Flashcards in Patho: Exam 2: Bone Deck (59)
Describe the Cortical bone?
hard outer layer- compact bone tissue- forms a cortx ( outside) of most bones
how poris is Cortical bone?
What percent of the total bone mass is made up by cortical bone?
80% of the total bone mass
Cortical bone also contains what type of canals?
Contains Haversian and osteons
Trabecular bone (cancellous or spongy bone)
Trabecular bone (cancellous or spongy bone)
What is the function of Trabecular bone ?
Allows room for blood vessels and marrow
What percent of bone mass does Trabecular bone account for?
20% of bone mass(10x surface area of compact bone)
how poris is Trabecular bone ?
Porosity 0f 30-90%
Changes in the rate of bone turnover are manifested principally in what bone?
The Trabecular bone or cancellous bone
All bones contain what type of bone?
cancellous & cortical elements but the proportions differ
Femur: the shaft is cortical bone and morrow is fat, the ends are thing cortx with course cancellous (Treabecular) benign prominent. Therefore you have bone turn over in the ends.
The skeletal system is vital during life, it has an essential role in what? (1-5)
1: Mineral homeostasis: this is where we can store and retain minerals such as Ca+.
2: Houses hematopoietic elements: this changes with age
3: Mechanical support for movement
4: Protects Viscera: Internal organs
5: Determines body size and shape
Extends from subarticular bone plate to the base of the growth plate
coarse cancellous bone: Important in hematogenous infections tumors and skeletal malfomations.
Body or shaft of the bone ( zone between 2 metaphysis)
Despite its stony hard structure, the bone is a dynamic tissue that is continuosly what?
Resorption, what does this mean in regards to drug therapy, if a drug increases resorption?
Drugs that are antiresorptive?
Increase the osteoclast activity so you are breaking down bone
Block the break down of bone, stop osteoclast from breaking down bone.
The process of reprobation, renewal, and remolding is carried out by several different types of one cells that are regulated by what?
There are Four types of cells:
Components of bone
2.Mineralized phase: a lot of calcium, phosphate ect.
3.Organic matter- Hydroxyapatite, Other proteins, Osteocalcin, Osteopontin.
How are Osteoblast stimulated?
o With the stimulation of RunX2 and CBFA1 transcription factors Osteopogentor cells undergo final differentiation and become osteoblast
o WNT ( from the Osteoprogentor cells) binds to the LRP 5/6 LDL receptor related portien 6 and 5receptors and allows for Beta Catenin to be the anchor into the laminar bone area and and prdoduce hydroxiappitiate to make matrix
• With out WNT, beta catenin will become proliferated and destroyed.
o BMP- Bone Morphogenic protein- stimulates the osteoblast even more, proliferates like crazy.
• In 2002 the used BMP was approved for use in spinal fusions, they would use a collagen sponge (called Infuze) and infuse it with BMP, and when it gets inserted it stimulates bone growth.
• Now in 2012 they found that BMP actually can lead to cord stenosis and cancer.
The Osteopogentor cells can also produce surface osteoblast that can get triggered to produce cytokines or become to become activated. The cytokines that are produced actually activate osteoclast. This allows for continuous building and breaking.
what is the function of osteoblast?
Osteoblast are located on the surface of the bones. These cells synthesize, transport and arrange the many proteins of the matrix and initiate the process of mineralization.
Osteoblast have receptors that bind regulatory hormones such as:
regulatory hormones ( parathyroid hormone, Vit D, Leptin and estrogen)
What do Cytoblast produce to make the matrix
Osteoblast produce Hydroxyapatite, what is it?
A combination of calcium, phosphate and hydroxide ( OH-)
Osteoblast also produce Type I collagen what is that?
Can determine the strength of the bone, it will be wolven fist and then it will turn into lamellar bone
Osteoblast also produce Osteocalcin, what is that?
maker for osteoblast activity, used clinically in patients who have osteoperosis, if you give them a medication that is suppose to increase osteoblast activity. It will take 2 years to see a change on a bone density scan, so you can order an osteoalcin lab to see if the medication is working.
PTH dematerializes things, why is the receptor on the osteoblast
to produce the cytokines to stimulated osetoclast to break down bone
What is the effect of Leptin receptors on the osteoclast?
there is increased lepin causes increased stimulation of osteopbalst