Lesson 3 Flashcards
What is the process of bone hardening called?
Calcification
What is calcification?
Bone hardening
What is the difference between calcification and ossification?
Calcification is the process of bone hardening
and is a part of ossification
Ossification is the process of bone development
What is ossification?
The process of bone development
What is the process of bone development called?
Ossification
When does bone start to develop?
Around the 6th week of embryonic development
What is formed around the 6th week of embryonic development?
A mesenchymal skeleton
What is a mesenchymal skeleton?
Embryonic connective tissue
What are the 2 types of ossification?
Intramembranous
Endochondral
What is the difference between intramembranous and endochondral ossification?
Intramembranous ossification: mesenchymal skeleton becomes bone
Endochondral ossification: mesenchymal skeleton becomes hyaline cartilage which becomes bone
Which type of ossification involves the mesenchymal skeleton developing into hyaline cartilage then bone?
Endochondral
Which type of ossification involves the mesenchymal skeleton directly developing into bone?
Intramembranous
The skull’s flat bones, most facial bones, the mandible, and the clavicle’s medial part form through ___ ossification
Intramembranous
What bones form through intramembranous ossification?
The skull’s flat bones, most facial bones, the mandible, and the clavicle’s medial part
What is the process of intramembranous ossification?
1) Mesenchymal stem cells cluster and change into osteogenic cells which change into osteoblasts all with the help of a blood supply
2) Calcification by which osteoblasts secrete ECM and osteocytes form
3) Trabeculae/spongy bone develop and in utero and juvenile these bones are populated by the red bone marrow
4) Periosteum develops
In intramembranous ossification, what cells do mesenchymal stem cells cluster and change into?
Osteogenic cells
In intramembranous ossification, what bone marrow are spongy bones in utero and juvenile populated by?
Red bone marrow
In endochondral ossification, what cartilage does the mesenchymal skeleton develop into?
Hyaline
What type of ossification do most bones of the body form through?
Endochondral
Most of the bones in the body including long bones, various regions of the thorax, and some parts of the skull form through ___ ossification
Endochondral
What is the process of endochondral ossification?
1) Chondroblasts secrete cartilage
2) A bony collar surrounding the cartilage keeps the cartilage upright allowing it to grow in length and width and blood vessels move into the middle of it through the nutrient foramina forming the primary ossification center
3) The primary ossification center develops into the medullary cavity from osteoblasts secreting osteous tissue and osteoclasts breaking down the cartilage and bones formed previously from the POC
4) At the time of birth, epiphyseal vasculature moves towards bone extremities forming the secondary ossification center at both ends of the bone
5) Articular cartilage and epiphyseal plate/metaphyseal region form
What do chondroblasts do?
Secrete cartilage
What cells secrete cartilage?
Chondroblasts
In endochondral ossification, what is the perichondrium replaced by?
The periosteum
In endochondral ossification, what does the periosteum come from?
The perichondrium
In endochondral ossification, what does the bony collar come from?
Intramembranous ossification
In endochondral ossification, what does the bony collar do?
It surrounds hyaline cartilage keeping it upright allowing it to grow in length and width
When bones grow in length what is it called?
Interstitial growth
When bones grow in width what is it called?
Appositional growth
In endochondral ossification, how is the primary ossification center made?
Chondroblasts secrete cartilage–> a bony collar surrounds it allowing it to grow –> blood vessels move into the middle of it through the nutrient foramina–> POC
In endochondral ossification, how do blood vessels move into the middle of the hyaline cartilage to form the primary ossification center?
Through the nutrient foramina
In endochondral ossification, what does the primary ossification center develop into?
The medullary cavity
In endochondral ossification, how does the medullary cavity form from the primary ossification center?
From osteoblasts secreting osteous tissue and osteoclasts breaking down the hyaline cartilage
In endochondral ossification, what does the secondary ossification center develop into?
Articular cartilage and epiphyseal plate/metaphyseal region
In endochondral ossification, how is the secondary ossification center made?
Chondroblasts secrete cartilage–> a bony collar surrounds it allowing it to grow –> blood vessels move into the middle of it through the nutrient foramina–> POC–> osteoblasts and osteoclasts make the medullary cavity–> epiphyseal vasculature moves toward bone extremities–> SOC
In endochondral ossification, when does epiphyseal vasculature move towards bone extremities?
At the time of birth
In endochondral ossification, where does the secondary ossification center formed?
At both ends of the bone/ephiphyses
In endochondral ossification, where does the primary ossification center formed?
In the middle of the bone/diaphyses
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