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PARATHYROID GLAND PATHOPHYSIOLOGY Yousaf khan Lecturer Renal Dialysis Technology PARATHYROID GLANDS The parathyroid gland is located in the neck Four glands located on the posterior surface of the thyroid gland Derived from the 3rd and 4th pharangeal pouches The parathyroid produces a hormone called PTH. Location of Parathyroid Glands The Basics Parathyroid hormones is the most important Endocrine regulator of calcium and phosphorus concentration in extra cellular fluid. How does the hormones produced maintain homeostasis? Like all endocrine glands, parathyroid’s makes a hormone, parathyroid hormone (PTH) has a very powerful influence on the cells of the bones which causes them to release their calcium into the blood stream. Function of Parathyroid Hormone Parathyroid hormone regulates calcium, phosphorous, magnesium balance within the blood and bone by maintaining a balance between the mineral levels in the blood and the bone. TARGET ORGANS FOR PTH G.I.T Bone Kidney Lactating Mammary Glands Action on GIT PTH increase Ca++ absorption from intestinal mucosa Increase formation of 1, 25dihydroxycholecalciferol from Vitamin D3, which increase absorption by: Increase formation of calcium binding protein Increase formation of calcium stimulant ATPase Increase formation of alkaline phosphatase, it also increase phosphorus absorption from GIT. Action of Bone Increase absorption of Calcium from bone into the blood in the following ways. Activation of all osteoclasts Rapid formation of osteoclasts from mesenchymal stem cells Delay in conversion of osteocytes into osteoblasts. Action on Kidneys Increase renal tubular reabsorption of calcium Increase reabsorption of Mg and H Decreased phosphate, sodium and bicarbonate reabsorption from the proximal tubule Increased proximal tubule 1-alphahydroxalase activity Action on lactating mammary glands Reduces excretion of calcium in milk Control of PTH secretion a. b. c. PTH is not control by Pituitary Gland or any other nervous factor, but controlled by blood calcium level. Low calcium level of blood increases PTH secretion High plasma phosphate level promotes PTH secretion Rise in plasma Mg level lowers PTH secretion CALCITONIN Polypeptide hormone Synthesized and secreted by the parafollicular C-cells of the thyroid gland ACTIONS OF CALCITONIN ON BONE Decresaed osteoclastic number Decreased osteoclastic activity Actions are proportional to baseline rate of bone turnover Hypoparathyroidism Parathyroid gland secretes decrease amount of PTH. Causes: Surgical ( thyroidectomy) Anatomical ( Malformation ) Digeorge syndrom ( failure in the development of the third and forth branchial pouches) Idiopathic Infection necrosis a. b. c. d. e. f. Signs and symptoms Hypocalcemia: low level of calcium in blood but increase blood phosphrous level. Increase excitability of CNS and peripheral nerves. These effects and hypocalcemia lead to Tetnay. Tetnay: a condition of intermittent muscular spasms, caused by parathyroid malfunction and consequent calcium deficency. Hyperparathyroidism PTH secrete increase amount of Parathyroid hormone. Charachterized by hypercalcemia, it may three type Primary type Secondary type Tertiary type Causes: a. Hyperplasia of all PT gland b. Localized tumor SIGNS AND SYMPTOMS Demineralization of bones Deformation of bone Muscular weakness Constipation Abdominal pain Peptic ulcer Nausea Vomiting Joint pains and arthritis Thank you