Cartilage and bone Flashcards
What are the features of cartilage?
Semi-rigid and strong but slightly flexible
Withstands compression forces such as weight-bearing but can also bent
It has a major role during development and growth of long bones
Avascular
What is meant by avscular?
little or no blood vessels
What is the significance of blood vessels being avascular?
The cells in the cartilage have to get their oxygen and nutrients by long range diffusion
What are the cells of cartilage?
Chondrocytes
What do chondrocytes originate as?
Develop from chondroblasts
What is the role of chondrocytes?
Produce the extracellular matirx
Where are chondrocytes located
Within matrix enclosed compartments (lacunae)
What are the three types of cartilage?
Hyaline
Elastic
Fibrocartliage
Where is hyaline cartilage found?
Articular surfaces of bones
Trachea and bronchus
Costal cartilages
Nasal cavity & nose
Where is elastic cartilage found?
Pinna of external ear
Epiglottis
Where is fibrocartilage found?
Tendon insertions
Pubic symphysis
Intervertebral discs
Articular menisici
What does the matrix of hyaline cartilage comprise of?
Collagen type II fibres embedded in a firm hydrated gel of proteoglycans and structural glycoproteins
What does elastic cartilage have in abundance?
elastic fibres
What is fibrocarttilage?
Intermediate between dense irregular CT and hyaline cartilage
Describe the arrangements of chondrocytes
Arranged in straight rows separated by collagen type 1 fibres
What is the role of fibrocartilage?
Combines tensile strength with shock absorption and resists compression
What is the role of bone?
Protects internal organs Stores and releases fat Produces blood cells Stores and releases minerals Facilitates Movement Supports the body
What does the bone matrix consist of?
Collagen type I - 95% of organic matrix
How does the matrix harden?
The binding of calcium phosphate in the form of hydroxyapatite crystals which surround fibres
What are the three types of bone cells?
Osteoblasts
Osteoclasts
Osteocytes
What is the role of osteoblasts?
Form bone matrix and respnsible for the production of the ECM
What is the role of osteocytes?
Maintain bone matrix
Principle bone cell of the adult skeleton
What is the role of osteoclasts?
Resorb bone caused by releasing enzymes
What is an osteoid?
The unmineralised component of bone
Where are osteoblasts located?
Exclusively located at the surfaces of bone tissue
How do osteoblasts become osteocytes?
Gradually surrounded by matrix and become trapped in matrix
Where do osteoblasts originate?
Develop form an osteoprogenitor cell
Where are osteocytes found?
lacunae
How do lucanae connect to each other?
Through small channels called canaliculi
What does the canaliculi allow?
Allows the flow of nutrients and oxygen through the matrix
Where do osteoclasts derive from?
The monocyte phagocyte line
Describe the shape of osteoclasts
Very large, motile cells
multinucleate
highly folded forming a ruffled border
Where are the osteoclasts located?
Sit on bone surface often in depression called howships lacunae
What are the two types of bones?
Compact (cotical)
spongy (trabecular/cancellous)
What does compact bone comprise of?
Collagen fibres arranged in concentric lamellae around and canal containing blood vessels and nerves (osteon/haversion system)
What does spongy bone comprise of?
Bone organised into plates of bone called trabeculae/spicules
Lamellae in trabeculae are arranged concentrically- however there is no central canal
Osteocytes- that sit in lacunae between lamellae
Trabeculae sit adjacent to red marrow spaces
What is periosteum?
Dense irregular CT cover outer surface of bone
Contains osteoprogenitor cells
How does periosteum bind ot bone?
Through bundles of collagen fibres penetrating the bone matrix
What is endosteum?
single layer of osteoprogenitor cells and a very small amount of CT
What is the main function of periosteum or endosteum?
Provide nutrients to bone tissue and provision of new bone cells
