McCumbee- Calcium Homeostasis Flashcards
(79 cards)
Normal plasma concentration of calcium?
Between 8.5 and 10.5 mg/dl
___% of calcium is free ionized calcium, the biologically active form
50
What are the 3 principle organs involved in Ca and Phosphate homeostasis?
Small intestine
Skeleton
Kidneys
The principle regulators of calcium and phosphate homeostasis are _____ and _____
PTH
Vitamin D
What four things are associated with negative calcium balance (net calcium loss)?
Immobilization of a limb
Weightlessness in space
Prolonged bed rest
Certain forms of cancer
Positive calcium balance (net calcium gain) is associated with?
Skeletal growth
Type of bone
Makes up 80% total bone mass
Particularly strong because of a densely packed matrix
Shafts and ends of long bones
Surface of other bones
Cortical bones
Where is cortical bone found?
Shafts and ends of long bones
Surface of other bones
Made of interconnecting bone spicules
Contains 80% of bone surface, but 20% of bone mass
Insides of flat bones
Vertebral bodies
Epiphyses and interior of the diaphysis of long bones
Trabecular bones
Where are trabecular bone found (interconnecting bony spicules)
Inner portion of flat bones
Vertebral bodies
Epiphyses and interior of the diaphysis of long bones
Remodeling of bones is essential for?
Maintaining structural integrity of skeleton
Supporting mineral homeostasis
Which type of bone has the highest yearly remodeling rate?
Trabecular bone (20% per year)
[cortical bone remodels at a rate of 4% per year]
This system is the primary mechanism thru which osteoblasts and osteoblast lineage cells regulate osteoclastogenesis and bone remodeling
OPG/RANK-L/RANK system
RANK-L expression is ______ by PTH and Vitamin D
Stimulated
(RANK-L is the surface ligand on osteoblast lineage cells that tell the osteoclast precursors, which have RANK receptors, where to bind)
RANK-L expression is stimulated by _____ and ______
PTH
Vitamin D
(RANK-L is the surface ligand on osteoblast lineage cells that is where the osteoclast precursor cells are able to bind with their RANK receptors)
RANK-L expression is _______ by estradiol.
Inhibited
(RANK-L is the surface ligand on osteoblast lineage cells that tell the osteoclast precursors, which have RANK receptors, where to bind)
RANK-L expression is inhibited by ______ .
Estradiol
(RANK-L is the surface ligand on osteoblast lineage cells that tell the osteoclast precursors, which have RANK receptors, where to bind)
_________ are able to release OPG (osteoprotegerin), which is a soluble protein that binds RANK-L and prevents it from activating RANK
Osteoblasts and osteoblast lineage cells
________ inhibits RANK-L induced differentiation of proteoclasts when necessary by preventing it to activate RANK in osteoclasts and preosteoclasts.
OPG
OPG production is stimulated by ________
Estradiol
It is inhibited by PTH
OPG production is inhibited by ________
PTH
It is stimulated by estradiol
What does M-CSF do?
Macrophage colony stimulating factor
Promotes the early differentiation of monocyte/macrophage lineage cells and works with RANK-L to PROMOTE osteoclastogenesis
M-CSF also bind receptors in osteoclast precursors causing them to proliferate and enhancing their survival
(Resorption)
Where is M-CSF secreted from?
Osteoblast lineage cells
Osteoprotegin ________ the activity of the RANK-Ligand system
Antagonizes
