Week 8: Ca2+, Mg2+, and PO4- handling Flashcards
Functions of intracellular [Ca2+]
- second messenger
- Muscle contractility
- Cell motility
Extracellular Ca2+ functions
- Excitation-contraction coupling in muscle
- Synaptic transmission
- Platelet function & coagulation
- Primary regulator of PTH secretion
Why are Ca2+ levels so tightly regulated
because it can effect the potentials of excitable cells
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issue with Hypocalcemia and excitable cells
Spontaneous depolarization
Issue with hypercalcemia on excitable cells
Depolarization hurdle
Where is most of the Ca2+ in the body
99% of total body Ca2+ and 85% Phosphate contained within the skeleton (hydroxyapatite)
How does Ca2+ circulate
46% bound to albumin
6% bound to small anions (citrate, phosphate, lactate)
48% biologically free active Ca2+ in feedback loops
How is rapid release of Ca2+/Pi mediated
mediated by PTH and Vitamin D acting directly on osteoblasts and indirectly on osteoclasts to resorb the bone
Describe Ca2+ flux between body compartments
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Describe the effect of pH, plasma protein & citrate on total & free Ca2+
corrected or adjusted total Ca2+
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Describe the bone remodeling process
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What happens when too much bone is resorbed?
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Ca2+/Pi maintenance
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Where are the PT glands located?
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Transfusions and Ca2+
preservative is citrate and adding a lot of citrate to someone can soak up a person’s Ca2+
Overview of Ca/P maintenance
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Describe PTH synthesis and Secretion
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Describe how Ca2+ is sensed by the PT glands
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Describe other factors regarding PTH secretion
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How is PTH gene transcription regulated?
Calcitriol inhibits PTH gene transcription
Low plasma Mg2+ effects on PTH
stimulates secretion of PTH
High plasma Mg2+ effects on PTH
Inhibits secretion of PTH
Mg2+ depletion effects on PTH
Paralyzes secretion
(Mg2+ second messenger in relay from CaSR to PTH secretion ( ie hypocalcemia in neonates with diarrheal disease)
Describe PTH metabolism
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Describe PTH clearance
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Describe PTH action in the kidney
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Describe PTH action in bone
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Describe RANKRANKL action
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PTH action in bone additional
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PTHrP AKA
PArathyroid hormone related peptide
PTHrP functions
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Describe Pi features
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How is plasma [Pi] regulated
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Etiologies of hypocalcemia
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Etiologies of hypercalcemia
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Etiologies of hyppphosphatemia
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Etiologies of Hyperphosphatemia
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Consequences of hypocalcemia
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Consequences of hypercalcemia
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Consequences of hypophosphatemia
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Consequences of hyperphosphatemia
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Primary hyperparathyroidism vs hypercalcemia of malignancy vs hypoparathyroidism
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Review of Vitamin D3
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Describe Calcitriol synthesis
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Describe Calcitriol targets and activity
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Describe Calcitriol MOA
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Describe the general action of nuclear steroid receptors
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Describe VDR expression
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What genes are regulated by Calcitriol
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How is calcitriol regulated?
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Describe 24-hydroxylase deficiency
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What is Calcitonin?
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Normocalcemia
absorption = secretion
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Hypocalcemia
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Hypercalcemia
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Describe the regulation of Plasma {Mg2+]
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