Chp 6: Bone Tissue B
Terms in this set (22)
Structure of a Flat Bone
The parietal bone of the skull
Resembles a sandwich of spongy bone
Between two layers of compact bone
Within the cranium, the layer of spongy bone between the compact bone is called the diploë
Bone (Osseous) Tissue
Dense, supportive connective tissue
Contains specialized cells
Produces solid matrix of calcium salt deposits
Around collagen fibers
Characteristics of Bone Tissue
Dense matrix, containing:
Deposits of calcium salts
Osteocytes (bone cells) within lacunae organized around blood vessels
Form pathways for blood vessels
Exchange nutrients and wastes
Mature bone by weight consists of 35% organic and 65% inorganic material.
Two thirds of bone matrix is calcium phosphate, Ca3(PO4)2
Reacts with calcium hydroxide, Ca(OH)2
To form crystals of hydroxyapatite, Ca10(PO4)6(OH)2
Which incorporates other calcium salts and ions
One third of bone matrix is protein fibers (collagen)
Consists of Collagen and Proteoglycans
Consists of a Calcium Phosphate crystal called Hydroxyapatite.
Covers outer surfaces of bones
Consists of outer fibrous and inner cellular layers
on the outside
Covers all bones except parts enclosed in joint capsules
Made up of an outer, fibrous layer and an inner, cellular layer
Perforating fibers: collagen fibers of the periosteum
Connect with collagen fibers in bone
And with fibers of joint capsules; attach tendons, and ligaments
Functions of Periosteum
1. Isolates bone from surrounding tissues
2. Provides a route for circulatory and nervous supply
3. Participates in bone growth and repair
Make up only 2% of bone mass
Bone contains four types of cells
Are associated with bone formation.
Have extensive endoplasmic reticulum and numerous ribosomes.
Ossification or Osteogenesis - Is the formation of bone by osteoblast
Immature bone cells that secrete matrix compounds (osteogenesis)
Osteoid — matrix produced by osteoblasts, but not yet calcified to form bone
Osteoblasts surrounded by bone become osteocytes
Secrete acids and protein-digesting enzymes
Giant, multinucleate cells
Contain numerous lysosomes
Dissolve bone matrix and release stored minerals (osteolysis)
Derived from stem cells that produce macrophages
Develop from circulating monocytes (one type of white blood cells).
Are found around the surfaces of bone;
Function in bone resorption (degradation)
Important in the development, growth, maintenance, and repair of bone.
Are mature bone cells.
Are the principal cells of bone tissue.
Lacunea - Are spaces occupied by the osteocyte cell bodies.
Canaliculi (little canals) - Are spaces occupied by the osteocyte cell processes.
Mature bone cells that maintain the bone matrix
Live in lacunae
Are between layers (lamellae) of matrix
Connect by cytoplasmic extensions through canaliculi in lamellae
Do not divide
Two major functions of osteocytes
To maintain protein and mineral content of matrix
To help repair damaged bone
Mesenchymal stem cells that divide to produce osteoblasts
Located in endosteum, the inner cellular layer of periosteum
Assist in fracture repair
Are stem cells that have the ability to become osteoblasts and chondrioblasts.
Note: Osteoblasts are derived from osteochondral progenitor cells, and osteocytes are derived from osteblasts.
Origin of Bone Cells
Connective tissue develops embroyologically from mesenchymal cells.
Have the ability to replicate and give rise to more specialized cell types.
Bone building (by osteoblasts) and bone recycling (by osteoclasts) must balance
More breakdown than building, bones become weak
Exercise, particularly weight-bearing exercise, causes osteoblasts to build bone
Woven and Lamellar Bone
According to the organization of collagen fibers within the bone matrix, bone tissue is classified as (a) Woven bone or (b) Lamellar bone.
Collagen fibers are randomly oriented in many direction.
Is mature bone that is organized into thin sheets or layers called lamellae.
Cancellous and Compact Bone
Bone woven or lamellar are classified according to the amount of bone matrix relative to the amount of space present within the bone.
Cancellous bone has less matrix and more space while Compact bone has more matrix and less space.
Consists of interconnecting rods or plates of bones called trabeculae.
Between the trabeculae are spaces that in life are filled with bone marrow and blood vessels.
Note: Cancellous bone is sometimes called Spongy Bones because of its porous appearance.
Endosteum on the inside
An incomplete cellular layer:
Lines the medullary (marrow) cavity
Covers trabeculae of spongy bone
Lines central canals
Contains osteoblasts, osteoprogenitor cells, and osteoclasts
Active in bone growth and repair