Cartilage and Bone Flashcards
What type of cells are cartilage and bone derived from
undifferentiated mesenchymal cells in the embryo
What are the precursors of cartilage
Mesenchymal cells differentiate into chondroblasts which future differentiate into chondrocytes
What is mature cartilage composed of
i.e. cells, matrix, capsule
Cells - chondrocytes
Matrix - a dense glycosaminoglycan rich substance containing collagen and elastic tissue
Capsule - Fibrous collagen capsule known as the perichondrium
What are the 3 different forms of cartilage
Fibrous, elastic and hyaline
Where is hyaline cartilage found
supporting ‘rings’ of trachea
cartilage of the larynx
Where is elastic cartilage found
Epiglottis
Pinna of the ear
Where is fibrous cartilage found
Inter-vertebral discs
What does ‘GAG’ stand for
Glycosaminoglycan
In hyaline cartilage, what is the name of the pale staining hollows that chondrocytes are found within
lacunae
What happens when hyaline cartilage is compressed
It exudes water
Do chondrocytes clump or appear singularly within the matrix
usually clump
Which types of cartilage can you fracture
All of them!
How is bone synthesised
Osteoblasts synthesis a collagen rich matrix called osteoid. This mixes with crystals of hydroxyapetite to form osteocytes
What is the function of osteoclasts (cells also found in the bone)
continuous remodelling of bone throughout life
What is found in the centre of many layers of osteons making up bone
Haversian’s canal
What is found within Haversian’s canal
blood vessels and nerves
What is interstitial bone and where is it found
Between osteons. It is old, dead bone
What are bones surrounded with
A fibrous capsule called periosteum - contains undifferentiated cells, important in bone healing
What is the average size of an osteon (may only be applicable to single slide..)
220 um
What is a cement line
Surrounds an osteon. It seals off the osteon from surrounding neighbours
What is the role of filopodia
They make contact with adj. cells - movement of nutrients and oxygen
Why are some Haversian Canal’s larger than others
bone becomes thinner with age
Before new bone is formed and as older phone dies the canal widens
Most bone was once cartilage. What is the name of the process of direct differentiation into bone from mesenchyme
intra-membranous ossification
Why do osteoblasts stain dark purple with H&E
Because the cytoplasm contain ++nucleic acid (RNA)
What happens to osteoblasts when they have completed their task of laying down new bone
They are trapped within new bone and transform into osteocytes
What are osteoclasts and where do they differentiate from
They are macrophages and they differentiate from blood monocytes. They digest bone and allow it to be remodelled - allowing the release of Ca+ into the circulation. They are completely separate to osteoblasts and cytes
How can you distinguish osteoclasts from blasts
greater size, multi-nuclear, intense pink staining cytoplasm
Where are osteoclasts found
In depressions know as Howship’s lucunae
Why do osteoclasts stain intense pink
They contain lysosomal enzymes
What is mature cartilage composed of
i.e. cells, matrix, capsule
Cells - chondrocytes
Matrix - a dense glycosaminoglycan rich matrix containing collagen and elastic tissue
Capsule - Fibrous collagen capsule known as the perichondrium
Why are some Haversian Canal’s larger than others
bone becomes thinner with age
Before new bone is formed and as older bone dies the canal widens
How does hyaline cartilage receive its nutrients and oxygen
mostly by diffusion
What is the difference between the interior heads of the bone and the shaft of the bone
They have identical composition but the heads have large holes to decrease the overall weight of the bone
Once embedded in the matrix, can chondrocytes divide
Yes
What do osteoblasts synthesise
osteocalcin
What does Volkmann’s Canal do
It joins adj. osteons
