LMP301H1 Lecture Notes - Lecture 15: Bone Pain, Autocrine Signalling, Hypocalcaemia

65 views3 pages
14 Sep 2016
School
Course
Professor
LMP301
Introduction to the Biochemistry of Human Disease
Lecture 15 Calcium
Homeostasis
o Net gain at intestine = net loss at kidney (150 mg/d)
o No net change at bone formation/resorption (500 mg/d)
Hormones
o PTH
Produced by the parathyroid glands behind the thyroid
Stimulated by low serum Ca2+ and inhibited by high Ca2+
Bone: bone resorption
Kidney: Ca2+ reabsorption, PO4- reabsorption
Stimulate 1,25 (OH)2 vitD
o 1,25 (OH)2 vitD
Plants: from vitD2; Animals: from vitD3
ProvitD3 vitD3 25-OH D3 1,25(OH)2D3 (active)
Side products: 24,25(OH)2D3 and 1,24,25(OH)3D3 (inactive)
1st step: UV
2nd step: 25-hydroxylase (liver)
3rd step: 1α-hydroxylase (kidney, pancreas, etc.)
Inactivation: 24-hydroxylase
Autocrine: regulation of cell growth
Paracrine: immune modulation
Endocrine: calcium homeostasis, muscle and bone health
Intestine: Ca2+ and PO4- absorption
Bone: ↑ bone resorption
Feedback: inhibit PTH
Bound to vitD-binding protein in circulation and targets nuclear vitD
receptor
o Calcitonin
From the parafollicular/C cells of the thyroid
Stimulated by high Ca2+, gastrin, and pentagastrin
Inhibit bone resorption by osteoclasts and Ca2+ and PO4- (clinically
insignificant)
Treatment of osteoporosis
Marker of medullary thyroid carcinoma (C cells)
Bone
o Osteoclasts (resorption) and osteoblasts (formation)
Resorption markers: deoxypyridinoline
Formation markers: alkaline phosphatase, osteocalcin
Diseases
Name
Causes
Characteristics
Diagnosis
Treatments
Hypocalcemia
Idiopathic
Post-surgical
Pseudohypoparathyroidism
Neuro-
hyperexcitability
(tetany,
serum Ca2+
Unlock document

This preview shows page 1 of the document.
Unlock all 3 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
Monthly
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.