2 to 2.7 mmol/L).

Normal plasma conc. of Ca++ = 10 mg/dl (2.5 mmol/L, 5 mEQ/ L)

Range: 9 – 12 mg/dl.

Fig: Distribution of Calcium (Ca+) of Plasma


In humans, when the plasma calcium level rises above its set point, the thyroid gland releases calcitonin, causing the plasma calcium level to return to normal. When it falls below that set point, the parathyroid glands release parathyroid hormone (PTH), causing the plasma calcium level to rise.

Table: Distribution (mmol/L) of calcium in the normal human body.

Hormone regulate the blood Ca2+ level

  1. Parathyroid hormone,
  2. Calcitonin hormone,

Besides, 1, 25 – Dihydroxycholecalciferol (a steroid hormone from Vit.) and Parathormone related protein (PTHrP) also responsible for maintaining optimum blood Ca2+ level.