Bone is (vascular/avascular) and cartilage is (vascular/avascular).
Bone is vascular
Cartilage is avascular
What is the embryonic germ layer that gives rise to bone and cartilage?
Bone contains what type of collagen?
Collagen type 1
Cartilage contains what type of collagen?
Collagen type 1, 2
What type of growth does bone exhibit?
Appositional (from the surface out)
True/False: Cartilage only grows appositionally.
False, cartilage grows both appositionally and interstitially.
What are the three types of bone?
Compact, cancellous (spongy), woven
What are the three types of cartilage?
Hyaline, elastic, fibrocartilage
A woman has an infection in the center of the epiphysis of a long bone causing damage to spicules of bone. This damage involves which type of bone?
What are the three cell types in bone?
What is the origin of osteoblasts and osteocytes?
Osteocytes lie in what small fluid filled spaces?
Osteoclasts have what precursor?
Related to monocytes/macrophages
What cell type of bone is multinucleated?
Where are osteoblasts found?
Endosteum and periosteum
What is the shape of osteoblasts?
Stellate (star shape)
Osteoblasts are (basophilic/eosinophilic).
Basophilic (due to large amount of RER)
What are the functions of osteoblasts?
1. Stimulate osteoclasts (via factors)
2. Make bone
3. Become osteocytes
What is an important blood marker of bone synthesis?
Bone synthesis requires what vitamin?
Vitamin C (osteoblasts are making matrix protein - collagen type 1 - requires Vit C)
What are the bone matrix proteins made by osteoblasts (other than collagen type 1)?
Osteocalcin (binds calcium - hydroxapatite)
The initial substance (early bone) formed by osteoblasts is called...?
(mineralization of osteoid makes bone)
What is the origin of osteocytes?
Osteoblasts become osteocytes
What are the important characteristics of osteocytes?
Located in lacunae
Processes in canaliculi (gap junctions)
Periosteocytic space (calcium resorption)
Not very active (small Golgi and RER)
NON-dividing (NO interstitial growth)
What are the functions of osteocytes?
Osteocytic osteolysis (regulates plasma Ca2+)
Mechanotransduction: Pull or push, recruit pre-osteoblasts
What is the origin of osteoclasts?
Hematopoetic stem cells (bone marrow GM-CFU)
What are the characteristics of osteoclasts?
Large, motile, multinucleated, acidophilic (pink staining)
Ruffled border (absent in Osteopetrosis)
Many mitochondria, Golgi, Lysosomes, RER
What is the function of osteoclasts?
-mineral then collagen and other protein
-too much osteoclast activity = osteoporosis
Where does mineral dissolution by osteoclasts occur?
Outside the ruffled border
Describe the environment of mineral dissolution by osteoclasts.
Lysosomal enzymes and acid environment
Carbonic acid (low pH) dissociates into H+ ions
Na+/H+ antiporter (both are active transport)
A man breaks his arm. During healing, new bone is built. Which cell is responsible for this building?
Describe the microanatomy of an osteon.
Haversian canal (blood vessels and nerves, lined by endosteum - osteoprogenitor cells)
Cement line is the outermost boundary of osteon (lacks canaliculi)
Concentric lamellae around osteon
A person develops osteoporosis because too many resorption tunnels are made by osteoclasts. Following treatment, osteoblasts fill in these tunnels, adding the youngest concentric lamella...where?
Nearest to the Haversian canal (bone is formed from the wall in)
What are the 4 basic blood supply sources of bone?
What type of bone contain trabeculae and spicules?
Cancellous (spongy) bone
Describe cancellous bone.
Lined by endosteum
Bounds epiphyseal plate
1. Are located in the center of spicules
2. Contain osteoblasts in lacuna
3. Are found in compact bone
3. Are found in compact bone
What is the connective tissue that covers bone?
True/False: Periosteum is active in children and resting in adults.
True, because children are growing bone diameters.
What are the two layers of periosteum?
1. Inner cellular layer (osteoprogenitor cells - for bone repair)
2. Outer fibrous layer (dense fibrous connective tissue, contiguous with joint capsules)
What are Sharpey's fibers?
Fibers that connect periosteum to bone
What type of cartilage is found in the embryonic skeleton?
Where is fibrocartilage found?