What is the function of the osteoclasts?
Osteoclasts are the cells that degrade bone to initiate normal bone remodeling and mediate bone loss in pathologic conditions by increasing their resorptive activity. They are derived from precursors in the myeloid/monocyte lineage that circulate in the blood after their formation in the bone marrow.
What enzyme is produced by resorptive cells?
Cathepsin K is a collagenolytic papain-like cysteine protease that is mainly expressed in osteoclasts, and is secreted into the resorptive pit.
What does resorptive mean?
Resorption is the breakdown and assimilation of old bone in the cycle of bone growth. The process of resorption (remodeling) involves the removal of hard bone tissue by osteoclasts followed by the laying down of new bone cells by osteoblasts.
What hormone inhibits osteoclast activity?
Calcitonin
Calcitonin reduces calcium levels in the blood by two main mechanisms: It inhibits the activity of osteoclasts, which are the cells responsible for breaking down bone.
How do you reduce osteoclasts?
The two families of presently available anti-resorptive drugs, namely bisphosphonates and denosumab, dampen activity of osteoclasts by reducing their number. In consequence, these agents also arrest bone remodelling eventuating suppressed formation as well as resorption.
What are 2 types of bone tissue?
Bone is made up of compact tissue (the hard, outer layer) and cancellous tissue (the spongy, inner layer that contains red marrow).
Which vitamin D is best for osteoporosis?
The National Osteoporosis Foundation (NOF) recommends an intake of 800 to 1000 international units (IU) of vitamin D3 per day for adults over age 50 (NOF 2008).
What does resorption mean in kidney?
Substances that enter the nephron are not all excreted but may exit the tubule and flow back into the blood. This is called resorption (reabsorption).
Which hormone is responsible for bone growth?
Testosterone is important for skeletal growth both because of its direct effects on bone and its ability to stimulate muscle growth, which puts greater stress on the bone and thus increases bone formation. Testosterone is also a source of estrogen in the body; it is converted into estrogen in fat cells.
Was sind die Vorteile von Osteoklasten?
Ihre Arbeit umgreift zwei verschiedene Mechanismen: die Demineralisierung der Knochensubstanz und den tatsächlichen Abbau des Knochens. Osteoklasten bremsen durch ihre Arbeit das Knochenwachstum und verhindern maßlose Wachstumsprozesse und Wucherungen.
Was sind Osteozyten und Wie funktionieren sie?
Osteozyten sind eingeschlossene Osteoblasten, die zur Reife gelangt sind. Wenn ein Knochen von einer Fraktur oder Mikrofraktur betroffen ist, sterben die Osteozyten wegen mangelnder Nährstoffzufuhr ab und rufen durch die freigesetzten Substanzen die Osteoklasten auf den Plan. Die Arbeit der Osteoklasten setzt sich aus zwei Mechanismen zusammen.
Was ist der Unterschied zwischen einer verminderten und einer gesteigerten Osteopetrose?
Eine verminderte Aktivität der Osteoklasten kann daher ebenso viel Schaden anrichten wie eine gesteigerte. Bei der genetisch bedingten Osteopetrose liegt zum Beispiel eine stark verminderte Osteoklastentätigkeit vor.