Terms in this set (33)
What distinguishes bones from other CTs?
The feature that distinguishes bone from other connective
tissues is the mineralization of its matrix, which produces an
extremely hard tissue capable of providing support and protection.
The mineral is calcium phosphate in the form of
hydroxyapatite crystals [Ca10(PO4)6(OH)2].
Functions of the bone?
- Support and protection
- storage site for calcium and phosphate.
- homeostatic regulation of blood calcium levels
Which type of collagen in bone tissues?
The major structural component of bone matrix is type I
collagen and, to a lesser extent, type V collagen. Trace
amounts of other types such as type III, XI, and XIII collagens
have also been found in the matrix.
groups of noncollagenous
proteins (ground substance ) found in the bone matrix?
- Proteoglycan macromolecules
- Multiadhesive glycoproteins
- Bone-specific, vitamin K-dependent proteins
- Growth factors and cytokines
What is lacunae, canaliculi?
Within the bone matrix are spaces called lacunae (sing., lacuna) each of which contains a bone cell, or osteocyte. The osteocytes extend numerous processes into small tunnels called canaliculi
How can the osteocyte communicates?
Osteocyte processes communicate by gap junctions.
Cell types in bones?
- Osteoprogenitor cells
- Bone-lining cells
How are bone tissue classified?
Bone tissue is classified as either compact (dense) or spongy (cancellous)
How are bones classified?
Bones are classified according to shape; the location of spongy and compact bone varies with bone shape
How are bones classified on the basis of shape?
- Long bones
- Short bones
- Flat bones
- Irregular bones
What is the periosteum?
Bones are covered by periosteum, a sheath of dense fibrous connective tissue containing osteoprogenitor cells.
Describe the collagen fibers of the periosteum?
the collagen fibers of the periosteum are arranged
parallel to the surface of the bone in the form of a capsule.
The character of the periosteum is different where
ligaments and tendons attach to the bone. Collagen fibers
from these structures extend directly, but at an angle, into the
bone tissue, where they are continuous with the collagen
fibers of the extracellular matrix of the bone tissue. These
fibers are called Sharpey's fibers.
What is the endosteum?
The lining tissue of bothe the compact bone facing the marrow cavity and the trabeculae of spongy bone within the cavity is referred to as endosteum. The endosteum consists of osteoprogenitor cells that can differentiate into bone matrix-secreting cells, the osteoblasts, and bone-lining cells.
What is the bone marrow?
- Red bone marrow : consists of blood cells in different stages of development and a network of reticular cells and fibers.
- Yellow bone marrow : In later stages of growth and in adults, when the rate of blood cell formation has diminished, the tissue in the marrow cavity consists mostly of fat cells..
What is the Haversian systems?
Mature bone is largely composed of cylindrical units called osteons or Haversian systems. The osteons consist of concentric lamellae of bone matrix surrounding a central canal, the osteonal (haversian) canal, which contains the vascular and nerve supply of the osteon.
What are the interstitial lamellae?
the osteons are remnants of previous concentric lamellae called interstitial lamellae
What is the Circumferential lamellae?
A lamellar bone found at the entire inner and outer circumferences of the shaft of a long bone.
canals (Volkmann's canals)?
canals (Volkmann's canals) are channels in lamellar bone through which blood vessels and nerves travel from the periosteal
and endosteal surfaces to reach the osteonal canal;
they also connect osteonal canals to one another (Plate 11,
page 244). They usually run at approximately right angles to
the long axis of the osteons and of the bone (see Fig. 8.3).
Volkmann's canals are not surrounded by concentric lamellae,
What is the difference between mature spongy bone and mature compact bone?
Mature spongy bone is similar in structure to mature compact bone except that the tissue is arranged as trabeculae or spicules; numerous interconnecting marrow spaces of various sizes are present between the bone tissue.
What is nutrient foramina?
Nutrient foramina are openings in the bone through which
blood vessels pass to reach the marrow
What is the difference between mature bones and immature bones?
Immature bone does not display an organized lamellated
Immature bone contains relatively more cells per unit area
than does mature bone.
• The cells in immature bone tend to be randomly arranged,
whereas cells in mature bone are usually arranged with
their long axes in the same direction as the lamellae.
• The matrix of immature bone has more ground substance
than does the matrix of mature bone. The matrix in immature
bone stains more intensely with hematoxylin,
whereas the matrix of mature bone stains more intensely
The osteoprogenitor cell is derived from?
The osteoprogenitor cell is derived from mesenchymal
What triggers the osteoprogenitor's differentiation?
Transcription factor called core binding factor alpha-1 (CBFA1_
Where are the osteoprogenitor cells?
Osteoprogenitor cells are found on the external and internal surfaces of bones and may also reside in the microvasculature supplying bone.
Osteoprogenitor cells components?
Osteoprogenitor cells comprise the periosteal cells that form the innermost layer of the periosteum and the endosteal cells that line the marrow cavities, the osteonal (haversian) canals, and the perforating (volkmann's) canals.
What is osteocytes?
The mature osteoblast which is completely surrounded by osteoid or bone matrix
Functions of osteocytes?
- Maintaining the bone matrix
- Mechanotransduction, the process by which the osteocyte responds to mechanical forces applied to the bone
- Maintain calcium homeostasis
Functional states of the osteocyte?
- Quiescent osteocytes
- Formative osteocytes
- Resorptive osteocytes
What are bone-lining cells?
Bone-lining cells are derived from osteoblasts and cover bone that is not remodeling
What is periosteal cells, endosteal cells
Bone-lining cells on external bone surfaces are called periosteal cells, and those lining internal bone surfaces are often called endosteal cells.
What are osteoclasts?
Osteoclasts are large, multinucleated cells found at sites where bone is being removed.
What is the resorption bay (howship's lacuna)?
A shallow bay which is a result of osteoclast activity
How can the develoopment of a bone classified?
The development of a bone is traditionally classified as endochondral or intramembranous.