Bone and cartilage physiology and histology Flashcards
Describe the basics of cartilage
Semi-rigid, permeable, and deformable avascular tissue.
Describe the basics of bone
Rigid non-permeable tissue
What are the key components of cartilage?
Chondrocytes (chondroblasts when immature)
Extracellular matrix:
Water- 75%
Organic material- 25%
What are the two organic materials found in cartilage ECM?
Type II collagen- 60%
Proteoglycan aggregates- 40%
What is the role of proteoglycan aggregates in cartilage?
To attract water to help resist compression.
What are the three types of cartilage?
Hyaline- Blue/White and translucent
Elastic- Yellow
Fibrocartilage- Intermediate between hyaline and tendon.
Where is fibrocartilage found?
At the junction between tendons and bone.
What makes elastic cartilage unique?
Collagen is replaced with elastin.
Where can elastic cartilage be found?
Ear pinna etc
Where can hyaline cartilage be found?
Articular surfaces Tracheal rings Costal cartilage Epiphyseal growth plates Precursor to boney features
What does endochondral bone derive from?
A hyaline cartilage template.
How does endochondral bone form?
The diaphysis slowly ossifies and extends at the epiphyseal growth plate until the bone reaches its required length then the whole lot ossifies.
What are the 4 major parts of a growing endochondral bone?
Diaphysis- Shaft
Metaphysis- Area between diaphysis and epiphysis that contains the EGP
Epiphysis- End of bone
Epiphyseal growth plate- Area of growth and ossification.
What are the two types of bone?
Cortical- Compact, dense and strong.
Trabecular- Spongy, weaker and light.
What is hollow bone?
Bone with a cavity in the middle for bone marrow.
What are the two types of bone marrow?
Red- produces blood.
Yellow- Does not produce blood.
What is the periosteum?
A sheath of fibrous connective tissue surrounding bones. It is well vascularised and innervated.
What are the four chemical components of bone?
Water- 10%
Type 1 Collagen- 23%
Non-collagen proteins- 2%
Bioapatite- 65%
What is the basic unit of bone?
Osteon
What demarcates the outer boundary of the osteon?
Cement line
What is the endosteum?
Periosteum lining the inside of the bone.
Describe an osteon.
Compact tubes of layered bone running the length of the bone.
What is a Haversion canal?
A canal running down the middle of an osteon to supply it with blood etc.
What lies in the centre of an osteon?
A Haversion canal.
What is a Wolkmann’s canal?
A canal linking the Haversion canals of two osteons.
What links osteons?
Wolkmann’s canal.
Are osteocytes found in osteons?
Yes
How are osteocytes supplied?
Through tiny blood vessels leading off the Haversion canal. Works for up to 250microM.
What lines Haversion and Wolkmann’s canals?
Osteonal Endosteum.
What is the osteonal endosteum?
A continuation of the periosteum lining the Haversion and Wolkmann’s canals.
How does trabecular bone differ from cortical bone?
It lacks osteons as bone is a lot thinner.
What is bone remodelling?
The process by which bone is replaced.
Give an overview of bone remodelling.
Osteoclasts clump together and drill through bone.
Blood vessels form in its wake.
Osteoblasts travel through blood vessel and form new bone.
What do osteoblasts secrete to form new bone?
Collagen and osteoid (organic components) which mineralise.
What is woven bone?
Bone containing disorganised collagen that is fast to produce for healing and is then remodelled over time to laminar bone.
