Table of Contents
- 1 At which region of the epiphyseal plate are dead chondrocytes and calcified matrix being replaced by bone?
- 2 What type of cell breaks down the calcified extracellular matrix in developing bones?
- 3 What is epiphyseal growth plate?
- 4 What is the extracellular matrix composed of in cartilage?
- 5 How does the zone of calcified cartilage become New diaphysis?
At which region of the epiphyseal plate are dead chondrocytes and calcified matrix being replaced by bone?
The longitudinal growth of bone is a result of cellular division in the proliferative zone along with the maturation of cells in the zone of maturation and hypertrophy. The zone of calcified matrix, the zone closest to the diaphysis, contains chondrocytes that are dead because the matrix around them has calcified.
What cell is calcified in the epiphyseal plate?
osteoblasts
Histology
| Epiphyseal plate zone (from epiphysis to diaphysis) | Description |
|---|---|
| Zone of calcification | Chondrocytes undergo apoptosis. Cartilagenous matrix begins to calcify. |
| Zone of ossification | Osteoclasts and osteoblasts from the diaphyseal side break down the calcified cartilage and replace with mineralized bone tissue. |
What are the four layers of the epiphyseal plate?
Terms in this set (4)
- Layer closest to epiphysis; where cartilage remains. Resting zone.
- Chondrocytes producing new cartilage cells. Proliferating zone.
- Cartilage cells are dying off. Degenerating zone.
- Zone where bone is forming. Ossification zone.
What type of cell breaks down the calcified extracellular matrix in developing bones?
Osteoclasts
Osteoclasts are large bone cells with up to 50 nuclei. They remove bone structure by releasing lysosomal enzymes and acids that dissolve the bony matrix.
Which region of a growing bone contains epiphyseal plate?
metaphysis
Each epiphysis meets the diaphysis at the metaphysis, the narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline (transparent) cartilage in a growing bone.
What are layers of calcified matrix?
6 Guide Questions
| Question | Answer |
|---|---|
| layers of calcified matrix | concentric lamellae |
| residence of osteocytes | lacunae |
| canal that carries blood vessels and nerves | central canal |
| nonliving structural part of bone | bone matrix |
What is epiphyseal growth plate?
The epiphyseal growth plate is the main site of longitudinal growth of the long bones. At this site, cartilage is formed by the proliferation and hypertrophy of cells and synthesis of the typical extracellular matrix. The formed cartilage is then calcified, degraded, and replaced by osseous tissue.
What are the growth plate zones?
The chondrocytes in the growth plates are surrounded by matrix consisting of proteoglycan aggregates and are divided into three zones, reserve/resting zone, proliferative zone and hypertrophic zone.
What is the layer of the epiphyseal growth plate?
hyaline cartilage
The epiphyseal plate is the area of growth in a long bone. It is a layer of hyaline cartilage where ossification occurs in immature bones.
What is the extracellular matrix composed of in cartilage?
II collagen
Cartilage extracellular matrix (ECM) is composed primarily of the network type II collagen (COLII) and an interlocking mesh of fibrous proteins and proteoglycans (PGs), hyaluronic acid (HA), and chondroitin sulfate (CS).
Why are chondrocytes dead in the epiphyseal plate?
+epiphyseal plate is only a few cells thick and consist mostly of chondrocytes that dead because the extracellular matrix around them has calcified +osteoclasts dissolve the calcified cartilage +osteoblasts and capillaries from the diaphysis invade the area
What happens when bone replaces the epiphyseal plate?
+the epiphyseal plates close. The epiphyseal cartilage cells stop dviding, and bone replaces all of the cartilage. The epiphyseal plate fades, leaving a bony structure called the epiphyseal line
How does the zone of calcified cartilage become New diaphysis?
+ as a result the zone of calcified cartilage becomes new diaphysis that is firmly cemented to the rest of the diaphysis of the bone As a bone grows +new chondrocytes are formed on the epiphyseal side of the plate, while old chondrocytes on the diaphyseal side of plate are replaced by bone
What is the epiphyseal plate layer of hyaline cartilage?
Epiphyseal plate Layer of hyaline cartilage in the metaphysis of a growing bone that consist of four zones +zone of resting cartilage +zone of proliferating cartilage +near to the epiphysis +consist of small, scattered chondrocytes + this layer consists of slightly larger chondrocytes arranged like stacks of coins.