What is the total serum calcium?
2.1-2.6 mM
total ionized calcium?
REMEMBER 40-10-50
40% : calcium is combined with plasma proteins; not diffusible
10%: calcium is combined with substances as anions, is diffusible but not ionized
50%: is diffusible & ionized. It is important for the functions of the heart, nervous system
List 2 functions of calcium in the body?
1. it enters in the structure of bones, teeth, connective tissue elements and cellular cement substances
2.ionized calcium is necessary for blood coagulation, muscle contraction & nerve function
List 2 functions of calcium in the body?
1. it enters in the structure of bones, teeth, connective tissue elements and cellular cement substances
2.ionized calcium is necessary for blood coagulation, muscle contraction & nerve function
what is the solid form of calcium in the body called?
hydroxylapatite (HA)
function of phoshate acts on what 3 things?
1. skeleton
2. metabolism
3. signaling
function of phosphate on skeleton?
mechanical strength; structural component of bone and teeth
function of phosphate on metabolism?
ATP, phosphocreatn, glucose 6 phosphate
function of phosphate on signaling?
cAMP, IP3 phosphorylation/dephosphorylation of enzymes
osteoblasts hormone
parathyroid
osteoblasts mediator
RANK (activator of NFkB)
osteoclasts hormone
vitamin D
osteoclasts mediator
RANKL
bone hormone and mediator
hormone: calcitonin
mediator: NFkB
kidney: hormone and mediator:
hormone: estrogen
mediator: osteoprotegerin
GI tract hormone and mediator
hormone: glucocorticoids
mediator: osteoclacin and calbindin
clasts
breakdown
blasts
build up
3 hormones concerned with regulation of calcium metabolism?
1,25 vitamin D3
parathyroid hormone
calcitonin
calcitonin is secreted from...
perifollicular cells of thyroid gland
calcitonin reduces...
blood calcium ion concentration
parathyroid hormone is secreted from
parathyroid gland
parathyroid hormone is a calcium ___ hormone
elevating
parathyroid hormone effect on bone:
1. rapid phase: it activates osteoclasts to promote calcium and phosphate absorption (min)
2. slower phase: proliferation of osteoclasts with increased osteoclastic resorption of bone (days/weeks)
parthyroid hormone action on kidney
absorption with LOSS OF PHOSPHATE in urine, while increasing Ca absorption
parathyroid hormone on intestine
it increases absorption of Ca & phosphate
calcitonin is a calcium ____ hormone
lowering
function of Calcitonin
INCREASES INHIBITS DECREASES!
INCREASES: calcium excretion in urine & decreases & decreases blood calcium ion concentration
INHIBITS osteoclsts function--> reducing bone resorption, thus decreasing serum Ca & phosphate
DECREASES formation of new osteoclas
absorption of calicum is ___ in cases of calcium deficiency & ____ in presence of calcium excess
increased; decreased
absorption of calcium is facilitated by..
1,25 dihydroxyvitamin D3, lactose, and proteins
calcium absorption is inhibited by...
phosphate and oxalate because these form insoluble salts with calcium in the intestine
phosphate is absorbed from the ___, when excess calcium is in the diet
intestine
oxalate in combination with calcium...
creates an insoluble salt!
what is the rate limiting factor in active calcium transport?
CaBP
What is the most important effect of calcitriol?
Control of the expression of gene coding for the synthesis of the protein CaBP which regulates the migration of calcium across intestinal cells
The PTH-calcitriol system is involved in bone ___ and increases the ____ of ____ by the _____
Bone resorption; increases the reabsorption of calcium by the renal tube
How does 1,25 vitamin D3 increase absorption from the intestine?
Causes the calcium binding proteins to form in the intestinal epithelial cells.
what is vitronexin?
glycoprotein in serurm that promotes cell adhesion and spreading ; rumored to be involved in TUMORE MALIGNANCY
3 components of cross talk between osteoblasts and osteoclasts
RANK
RANKL
OPG
Rank is a...
transmembrane receptor protein expressed on pre-osteoclasts
what happends when RANK interacts with RANKL?
osteoclastogenesis occurs
PTH ___ expression of RANKL and ___ production of OPG which then does what?
induces RANKL
INHIBITS OPG
which is -->cranking up the generation of osteoclasts
RANKL is an essential ___ for osteoclastogenesis
CYTOKINE
RANKL is made in
OSTEOBLASTS
___ increases the amount of OPG
estradiol
withdrawal of estrogens leads to -__ of both osteocytes and oseoblasts
apoptosis
___ induces the anti-apoptotic protein Bcl-2 in osteoblasts
E2
PTH: when Ca2+ falls
cAMP rises and PTH is secreted
what inhibits PTH gene expression, providing another level of feedback control of PTH
1,25 (OH)2 D
Osteoporosis
Reduced bone density and mass
Osteoclasts are involved in Bone ___
Breakdown
Osteoblasts are involved in Bone ___
Formation
What is SERM
Selective
Estrogen
Receptor
Modulator