Summary
Summary Calcium homeostasis
- Course
- Institution
Neurophysiology, synaptic pharmacology and endocrinology - 2nd semester Includes bullet points, key diagrams and images
[Show more]
Seller
Follow
alexd1
Content preview
Calcium Homeostasis Low calcium increases sodium permeability and vice versa
Hypocalcaemia- increases muscle/nerve excitability causing spasms
Hypercalcaemia- decreases muscle/nerve excitability so can cause arrhythmias
Bones and teeth act as calcium reservoirs
Bone has crystalline hydroxyapatite which precipitates around collagen extra-
cellular matrix
High levels of calcium in bone fluid
Osteoblasts- deposit bone and secrete collagen matrix
Osteoclasts- bone resorption where enzymes and HCl dissolve bone
Parathyroid
Parathyroid hormone secretion increases when plasma levels of calcium are low
and acts to increase them
Parathyroid cells have calcium sensing receptors (GPCRs)
PTH acts on bone, kidneys and GIT
Causes calcium release from bone breakdown which increases levels in the
plasma
Fast Exchange
PTH causes rapid efflux of calcium from bone fluid
PTH receptors on osteoclasts and osteoblasts (GPCRs) which increase cAMP
Increased cAMP causes calcium to move from the bones fluid and into cells
Osteoblasts and osteocytes have gap junctions allowing calcium to move through
the osteocytes to the osteoblasts and into the plasma
Slow Exchange
Activated by prolonged hypocalcaemia
PTH causes osteoclasts to increase bone resorption to increase calcium plasma
conc
Osteoblasts activity is inhibited
Phosphate levels are also increased
Calcium levels are restored when dietary levels increase
PTH causes cavities in bone causing weakness
PTH Effect on Kidneys
PTH promotes calcium retention so reabsorption
Promotes phosphate excretion decrease calcium reabsorption
Activates vitamin D which increase calcium absorption in the GIT
Calcitonin
Antagonist to PTH
Secreted by C cells in the thyroid
Secretion increases when calcium plasma levels are high
Acts to decrease plasma levels
Inhibits reabsorption of calcium and phosphate in the kidney
Decreases bone resorption so inhibits osteoclasts activity
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller alexd1. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.89. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75759 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now