W28-L6: Histology of bones and joints Flashcards
What is hyaline cartilage made of?
Collagen type II and ground substance (GAGs etc.)
What cell maintains hyaline cartilage?
Chondrocytes
What is elastic cartilage?
Hyaline cartilage with the addition of elastin
What is fibrocartilage?
Mixture of dense fibrous connective tissue and isolated islands of cartilage (Type 1 collagen)
What is the structure of trabecular bone?
Open structure braces joints, which are continuous, constructed of lamellae
What is the difference between yellow and red marrow?
Yellow is mainly fat cells, red marrow is mainly haemopoietic cells
What are the blood vessels in the medullary cavity?
Sinusoids instead of capillaries
What are the layers of the periosteum?
Outer fibrous layer and inner cellular layer (osteoprogenitor cells)
What are sharpey’s fibres?
where there is no periosteum or endosteum
as tendon is actually
penetrating bone and interacts with bone ECM
What is the blood supply of bone?
Arteries supply bones at a number of discrete points
How do arteries supply the parts of bones?
Branch in marrow cavity, then separate supply to diaphysis, epiphysis and periosteum
Where do nerves run in bones?
Follow blood vessels, bones are densely innervated
What is the structure of articular cartilage?
No periosteum here, hyaline cartilage forms surface but there is no perichondirum (so damage causes issues with repairs)
Is the synovial membrane an epithelium?
No as it lacks a basement membrane, tight junctions so very leaky
What is the synovial surface layer?
two to three cells thick mix of fibroblast and macrophage like cells
What is the sub-intimal layer?
where synovial fluid moves from through the synovial membrane (which is leaky) into synovial space
What are Haversian canals?
Foramen that carry the blood vessel that is surrounded by a haversian system which is a metabolic system reliant on that vessel
Where are osteoprogenitor cells?
In periosteum and endosteum, usually resting or quiescent
How do osteoblasts make new bone?
Makes osteoid (collagen type I)
What are osteocytes?
Cells that livewithin the bone, as osteoblast entombs itself with bone, maintains immediate bone around itself
How do osteocytes gain nutrients?
connected to each other by tiny little tubes from one that is connected to a blood vessel
How do osteoclasts break down bone?
Secrete H+, Cl- and proteases
What is a marker of osteoclast activity?
Tartrate-resistant acid phosphatase
During development how is bone laid down?
Membrane bone or endochondral bone
How does membrane bone form?
Directly from mesoderm/mesenchyme eg skull and clavicle
How do weight bearing bones and bones of extremities form?
Endochondral ossification
How does endochondral ossification work?
Cartilage model is replaced by bone (not cartilage into bone though)
How does cartilage get replaced by bone in endochonral ossification?
Bone collar forms around diaphysis, cartilage beneath then degenerates
How do growth plates work?
on the edges of the growth plate cartilage is replaced by bone, most bone extension happens on diaphysis side
What is woven bone?
New bone that is more cellular, more collagen and no haversian systems
How are haversian systems built?
Osteoblasts lay layers of bone with the collagen alternating in direction
