Bio Final Bones
osteoclasts
bone cells that break down and reabsorption of the material
extracellular matrix
a collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells
Structure of epiphyseal plate
a layer of hyaline cartilage located in the metaphysis of growing bone that has 4 zones
calcium concentration in blood plasma
9.2-10.4 mg/dL
parathyroid hormone
A hormone that regulates the metabolism of calcium and phosphorus in the body, promotes calcitrol synthesis
development of primary ossification center
A nutrient artery penetrates the center of the cartilage model and stimulates mesenchyme to mature into osteoblasts Osteoblasts will form a periosteum around the model and spongy bone trabeculae in the center of the cartilage model, now the primary ossification center. Ossification spreads toward the ends of the model.
growth of cartilage model
Chondroblasts are now called chondrocytes. Chondrocytes increase in size and secrete extracellular matrix, Cartilage begins to calcify and die
zone of hypertrophic cartilage
Large, mature chondrocytes that are arranged in columns
zone of resting cartilage
Layer closest to end of epiphysis, Resting cells, anchor epiphyseal plate to epiphysis
calcitonin
Lowers blood calcium levels
Rickets
Vitamin D deficiency causing bones to become soft
bone deposition
addition of minerals and collagen fibers to bone by osteoblasts
Perferating canals (Volkmann's canals)
blood vessel path through osteon
zone of bone deposition
breakdown of lacuna walls, leaving open channels; death of chondrocytes; bone deposition by osteoblasts, forming trabeculae of spongy bone
osteoblasts
build bone
hormones present at bone deposition
calcitonin
bone elongation is due to
cartilage growth
what is common to find in compact bone but not in spongy bone
central canals
zone of cell hypertrophy
cessation of mitosis; enlargement of chondrocytes and thinning of lacuna walls
zone of cell proliferation
chondrocytes multiplying and lining up in rows of small flattened lacunae
concentric lamellae
circular plates of mineralized extracellular matrix of increasing diameter, surrounding a small network of blood vessels and nerves located in the central canal
osseous tissue
connective tissue made of bone
spongy bone tissue
consists of an irregular latticework of thin plates of bone called trabeculae, with spaces in-between filled with red bone marrow
Hypocalcemia
deficient calcium in the blood
reactive phase of bone repair
early inflammatory phase where a hematoma forms
thyroid hormone
enhances synthesis of growth hormone
development of secondary ossification center
epiphyseal artery enters epiphyses and bone formation begins
Hypercalcemia
excessive calcium in the blood
reparative phase of bone repair
formation of a fibrocartilaginous callus by chondroblasts and then a bony callus forms from osteoblasts producing spongy bone trabeculae
zone of proliferating cartilage
function in interstitial growth, chondrocytes are stacked on each other in columns and they divide and secrete extracellular matrix
medullary cavity
hollow space in the diaphysis that contains yellow bone marrow and blood vessels
growth hormone
hormone secreted by anterior pituitary gland that stimulates growth of bones by increasing excretion and absorption of ca2+
formation fo articular cartilage and epiphyseal plate
hyaline cartilage becomes articular cartilage
articular cartilage
hyaline cartilage that covers the epiphysis of the bone
cortisol
inhibits osteoclasts and in excess cause osteoporosis by stimulating osteoclasts
bone remodeling phase of bone repair
last step as the bony callus is remodeled
central canal
location of blood vessels and nerves within an osteon
osteocytes
mature osteoblasts that have trapped themselves in extracellular matrix and are responsible for metabolism in the bone
Endosteum
membrane that lines the medullary cavity
development of cartilage model
mesenchymal cells develop into chondroblasts, which form the cartilage model
what is the zone of the epiphyseal plate where in children and adolescents bone can be seen replacing cartilage
metaphysis
bone remolding
on going replacement of old bone with new bone
bone formation
ossification or osteogenesis
which bone cell has the greatest amount of lysosomes
osteoclasts
Development of the medullary cavity
osteoclasts break down newly formed spongy bone and leaves a cavity
Blood Ca2+ deficiency stimulates __________ secretion, which leads to _____________.
parathyroid hormone, increased osteoclast activity
endochondral ossification
process in which bone forms by replacing hyaline cartilage
Calcitrol
promotes intestinal absorption of ca2+ and stimulates osteoclasts
Epiphysis
proximal and distal ends of the bone
canaliculi
radiate from lacunae and contain extracellular matrix
The process of dissolving bone and returning its minerals to the bloodstream is known as
repsorption
Diaphysis
shaft of the bone
lacunae
small cavities in bone that contain osteocytes
osteomalacia
softening of the bone in adults due to lack of blood calcium
spicules and trabeculae are found in
spongy bone
epiphyseal plate is present at
step 5 of endochondral ossification
insulin
stimulates bone formation
Testosterone
stimulates osteoblasts and promotes protein synthesis
estrogen
stimulates osteoblasts in adolescents, prevents osteoporosis
osteons
structural unit of compact bone
Function of bones
support, movement, protection, mineral storage, blood cell formation, energy metabolism
zone of calcification
temporary calcification of cartilage matrix between columns of lacunae
bone resorption
the removal of minerals and collagen fibers from bone by osteoclasts and released into the bloodstream
zone of calcified cartilage
thin layer of dead cartilage cells and calcified matrix
periosteum
tough protective sheath that covers the bone
zone of reserve cartilage
typical histology of resting hyaline cartilage
osteoprogenitor cells
undifferentiated bone stem cells that undergo mitosis and are the source of new osteoblasts
