Bone II - Osteoclast Activity and Regulation

parathyroid hormone, calcitonin

What 2 hormones control osteoclast activity?

RANK, RANK-L, OPG

What 3 molecules control osteoclast activity at the cellular level?

corticosteroids, glucocorticoids, IL-1

What are some examples of cytokines influencing RANK, RANK-L and OPG levels?

carbonic, citric, lactic

What are some organic acids involved in focal decalcification?

Howship's lacunae

What are the depression left in eroded bone by osteoclasts?

cathespins

What can inhibitors attack to regulate osteoclast activity?

levels of various cytokines

What determines the levels of RANK, RANK-L and OPG?

osteoprotegerin

What does OPG stand for?

binds to RANK to stimulate primitive osteoclast development into mature osteoclasts

What does RANK-L do?

denosumab, antibody which binds to RANK-L

What drug inhibits RANK-L and how?

calcium supplements, vitamin D, increase calcium levels

What drugs inhibit PTH and how?

hormonal replacement therapy, biphosphonates

What drugs/treatments reduce osteoclast activity?

cathespins

What enzymes digest collagen?

PTH, exercise, anti-sclerostin antibodies

What inhibits sclerostin?

acid hydrolases digest extracellular material

What is involved in the second step of bone resorption?

molecule involved in osteoclast/osteoblast interaction

What is sclerostin?

focal decalcification by organic acids

What is the first step of bone resorption by osteoclasts?

decoy molecule that blocks RANK-L preventing binding to primitive osteoclasts

What is the function of OPG?

forms seal so secretions don't leak to other areas of bone

What is the importance of the collar on osteoclasts?

increase surface area for secretion and resorption

What is the importance of the ruffled border of osteoclasts?

primitive osteoclasts

Where is RANK found?

osteoblasts

Where is RANK-L found?

thyroid gland

Where is calcitonin produced?

digesting osteoid

How can osteoblasts prepare a surface for osteoclast activity?

increases osteoblast and osteoclast activity, bone mass decreased

How does PTH affect bone resorption?

reduces osteoclast activity by reducing no. of folds, no. of osteoclasts and osteoclast movement

How does calcitonin affect bone resorption?