Select ALL That Apply

.Osteoclasts:

A.are derived from osteoblast, the osteogeniccells of developing bone.

B.are giant, multinucleated cells with severalnuclei and produce a secretion rich in acid phosphatase.

C.are essential for stabilizing the bloodcalcium level during chronic blood hypocalcemia.

D.are derived from osteogenic cells

E.only occur in regions of developing bone.

****

Control of calcium metabolism is accomplished by theeffect of several hormone on several different organs. Which of thefollowing is true concerning the control of calciummetabolism?

A.PTH (parathyroid hormone) causes an increasein plasma calcium by its actions on bone and the kidney.

B.Calcitriolcauses an increase in absorption ofcalcium from the lumen of the digestive tract.

C.Calcitonin causes a decrease in plasmacalcium by suppression bone resorption.

D.When plasma calcium increases, PTH decreasesand calcitonin increases.

E.PTH can rapidly increase plasma calcium levelby its action on the osteocytic membrane system.

***

.Which of the following statements would be trueconcerningcompounds involved in calcium metabolism?

A.The most life-threating consequence ofhypocalcemia is reduced blood clotting.

B.Vitamin D can be synthesized from acholesterol derivative in the skin when exposed to sunlight.

C.PTH facilitates the activation of vitamin Dwhich is necessary for the absorption of calcium and phosphate inthe gut.

D.1,25 dihydroxycholecalciferol is the carrierprotein for calcium in the blood.

E.The most rapid response to hypocalcemia isthe activation of the osteocytic membrane system byPTH.  

****

.Endochondral bone:

A.development proceeds from masses of hyalinecartilage with shapes similar to future bony structures.

B.growth proceeds from a specialized region atthe ends of the diaphys is called the epiphyseal plate.

C.is first laid down as a membrane like layerof primitive connective tissue that remains soft and membrane likethroughout life.

D.is derived from the articular cartilage ofthe epiphysis.

E.is composed of only compact bone and cannotform the cancellous (spongy) bone found the epiphysis of longbone.