calcium and phosphate balance

Question 1

regulation of parathyroid hormone and calcium

Answer 1

• if parathyroid cell sense increase calcium in blood, it has downregulates PTH release
• Vitamin D also downregulates PTH release
• if parathyroid cell sense decrease calcium in blood, it has upregulation PTH release
• if parathyroid cell sense decrease phosphate in blood, it has upregulates PTH release

Question 2

anatomy of parathyroid gland

Answer 2

The parathyroid glands are pea-sized glands located at the top and bottom posterior borders of the lateral lobes of the thyroid gland.

Question 3

Functional anatomy of parathyroid gland

Answer 3

• thyroid parathyroid glands: connective tissue capsule of thryroid gland
• connective tissue capsule seperating thyroid and parathyroid glansa
• richly vascularized and consist primarily of chief cells

Question 4

Parathyroid Hormone Biosynthesis and Transport

Answer 4

PTH is synthesized as a prepropeptide- rapidly cleaved to yield proPTH and then the mature form of PTH (84 amino acids).

PTH synthesis and release is continuous, 6–7 superimposed pulses each hour.

PTH is degraded by the kidney and the liver
aminoterminal fragments 10% of circulating PTH fragments- biologically active but have a short halflife of 4-20 minutes
carboxyterminal fragments 80% of the circulating PTH fragments no biologic activity and have a longer halflife;

Intact PTH hormone accounts for 10% of the circulating PTHrelated peptides.
determination of the intact molecule is the only reliable index of PTH
levels.