Calcium Physiology Flashcards
Calcium:
Where is calcium absorbed?
Where is it filtered and reabsorbed?
Small intestine
The kidneys
PTH:
What does it stand for?
How may PT glands are there?
How does it sense calcium levels?
3 things happen when it is released:
- What do the kidneys do?
- What happens at the bones?
- What does the kidney increase the synthesis of?
Parathyroid hormone
4 glands - can be 6 in some - look up
Via calcium-sensing receptor (CaSR)
Increased osteoclast activity (increases resorption)
Increased kidney reabsorption
Increased kidney calcitriol synthesis
Vitamin D3 (cholecalciferol):
Where is 90% of it made from?
It is hydroxylated via the liver into what?
It is also hydroxylated via the kidneys into its active form? What is it then called?
What upregulates the hydroxylation in the kidneys?
Calcitriol:
- What ions does it increase the levels of?
- What 2 mechanisms does it use to increase this?
Steroid synthesised in the skin (via sunlight)
25-hydroxyvitamin D3 - this is what is usually detected in a blood test
1,25-dihydroxyvitamin D3
PTH
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Calcium and phosphate
Increased intestinal absorption
PTH activity
Calcitonin (has minor effects):
Where are they released from?
How does it reduce calcium levels? - 2
What hormone does it, therefore, work against?
C-cells of the thyroid gland
Reduces osteoclast activity
Increased kidney excretion
PTH
Bone:
What cells build bone resulting in lower calcium levels in the plasma?
What cells break down bone resulting in higher calcium levels in the plasma?
Osteo(b)lasts - (B)uild (B)one
Osteoclasts
Phosphate:
Phosphate and calcium levels are tightly controlled via the kidneys.
What is important to remember about their relationship?
A change in one causes the opposite change in the other
Albumin:
What percentage of calcium is bound to albumin?
What does corrected calcium levels mean then?
Around 40%
The albumin calcium levels are included as well as serum calcium levels.
