U2 Lecture 4 Flashcards
- describe interstitial and appositional growth of cartilage - describe how the presence of an epiphyseal plate facilitates the lengthening of bones - describe how remodeling is involved in growth and in maintaining bone shape - Describe the process of appositional growth and the role of the osteoblasts and osteoclasts in changing bone diameter, cortical width and medullary cavity size
1
Q
Types of growth of cartilage
A
Interstitial and appositional growth
2
Q
Define interstitial growth
A
- growth from within (cartilage)
- growth in length at epiphyseal plate
3
Q
Steps of interstitial growth
A
- Chondroblasts build matrix and differentiate into chondrocytes
- Chondrocytes divide
- chondrocytes build matrix and spread apart
- Cartilage tissue grows from within
4
Q
Zones for growth in the epiphyseal plate
A
Epiphysis
- resting cartilage
- proliferating cartilage
- hypertrophic cartilage
- calcified cartilage
Diaphysis
- epiphysis and diaphysis are the outer layers of bone
5
Q
What zone of cartilage is new chondrocytes formed?
A
proliferating cartilage
6
Q
What happens in calcified cartilage?
A
old chondrocytes are replaced by bone
7
Q
Growth at epiphyseal plate summary
A
- Diaphyseal osteoclasts break down calcified cartilage
- osteoblasts lay down spongy bone
- chondrocytes will continue to form cartilage matrix at the proliferating cartilage region
- growth in length stops when the osteoclasts/ osteoblasts work faster than the chondrocytes in the proliferating zone -> epiphyseal plate closes and becomes the epiphyseal line
8
Q
Define Appositional growth
A
- growth in width
- periosteal osteoblasts build bone on outer surface of bone and endosteal osteoblasts increase the diameter of the marrow cavity
- both bone diameter and cortical width increase
9
Q
What does appositional growth do?
A
It generates new osteons to the periosteal side of the bone
10
Q
Steps of appositional growth
A
- ridges in periosteum create groove for periosteal blood vessel
- periosteal ridges fuse, forming an endosteum-lined tunnel
- osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel forming a new osteon
- bone grows outward as osteoblasts in periosteum build new lamellae. repeats as ridges fold over blood vessels
