paratthyroid.pptx

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