Cartilage and Bone Flashcards
What are the skeletal tissues composed of?
bone and cartilage
Which feature is common to all cartilages?
it has no blood vessels -avascular
What are the types of cartilage?
hyaline cartilage, fibrocartilage, elastic cartilage
What is the ground substance in cartilage made from predominantly?
the ground substance is chondroitin sulphate (GAG). functions to provides resistance to compression
What are the cells of cartilage?
chondrocytes and chondroblasts
What are the unique properties of cartilage ECM?
The ECM of cartilage unlike other tissues is firm, solid, and glassy.
Describe hyaline cartilage
most common cartilage, abundant ground substance. smooth, gel like tissue that is perfect for lubricating joints, at the end of all long bones, and ribs. very tough and flexible and has significant compression strength.
What is the perichondrium?
a dense connective tissue that surrounds hyaline cartilage and elastic cartilage externally
Articular cartilage is a modification of which other type of cartilage?
hyaline
How does cartilage receive nutrients?
Since there is no direct blood supply, chondrocytes receive nourishment via diffusion from the surrounding environment.
Describe elastic cartilage
flexible, provides support and resistance to compression
Highly flexible, Outer ear/epiglottis
Histologically similar to hyaline cartilage
Elastin fibres concentrated around lacunae. Collagen fibres are also present
What is lacunae in cartilage?
small chamber in the matrix occupied by one or more chondrocytes
Describe fibrocartilage
Extremely durable and tough
Little ground substance
Dominated by irregular dense collagen fibres
Chondrocytes arranged in rows
Pads lie between spinal vertebrae, pubis, knee
Which type of cartilage is dominated by dense bundles of collagen fibres?
fibrocartilage
What does the ground substance of bone consist of?
Chondroitin sulphate
Hyaluronic acid
What are the fibres in bone?
type 1 collagen
What is the name of the organic unmineralised component of bone ECM?
osteoid
What is the extracellular matrix in bone?
made up of organic matrix (30%) and hydroxyapatite (70%)
Before the ECM is calcified it is called osteoid
What is the name of the mineralised component of bone matrix that confers hardness?
hydroxyapatite
Apart from bone tissue what else are bones made from?
CT proper (periosteum)
Adipose tissue (fatty marrow)
Blood vessels
Nervous tissue
Articular cartilage
What are the two conformations of bone?
Compact (cortical) bone
Spongy (trabecular) bone
What are the cells in bone tissue and what is their function?
Osteogenic/osteoprogenitor cell
only bone cell capable of cell division. repair and maintain bone tissues
gives rise to osteoblasts
Osteoblast
Synthesises and secretes bone tissue (osteoid)
Gives rise to osteocytes
Osteocyte
Maintains mineralised bone tissue
once osteoblasts that differentiated
Osteoclast
Resorbs bone
Derived from monocyte/macrophage lineage
How are osteocytes formed?
osteoblasts are surrounded by the growing bone matrix. once osteoblasts lay down the matrix that becomes mineralised, they become trapped in a lacunae. They become osteocytes to maintain material they previously laid down
Bone is arranged in layers. What general name is give to these layers?
lamellae
What is the periosteum?
The periosteum is a dense outer layer. It has two layers, an outer fibrous layer and an inner osteogenic layer. In the osteogenic layer there is osteogenic cells that give rise to osteoblasts
What is the name of the functional unit of compact bone that is arranged in a series of concentric lamellae?
osteon
What is in the middle of osteons?
central canals carry blood vessels, nerves and lymphatics
What name is given to the tiny canals through which osteocytes maintain direct contact with their neighbours?
canaliculi
What name is given to the layers of bone that lie between osteons and represent the remnants of old partially resorbed osteons?
interstitial lamellae
What functional feature of compact bone is not evident in spongy/trabecular bone?
osteon
How does spongy bone receive nutrients?
in spaces between which are red and yellow marrow, there are blood vessels and lymphatics present
Trabeculae are lined externally by a cellular layer known as what?
endosteum
What are factors that influence bone remodelling?
Bone remodelling can be influenced by growth, mechanical stress, hormonal and immunological
What is healthy bone tissue?
when bone formation (osteoblastogenesis) is coupled with bone resorption (osteoclastogenesis)
What happens in inflammation of bone tissue?
In inflammation, some diseases can disrupt the balance between bone formation and bone resorption leading to loss of bone and increase osteoclast diagenesis
What happens in periodontitis?
Inflammation causes immune cells to migrate to the tissues. Other inflammatory molecules present in the tissues can cause monocytes to fuse and differentiate into osteoclasts so that the number of osteoclasts will outweigh the number of osteoblasts
As a result bone remodelling has become uncoupled – increased osteoclastogenesis which causes destruction of alveolar bone and tooth loss
What happens in oestoarthritis?
Cartilage is worn down causing movement to become difficult and painful
What is rheumatoid arthritis?
an autoimmune disease where the body attacks it’s own tissues
Rickets is a condition that affects the bone structure of children. Which component of bone is most affected?
hydroxyapatite
What are chondroblasts trapped in?
They become trapped in lacunae forming chondrocytes
What type of cartilage is the epiglottis?
elastic cartilage
What is the difference between articular and hyaline cartilage?
articular covers the articular surfaces of synovial joints, it is a specialised hyaline cartilage that lacks a perichondrium
Where is fibrocartilage found?
in the invertebral discs of the spine and menisci of the knee
Where is hyaline cartilage found?
found on the end of all bones and joints
Where is elastic cartilage found?
external ear and epiglottis, parts of the laryngeal cartilages and in the walls of the Eustachian tubes.
