Bone & Cartilage Flashcards
What is the primary cell for bone formation?
Osteoblasts
What does Osteoblasts create?
Osteoid - unmineralised bone matrix
Matrix Vesicles - which create enzymes to increase calcification
What type of collegen doses Osteoid contain?
Type 1
Give an example of a glycoprotein found within the Osteoid?
Osteocalcin
What is Osteomalacia?
Poor mineralisation or bones.
What are the 2 types of Ossification?
Intramembranous
Endochondral
What are Osteoblasts?
Responsible for the formation of bone by way of collagen fibers, proteoglycans and glycoproteins. Active cells
What are Osteocytes?
These are the maintaining bone cells. These are trapped within the matrix and look after the regulation of calcium.
What are Osteoclasts?
These are the cells that destroy, additional over production of bone. Sit on the bone surface.
What bones does Intramembranous Ossification make?
Flat bones
Where does the Intramembranous Ossification take place?
In the Mesenchymal cell membrane which surrounds the bone.
What is the 1st stage of Intramembranous Ossification?
When the Meschymal cells differentiate and become Osteoblasts.
These then duplicate and form Ossification center.
This center then produces Osteoid.
What is the 2nd stage of Intramembranous Ossification?
The Osteoid becomes mineralised creating an ‘island of bone’ and the odd osteoblast becomes trapped creating an osteocyte.
What is the 3rd stage of Intramembranous Ossification?
These islands of bone then join up creating an trabeculae, where blood vessels weave into.
Also the meschymal cells now become denser forming a sheath called a Periostium.
What is a periostium?
A connective tissue sheath covering bones formed from Mesenchymal cells that have changed to become fibroblasts..
What is a Trabeculae?
Where ‘Islands of bone’ join.
What is the 4th stage of Intramembranous Ossification?
This is where the otter bone becomes compact bone while the inner bone remains spongy.
Red marrow develops internally.
How many stages is there to Endochandral ossification?
5 stages
How does endochondral ossification differ from Intramendous ossification?
Endo Oss - starts with a cartilage template and fills in with bone.
Intra Oss - spreads out from Osteoblast masses known as ossification centers.
How is the Cartilage template made?
By Mesenchymal tissue, which change to Chodrocytes.
What are the two areas of the long bone called?
Diaphysis - the shaft
Epiphyses - the club shaped ends.
What is the 1st stage of Endochondral Ossification?
The central cartilage cells of the Diaphysis die, leving gaps. The Pericondrium (covering) cells around the diaphysis (shaft) create Osteoblasts and start Intramembrous ossification!!
What is the 2nd stage of Endochondral Ossification?
The central bone cavity continues to get bigger.
The bone collar gets thicker.
BUT, the present cartilage contines to grow at a greater rate than the osteblasts can lay osteoid cause growth/length.
What is the 3rd Stage of Endochondral Ossification?
Capillaries come through the bone collar into the center releasing young osteoblasts, which form a primary ossification center.
Bone is now laid down where the cartilage once was.
