Ossification And Bone Structure Flashcards
(21 cards)
Label the bone…
What is intramembranous ossification?
This happens in the skull bones and is when bone is laid down to replace fibrous connective tissue.
What is endochondral ossification?
This is where hyaline cartilage is gradually replaced by osteocytes and it occurs in long bones, vertebrae and the pelvis.
What is the first step of endochondral ossification?
The outline structure of the bone is formed from cartilage.
What is the 2nd step of endochondral ossification?
Osteoblasts in the centre start to turn the model into bone.
What is the 3rd stage of endochondral ossification?
Secondary areas in the epiphysis start to become bone.
What is the 4th step of endochondral ossification?
Gradually the entire model is replaced by bone except the articular cartilage at the epiphyses and physis.
What are the two ways bones can develop?
Intramembranous ossification
Endochondral ossification
What do the following do….
Osteocytes
Osteoblasts
Osteoclasts
Osteocytes- inactive bone cell
Osteoblasts- produces new bone
Osteoclast- resorb old bone (destroy)
How do bone cells work in balance to maintain bone strength and blood calcium levels?
When blood calcium levels are high osteoblasts create new bone to store excess calcium. When blood calcium levels are low, osteoclasts break down bone to release calcium into blood circulation.
What is cortical bone?
Solid bone forming the outside of bone.
What is cancellous bone?
Network of struts forming the inside of some bones (spongy bone).
What is the diaphysis?
The main shaft
What is the epiphysis?
The prominences forming the ends.
What is the metaphysis?
Joins the diaphysis and epiphysis.
What is the physis?
The growth plate
What is the medullary cavity?
Central cavity filled with bone marrow.
What are the 3 main steps of endochondral ossification?
1- the outline of the bone is formed by membranes with stem cells inside.
2- stem cells become osteoblasts and start producing bone
3- eventually the entire area becomes bone and the trapped osteoblasts become osteocytes
What is the ideal calcium phosphate ratio?
1:1:1 or 1:3:1
What are the 3 types of cartilage?
Hyaline
Fibrocartilage
Elastic
