Test 2 Flashcards
Function of Bone
- Protection of vital organs
- Support for the body
- The mechanical basis for movement
- Storage of salts (calcium)
- Continuous supply supply of new blood cells
- Produce Growth factor storage such as Bone morphogenetic Protein (BMP)
what is BMP
BMP are a growth factors that induce bone and cartilage formation utilized utilized in long bone fractures and spinal fusion.
what is FBG
Produce fibroblasts Growth Factors
involoved in angiogenesis (angio-G-vessel) wound healing, embryonic development (neural, limb development)
What are the two types of bones
- Compact
2. Spongy or Cancellous
Long Bones
they have a superficial thin layer of compact bone around a central medullary (marrow cavity). Within this cavity that contains marrow of adult bones, that produce all types of blood cells
Osteoblast
produce cell
Compact Bone provides:
strength for weight bearing
Long Bones are designed for:
rigidity and attachment of muscles, ligaments.
Cancellous bone is located:
near the ends of the bones in order to adapt to different angles of stress placed on the bone
feel of the cancellous bone
it is spongy and lattice like with porosity greater than 70%
Structure of the cancellous (spongy) bone
although quit rigid, it is weaker and less stiff than compact bone
Trabeculae
fine bone spicules located in cancellous bone
- the trabecular adapt to the direction of the imposed stress on the bone, providing strength while maintaining low weight in the structure
- the high porosity gives spongy bone high energy storage capacity so that it becomes a crucial element in the energy absorption and stress distribution when loads are applied to the skeletal structure
Between the Trabeculae is
marrow that produce most of the blood cells (erthryocytes)
the matrix is also laminar formation, like compact bone, however, the concentric rings are irregular and osteoblasts are more spread out, thus the lattice appearance
Bone mass of Compact Bone
80% of the bone mass is dense and offers strength and stiffness to the skeleton
Periosteum
- a thin white membrane that covers the outside of the bone
- specialized connective tissue that covers all of the bones
external layer of the compact bone
contains numerous blood vessels to perfuse the bone
internal layer of the compact bone
contains many osteoblasts that form new bone referred to as being osteogenic and are responsible for increasing the width of the bone.
Sharpley’s Fibers
- located inside the compact bone
- secures the periosteum to the bone
- tendons merge with periosteum to transfer the force generated by the muscle to the bone moment
- the way that tendons and ligaments attach to the outer layer of there periosteum and transfer forces into the bone
Endosteum
a membrane that lines the medullary canal and the walls of the spaces in the cancellous bone. It is thinner and less well defined than the periosteum but does not have hematopoietic and osteogenic potencies
Osteon
- the basic structure of the compact bone
- lacuna located here
- Haversian Canal located here
lacuna
small spaces within lamella
Haversian Canal
central canal of the osteon
- Each Haversian Canal contains an arteriole, venue and nerve. Which allows blood and nerves to perfuse the bone
- Each Haversian Canal is connected by Volkmar’s Canal
- –Volkman’s Canals are connected to periosteal arteries
Osteoblasts
- bone cells
- Osteoblasts of the Lacunae, Periosteum, and Endosteum deposit osteoid tissue in a concentric ring
- the bone deposition ceases when osteoid tissue begins to encroach on the blood vessels and nerves in Haversian’s canal supplying the area
- the new lamella laid in concentric rings impression the osteoblasts, which now transition into mature bone cells, are connected by small canals called CANALICULI which allows blood to flow with nutrients to each lacunae
- therefore, the bone has an elaborate canal system in order for blood to flow thou the bone
- within a few days, after the osteoid tissue is formed as concentric rings, calcimined phosphorus begin to precipitate on the osteoid tissue. The osteoid tissue covert the calcium and phosphorus to hydroxyapatite crystals, which is the material that gives bone its rigidity
Osteocytes
- Mechanosensory cells of bone, involved in the transaction of mechanical loads into electrical impulses, which allows bone to grow and adapt to the body’s mechanical needs for strength
- Also appear to use some molecular signaling pathways that are familiar from other tissues, such as a generation of nitric oxide
- secrete osteopontin
nitric oxide
a powerful vasodilator, which would be important when additional calcium and phosphorus is needed for increased bone production
protoglandins
influence the uptake of calcium
osteopontin
initiates the process by which osteoclasts develop ruffled borders, which penetrate bone then secrete enzymes that dissolve bone
Osteoporosis
loss of bone mass leading to fractures
- sites most affected are weight bearing structure such as vertebrae, hip and femoral neck
- cancellous bone is affected due to the fact that it has a higher turnover rate
- both men and women experience bone loss due to age
