Hormon Parathyroid Dr. Nanang Miftah F, SpPD Bagian Endokrin dan Metabolik FK UNLAM- RS ULIN
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Hormon Parathyroid
Dr. Nanang Miftah F, SpPD
Bagian Endokrin dan MetabolikFK UNLAM- RS ULIN
Kelenjar Parathyroid
A. Gross anatomy 1. Terdiri dari 4
bagian kelenjar paratiroid
2. Terletak di belakang kelenjar thyroid
Parathyroid glandsMicroscopic anatomy
Parathyroid glands1. oxyphil cells a. larger, polygonal cells b. unknown function
2. chief cell a. pale, acidophilic cytoplasm
b. secretes parathyroid hormone c. incr. blood Ca++ levels
5
Fungsi Kelenjar Parathyroid(parathyroid hormone or “parathormone”)
• Meningkatkan Kadar Ca++ (calcium) dalam darah• Mekanisme Pengaturan Kalsium oleh PTH
1. Menstimulasi osteoklas untuk melepas kalsium dari tulang
2. Menurunkan sekresi Ca++ pada ginjal3. Mengaktifkan Vitamin D meningkatkan absorbsi Ca di
usus halus• Fungsinya berlawanan dengan hormon kalsitonin,
PTH release:1) stimulates osteoclasts2) enhances reabsorption of Ca++ by kidneys3) increases absorption of Ca++ by intestinal mucosal cells
Hyperparathyroidism- too much Ca++ drawn out of bone; could be due to tumor
Hypoparathyroidism- most often follow parathyroid gland trauma or after removal of thyroid--- tetany, muscle twitches, convulsions; if untreatedrespiratory paralysis and death
Parathyroid
Target Action
Parathyroid(PTH)
BoneKidneyGI Tract
Calcium
Calcium Homeostasis• Parathyroid
– most important endocrine regulator of calcium and phosphorus concentration in extracellular fluid (PTH)
– Targets receptors on bones and kidneys
• Calcitonin– C cells of Thyroid– Decreases mobilization
and uptake of calcium
Study Figure 9.45
Feedback Loop• Negative feedback in calcium
homeostasis. A rise in blood Ca2+ causes release of calcitonin from the thyroid gland, promoting Ca2+ deposition in bone and reducing reabsorption in kidneys.
• A drop in blood Ca2+ causes the parathyroid gland to produce parathyroid hormone (PTH), stimulating the release of Ca2+ from bone.
• PTH also promotes reabsorption of Ca2+ in kidneys and uptake of Ca2+ in intestines.
Calcium Homeostasis
Parathyroid “C” Cells
PTH Calcitonin
BoneKidney
Intestine
BoneKidney
[Ca++] [Ca++]
Stim
ulat
e Stimulate
Inhi
bit
Inhi
bit
In plasma In plasma
Calcium Homeostasis
Parathyroid Homeostatic Imbalances
Hiperparathyroid• Kadar calsium dalam
darah <<<• - ca >>• Terjadi Penumpukan
kalsium pada :– Ginjal– Gigi– Otot
Hipoparatiroid
• Kalsium dalam darah <<
• Neuron hiperaktiv• Tetani spasme