Flashcards in Regulation Of Ca And PO4 Metabolism Deck (33)
Loading flashcards...
1
Calcium distribution in the body
ECF
Plasma
ICF
Bones and teeth
.1% ECF
.5% plasma
1% ICF
99% bones and teeth
2
In the plasma, Ca exists in _____ form complexed to anions or ____ form bound to plasma proteins
Non-ionized form complexed to anions
Ionized form bound to plasma proteins
3
Ways to alter the concentration of Ca in the plasma
1. Alter total Ca - changes in plasma protein concentration alter total C concentration
2. Alter anion concentration
3. Alter Ca fraction bound to proteins
4
What plasma protein binds Ca in the serum
Albumin
5
In acedimia, albumin preferentially binds _____, thereby increasing ionized _____ in the serum
Albumin will bind H+ so more Ca is ionized
6
In alkalemia, albumin prefferentially binds _____, thereby decreasing the concentration of ionized _____ in the serum
Preferentially binds Ca so will decrease the concentration of ionized Ca
7
______calcemia increases neuromuscular excitability leading to tetany/spasticity
Hypocalcemia
8
_____calcemia depresses neuromuscular excitability by what mechanism
Hypercalcemia shifts the threshold away from membrane potention
9
Regulators of plasma calcium concentration
PTH
Calcitonin
Calcitriol
10
Causes of low serum calcium
Hypoparathyrroidism
Renal disease
Vitamin d deficiency
11
Organs invovled in the regulation of Ca
Bone
Kidney
Intestines
With three hormones
PTH
Calcitriol
Calcitonin
12
Extracellular concentration is _______ correlated to that of Ca
EC concentration of Pi is regulated by the same hormones as Ca
Inversely correlated to Ca 2+
13
Regulators of phosphate metabolism
Diet
Calcitriol increases plasma
PTH increases plasma []
Renal tubular resorption
14
FGF23 is derived from
Bone
15
Factors that regulate fgf23
Phosphate and VitD
16
Effects of FGF-23
Directly downregulates NaPi transporters in kidney
Stimulates PTH to downregulate NaPi transporters in kidney
Decreases calcitriol production in the kidney
17
FGF23 is secreted from the bone in response to
PTH
Calcitriol
Hyperphosphatemia
18
FGF23 has what effect on Pi
Increases Pi excretion
Slows down resorption
19
Potent regulator of Pi and Ca homeostasis synthesized and secreted from chief cells of what gland
Parathyroid hormone
Secreted from chief cells of parathyroid glands
20
PTH secretion is stimulated by what factors
Low plasma (ionized) [Ca2+]
21
How can the [Ca2+] in the plasma be sensed?
CaSR
Calcium sensing receptor
If a low [Ca] is senses, PTH secretion is induced by the receptor through Gq protein signaling
If high [Ca] os sensed, PTH secretion is inhibited by Gi protein
22
Vitamin D has what effect on the expression of PTH and CaSR
Vitamin D inhibits both these factors
23
Chronic hypercalcemia has what effect on synthesis/storage of PTH
Decreases synthesis/storage of PTH
Breaks down any stored PTH, releases inactive PTH fragments into circulation
24
Chronic hypocalcemia has what effect on synthesis/storage of PTH
Increases synthesis/storage
Results in hyperplasia of parathyroid glands
25
In severe hypomagnesia, what occurs to PTH
Inhibits PTH synthesis, storage, secretion
26
PTH receptor is what type of receptor, using what signaling cascade
GPCR
A cAMP cascade
An IP3/Ca2_ cascade
27
Low plasma [Ca] increases secretion of what hormone
PTH
28
Effects of PTH on bone, kidney, intestine
PTH increases bone resorption
Increases Ca and Pi in blood
Kidney - decreased Pi reabsorption, increased Ca reabsorption, increased urinary cAMP
Intestine - increased Ca absorption (PTH stimulated kidney cells to make and release calcitriol, which acts on intestine)
All increase plasma [Ca] to normal
29
Functions of vitamin D
Promotes mineralization of new bone by increasing Ca and PO plasma concentrations
Has opposing effects on Pi levels va action on kidney and intestine
Increases Ca and Po44 products to promote mineralization of new bone
30
Order of organs for vitD synthesis
Skin
Liver
Kidney
31
Liver enzyme of vitD synthesis
25-hydroxylase
32
Kidney enzyme of vitD sytnthesis
1alpha-hydroxylase
CYP1a
Forms active form of vitD
33
