releasing the Ca2+ stored in the bones when circulating Ca2+ falls
What is hydroxyapatite?
Calcium and phosphate
Hydroxyapatite forms mineralized collagen
If 1000 mg of calcium comes in through diet, _____ gets excreted out through poop, _____ gets in the extracellular fluid, and exchanges Ca2+ with _____ and ______, resulting in net excretion of ____ out the kidneys
800
200
Bones and kidneys
200
If 20 mg of dietary phosphorus intake, _____ gets absorbed into ECF from the intestines, and ____ are secreted back into the intestines, netting total of ___ out through poop
16
3
7
The extracellular fluid exchanges phosphorus with the ____ and ___, much like calcium exchange.
Bone and kidneys
Resulting in the excretion of phosphorus out the kidney
Plasma concentration of Ca2+ is ranges _______, and phosphorus is ranges ______
9-11 mg/dL
2.5-4.5 mg/dL
What type of calcium is physiologically active?
free, ionized Ca2+
Complexed to anions are not physiologically active
Parathyroid gland senses ______ calcium in the blood in order to regulate
Free ionized Ca2+
Acidemia means that there is ______ [H+], so ______ amount of H+ is bound to albumin, making _____ of Ca2+ on albumin, therefore ______ of [Ca2+] circulating in plasma
Increased
Increased
less
Increased
Alkalemia means there is ______ [H+], so ______ amount of H+ is bound to albumin, making _____ of Ca2+ on albumin, therefore ______ of [Ca2+] circulating in plasma
Decreased
Decreased
More
Decreased
Parathyroid hormone is synthesized and secreted by which cell?
Chief cells
1,25-dihydroxyvitamin D is the ______ form of vitamin D. It ____ Ca2+ absorption from the intestines
Active
Stimulates
What stimulates bone resorption, what reduces it?
PTH and active Vitamin D (1,25-dihydroxyvtiamin D) stimulate
Calcitonin reduces it
What effect does PTH have on renal Ca2+ reabsorption?
Increases calcium renal reabsorption
What is needed in order to absorb Ca2+ from diet?
1,25-dihydroxyvitamin D (active vitamin D)
What is needed to reabsorb Ca2+ from kidneys?
PTH
T/F: [Ca2+] and [PO4-] levels are directly proportional in plasma, one goes up, the other goes up
False; when Calcium concentration increases with parathyroid hormone stimulation, concentration of phosphate goes down. This is because PTH increases reabsorption of Ca2+ and decreases phosphate reabsorption
Extracellular calcium binds _______ receptor that is coupled to a _______ protein, which would activate ______, which is an enzyme that converts ______ to _____ and ____
Calcium sensing
Heterotrimeric G protein
Phospholipase C (PLC), converts PIP2 to IP3 and DAG
IP3 within the parathyroid chief cell causes ______of Ca2+ from internal stores, and DAG stimulates _______. And combination of these elevates intracellular ______ and this actually _____ release of ____ granules
Release
PKC
Intracellular [Ca2+] goes up, and PKC inhibits release of PTH granules
Increased in _____ in the urine could indicate hyperparathyroidism
cAMP (also increased in urine phosphate and calcium)
where does conversion of 25-OH-cholecalciferol to the active form of vitamin D takes place?
In the kidney, PTH is necessary for this conversion
Primary hyperparathyroidism would have ____ PTH, ______ [Ca2+], _______ [phosphate]
Secondary hyperparathyroidism would have ____ PTH, ______ [Ca2+], _______ [phosphate]
Increase
Decrease
INCREASE
Etiology of secondary hyperparathyroidism?
Renal disease, vitamin D or calcium deficiency, poor fat absorption, cortisol, intestinal malabsorption of vitamin D
Primary hypoparathyroidism would have ____ PTH, ______ [Ca2+], _______ [phosphate]
Decrease
Decrease
Increase
Etiology of primary hypoparathyroidism?
Thyroid surgery, congenital agenesis or hypoplasia of the parathyroid glands
Secondary hypoparathyroidism would have ____ PTH, ______ [Ca2+], _______ [phosphate]
Decrease
Increase
increase
Etiology of secondary hypoparathyroidism?
Vitamin D toxicity
Pseudohypoparathyroidism is _______
Resistance to PTH
Resulting in increased PTH but decrease in [Ca2+] and increased [phosphate]
Both post-menopausal osteoporosis and immobilization osteoporosis have these effects on ____ PTH, _____ [Ca2+] and ______ [phosphate]
Decrease
Increase
Increase
Dietary vitamin D is _____, and in the liver it is altered into ______, which is an ______ form. In the kidney, it becomes _______ which is _____ form
Cholecalciferol
25-OH-cholecalciferol
Inactive
1,25-dihydroxyvitamin D
Active
T/F: PTH activates osteoblast first, then it will send cytokines which the activate mature osteoclasts to stimulate bone calcium resorption
True; some bone would release alkaline phosphatase to rescue the bone that is getting weakened by bone resorption
PTH on kidney: would _____ phosphate reabsorption , and ____ urine cAMP.
Decrease; due to inhibition of Na+/Phosphate cotransport
Increase
With renal destruction, how does it alter serum phosphate concentration vs calcium?
Phosphate would go up and calcium goes down
Therefore PTH would be up, and more bone resorption
What is familial hypocalciuric hypercalcemia?
Loss of function of the calcium sensing receptor
Ca increased and normal PTH
Requiring higher Ca concentration to turn off PTH
Active vitamin D stimulates the expression of ______ ligand that is made by osteoblast, which is an important regulator of _____
RANKL
Regulate osteoclast maturation and function
T/F: vitamin D deficiency would lead to lowered levels of calcium and phosphate in the blood, thereby activating PTH causing mobilization of calcium and phosphorus from bone and as a result, calcium level goes back to normal but phosphate remains low= poor bone mineralization
True
Rickets is vitamin D deficiency seen in ______, and osteomalacia is vitamin D deficiency in ______
Children
Adult
T/F: calcitonin is produced by the Parafollicular cell (C cell) of the parathyroid
False; it is produced by the C cells in the thyroid