Cartilage, Bones, and Joints Flashcards
Chondrocytes
component of cartilage. Live in lacunae. Secrete matrix.
What is in cartilage?
there are no vessels or nerves, so nutrients must diffuse in. Cannot be a source of pain
Types of Cartilage Growth
- appositional
2. interstitial
Appositional Growth
expansion from periphery. Continues throughout life. From perichondrium. Source of stem cells
Perichondrium
outer layer of cartilage responsible for appositional growth.
Does articular cartilage have a perichondrium?
no, so it cannot continue growing
Interstitial Growth
expansion from within. Matrix and cell numbers increase. result in isogenous group. Most important in young animals
Isogenous Group
multiple cells in a cluster, characteristic of interstitial growth
Types of Cartilage
- Hyaline
- Elastic
- Fibrocartilage
Hyaline Cartilage
glassy. Found in fetal skeleton and articular surfaces of bone
Locations of Hyaline Cartilage
respiratory tree- nose, larynx, trachea
Elastic Cartilage
has elastic fibers between chondrocytes.
How to visualize elastic fibers in elastic cartilage?
cannot see on routine stain, need elastin stain
Locations of Elastic cartilage
pinnae, external ear canal
Fibrocartilage
cartilage mixed with dense collagen. Chondrocytes are in rows
Locations of Fibrocartilage
menisci, intervertebral discs, tendon and ligament attachments to bone
Components of bone
cells and matrix
Types of bone cells
osteoblasts, osteocytes, and osteoclasts
Osteoblasts
produce bone. Polygonal cells in rows along bone surface. Secrete and mineralize osteoid
Osteoid
unmineralized bone
Osteocytes
embedded osteoblasts. Live in lacunae. Communicate with each other
Osteoclasts
remove bone. Multinucleated giant cells of bone marrow origin. Bone removal occurs along brush or ruffled border.
Howship’s Lacunae
depression in bone formed by osteoclast
Types of Matrix
mineral and collagen
Mineral Matrix
the majority of the bone is mineral. Mineral gives bone its rigidity
Hydroxyapatite Crystal
calcium and phosphorus in a 5:3 ratio
Collagen Matrix
polarized light required to see collagen. Gives bone its tensile strength.
Microscopic Organization of Bone Collagen
woven bone and lamellar bone
Woven Bone
immature bone. Formed during growth and repair. haphazardly arranged collagen fibers
Lamellar Bone
mature bone. Parallel collagen fibers.
Osteon
cylinders of concentric lamellae. Haversian canals at center of osteon. Blood vessels and nerves within canal. Stronger than woven bone
Configuration of Bone
compact bone and cancellous bone
Compact Bone
solid bone with minimal marrow. Can be woven or lamellar. Cortex of adult bone is compact lamellar
Cancellous Bone
Trabeculae arranged in a 3 dimensional lattice. More bone marrow spaces than compact bone. Can be woven or lamellar. Present inside bone medullary cavity
Epiphysis
end of bone, covered with articular cartilage
Physis
clear line. Growth plate made of cartilage only present in growing animals
Metaphysis
cone-shaped transition between diaphysis and epiphysis
Diaphysis
cylindrical shaft of bone that contains nutrient foramen
Nutrient Foramen
opening for blood vessel to come in in bone
Marrow
contains hematopoietic cells. Becomes increasingly fatty with age
Periosteum
fibrous outer bony envelope. contains osteoprogenitor cells. Involved in repair and remodeling
Where does osteosarcoma occur
in metaphysis
Endosteum
inner bony envelope
Types of Ossification
- endochondral ossification
2. intramembranous ossification
Endochondral Ossification
replacement of hyaline cartilage template by bone. Bone formation within cartilage
Layers of Physis inEndochondral Ossification
- Resting chondrocytes
- Proliferating chondrocytes that look like stack of coins
- Hypertrophied chondrocytes. Cells are swollen. Weakest zone
Osteoid
mineralized to form woven bone which covers remaining cartilage cores
Salter-Harris Fractures
Fractures in physis. Affect bone growth in young animals
Intramembranous Ossification
replacement of mesenchymal template by bone. Bone forms from condensed mesenchymal cells. Cartilage is not involved
What determines bone density?
weight bearing
Types of Joints
- fibrous
- cartilaginous
- synovial
Fibrous Joints
bones connected by dense collagen
Cartilaginous Joints
bones connected by fibrocartilage
Synovial Joints
ends of bones covered by hyaline cartilage. Bones connected by ligaments (attached to bone by fibrocartilage) and fibrous joint capsule.
Synovial Membrane
Lines the inside of joint and inside of tendon sheaths.
Synoviocytes
produce synovial fluid
Synovial Fluid
lubricates joint (very viscous)