What is bone?
A hard tissue consisting of cells in a matrix of ground substance and collagen fibers.
Long bones consist of a shaft and two ends. What are the ends called?
Long bones consist of a shaft and two ends. What is the shaft called?
Long bones consist of a diaphysis with two epiphyses. What separates them?
epiphysial line (or plate)
The epiphysial plate separates the diaphysis from the epiphysis in children. What is the area of transition between the epiphyseal plate and the diaphysis called?
Long bones consist of a diaphysis with two epiphyses. What type of bone marrow is found within the cavity of the diaphysis?
Long bones consist of a diaphysis with two epiphyses. What type of bone marrow is found within the spongy bone of the epiphyses?
Flat bones consist of an area spongy bone between two layers of compact bone. What is this middle layer called?
What is the periosteum?
A dense, double-layered connective tissue covering that surrounds the outer surface of bone.
What is endosteum?
A thin vascular membrane of connective tissue that lines the inner surface of the medullary cavity and central canals of long bones.
What are Sharpey's (perforating) fibers?
Bundles of strong predominantly type I collagen fibers connecting periosteum to bone.
Compact bone, also called cortical bone, forms the outer layer of many bones. What are the basic units of compact bone?
osteons (Haversian systems)
Osteons are the basic units of compact bone. What is the central canal?
A large canal in the center of each osteon that contains nerves and blood vessels.
Haversian canals (central canals) in the center of each osteon contain nerves and blood vessels. What are Volkmann's canals?
Smaller accessory canals that connect adjacent Haversian canals.
The central canal is a large canal in the center of each osteon that contains nerves and blood vessels. What are lamellae?
Concentric layers of bone tissue surrounding the central canal of each osteon.
Lamellae are concentric layers of bone tissue surrounding the central canal of each osteon. What are lacunae?
Small cavities situated between the lamellae of compact bone which house osteocytes.
Lacunae are small cavities situated between the lamellae of compact bone which house osteocytes. What are caniliculi?
Microscopic canals between the lacunae of compact bone through which processes of the osteocytes project.
Spongy bone, also called cancellous bone, is found with the medullary cavity and ephiphyses. What does spongy bone consist of?
It consists of numerous bony bridges called trabeculae.
Bone is a matrix consisting of an organic component and inorganic component. What comprises the inorganic component?
Mainly calcium and phosphorus, in the form of calcium hydroxyapatite [Ca10(PO4)6(OH)2] crystals (about 65% of dry weight of bone).
Bone is a matrix consisting of an organic component and inorganic component. What comprises the organic component?
Mainly type I collagen (90%), along with a ground substance (10%) consisting of hyaluronic acid, water, and proteins (about 35% of dry bone weight).
What are the four major cell types found in bone?
- bone lining cells
What are osetoblasts?
Bone cells responsible for formation and organization of the ECM of bone and its subsequent mineralization.
Osetoblasts are responsible for bone formation. What cells are osteoblasts derived from?
Osetoblasts are derived from mesenchymal cells. What three other tissue types can these cells develop into?
Osteoblasts function in proteolysis and polymerization of collagen to form the ECM of bone. What enzyme is involved in the mineralization of this matrix.
What are osetocytes?
Mature osteoblasts found within lacunae with extended protoplasmic processes in canaliculi in the intracellular matrix.
What are osteoclasts?
Large, multinucleated cells which function in bone resorption.
Osteoclasts are responsible for bone resorption. What cells are osteoclasts derived from?
Osteoclasts are responsible for bone resorption. What two ezymes found in osteoclasts are capable of degrading collagen?
- tartrate-resistant acid phosphatase (TRAP)
- cathepsin K (cysteine proteinase)
What are Howship’s lacunae?
Resorptive pits in which osteoclasts reside.
What three hormones are involved in the regulation of osteoclasts?
- parathyroid hormone (PTH)
- calcitriol (vitamin D3)
Bone resorption cannot take place without osteoblasts. True or false?
True: PTH stimulates osteoblasts to activate osteoclast precursors to differentiate into osteoclasts through RANKL/RANK interaction.