PTH 01

1. Diffusible Non-diffusible
Ca2+ concentration in ECF
(bood and interstitium)
• Free Ca2+ (50%)
• Action
potentials
• Contraction
muscles
• Hormon
secretion
• Blood
coagulation
• Ca2+ linked with
oxalate/phospate
• Electricallyneutral
• Not useful for
celluarprocesses
• Ca2+ bound
protein (40%)
• Albumin
• Large
• Charged
• Unenvolved in
cellular
processes

3. • Low • High
Ca2+ level
PTH Vitamin Dcalcitonin
2.25 - 2.75 mmol/L
phosphateconcentrationin plasma
0.8 - 1.6 mmol/L

4. This PhotobyUnknown author is licensedunderCC
BY-NC.
• Oestrogens
• Androgens
• Thyroxin(T4)
• Triiodothyronine(3)
• Modify bones
• resorption
bones
• Glucocorticoids

5. Parathyroid glands and parathyroid hormone

7. Chief cell

8. Parathyroid hormone
• Increases
• plasma concentrationof calcium
• Decreases
• plasma concentrationof
phosphate

9. Parathyroid hormone & plasma Ca
concentration
• PTH
• Stimulates
• bone resorption to mobilise
• (slower)
• Decreases
• calcium excretion in the urine
• Increasing reabsorptionin the
distal nephron
• (faster)

10. Parathyroid hormone & plasma Ca
concentration
• PTH
• Induce
• fast release of calcium and
phosphate from the bone
fluids
• Increases
• calcium and phosphate
absorptionin the small
intestine

11. Parathyroid hormone & plasma Ca
concentration
• PTH
• Blocks
• Na/Pi cotransporterin the
proximal tubule
• leads to the increased
phosphate excretion in the
urine
• leads to decrease of
phosphate concentrationin
plasma

12. Parathyroid hormone & plasma Ca
concentration
• Na/Pi cotransporterblocking is
• compensationof increased
phosphate
• resorption from bones
• absorptionfrom the small
intestine

13. Parathyroid hormone secretion
• is regulated by
• the levels of calcium ions in the
plasma
• simple negative feedback regulation

14. G-protein-coupled
receptors
Chief cell