Cartilage And Bone Flashcards
What are the 3 types of cartilage?
Hyaline
Elastic
Fibrocartilage
What does Hyaline Cartilage contain?
Matrix with proteoglycan, hyaluronic acid and type 2 collagen. The hyaluronate proteoglycan aggregates are bound to the collagen matrix fibres . also has chondrocytes.
It’s a dense tissue containing fluid
What demos elastic cartilage contain?
Matrix has proteoglycan and hyaluronic acid, and elastic fibres and elastic lamella (layers). Also has chondrocytes.
It’s tough but flexible.
What does fibrocartilage contain?
Matrix with proteoglycan and hyaluronic acid and type 1 collagen. Also has Chondrocytes
What are the cells types present in hyaline cartilage, how are they arranged and what is there role?
Chondrocytes only. They are present singularly, or in iOS genius groups (small cluster of recently divided cells).
Those within groups seperate as they lay down ECM. Their role is to produce and maintain the ECM. The ECM is cold and firm but also pliable and therefore resisilant to application of pressure.
Where is hyaline cartilage in the fetus and an adult?
In foetal development its the precursor model for bones that develop by endochondrial ossification.
As long bones develop, some cartilage remains at the articulating surface (where bones join), (and some at the epiphyseal plate/growth plate until growth stops).
Found in parts of rib cage, nose, trachea, bronchi and larynx
What is the structure of the ground substance in cartilage?
Hyaluronic acid joins with an attached proteoglycan monomer to form a hyaluronate roteoglycan aggregate.
A very stiff gel -like substance
Where do cohondrocytes lie in the ECM and how do they work?
They lie within lacuna.
There is artefactual shrinkage of cells away from Lacuna walls.
When under pressure, mechanical signals increase synthetic activity to release the pressure in the cartilage.
The chondrocytes lay down ECM within the cells as vesicles. FIbres and GAG/hyularonic acid secreted into space between chondrocytes for tissue expansion.
How does hyaline cartilage grow?
It grows from the periphery towards the centre. This is appositional growth. It grows form the perichondrium (top and bottom of cartilage). This contains elongated, fibroblast like cells that then develop into chondroblasts then chondrocytes.
Why is hyaline cartilage highly hydrated?
As water is non compressible and so it allows resistance to increased loads.
Give 2 example location of Hyaline cartilage and its role in that place.
1) Tracheal wall- forms C-shape cartilage. Reinforces, protects and maintains airway. Lined with pseudostratified epithelium.
2) Articular surfaces (ie knee)-resist pressure
What is the mechanism of arthritis in articular surfaces in simple terms?
An important point of attack in rheumatoid arthritis is the hyaline cartilage. In an adult cells don’t proliferate enough to repair damage. Fibroblasts lay down scar tissue instead. This calcifies with age -loss of flexibility
Where is elastic cartilage found?
3 places in body
- pinna of the ear
- the Eustachian tube (Link inner ear to oral cavity)
- the Epiglottis
How does elastic muscle grow?
It grows form the middle in Interstitial growth
What is the structure of fibrocartilage?
Combo of dense regular connective tissue and hyaline cartilage
Cells distributed in rows
No surrounding perichondrium (has fibroblastic or dense fibroblastic tissue)
Where is fibrocartilage present?
Intervertebral disks
Articular disks of sternoclavicular and temporomandibular joints
Menisci of knee joint
Pubis symphysis
What is the role of fibrocartilage?
Has resilience to act as shock absorber and revisit shearing forces.
How can you tell from histology if a chondrocytes is still laying down matrix?
It still has a nucleus
How does cartilage act as a Bone template/
In feats the long bones are grown by endochondral ossification.
The hyaline cartilage template (is the precursor to most bones) it subsequently mineralises to form bone
How are long bones developed?
1) Initially cartilage provides template
2) Collar of periosteal bone appears in shaft
3) Central cartilage calcifies. Nutrient artery penetrates and supplies osteogenic cells. Primary ossification centre formed
4) Medulla becomes cancellous. Cartilage forms epiphyseal growth plates. They develop secondary centres of ossification.
5) Epiphyseal ossify and growth plates move apart lengthening bone
6) Epiphyseal growth plates replaced by bone. Hyaline Articular cartilage persists
When does the Epiphyseal plate (growth plate) disappear?
When growth ceases
What is the composition and role of inorganic and organic components of bone?
Inorganic = 65% = resist bending and compression (push finger in wont break)
Organic= 35% = revisit pulling and tension forces (pull fingerwont break)
List the organic cells present in bone.
Osteoprogenitor
Osteoblasts
Osteocytes
Osteoclast
What is an osteoprogentior?
What is an osteoprogenitor?
An undifferentiated cell-stem cell )it will produce osteoblasts)
Found in the inner layer of endosteum and periosteum
What are osteoblasts?
Intermediate cells that cannot divide
Found in inner layer of endosteum and spicules
Lays down new bone by secreting organic components of matrix
What is an osteocyte?
Terminally differentiated cell (mature cant differentiate)
Trapped in the osteoblasts
Can no longer lay down matrix-performs tissue maintainance
What is an osteoclast?
Large cell (up to 50 nuclei)
Fused monocytes
On surface of cortical bone
Reabsorb existing bone (using acidic enviro and enzyme when fused on top of cell to create little sealed area)
Look at compact bone slide
R
What is osteoarthritis?
Age related degeneration
Mechanical failure of articulate cartilage
Narrowing of joint space
Bone rubs against bone
What is rheumatoid arthritis?
Autoimmune disease Inflammation of synovial membrane Thickening of joint capsule Damage to underlying bone + articular cartilage Bone + cartilage disintegrate
How does arthritis cause pain?
Degeneration of cartilage
Narrowing of joint space
Growth of bony spurs
Cause inflammation and pain
What changes in arthritic histology?
More osteoclasts - degrade bone
More macrophages-digest bone + alert immune cells
More fluid- inflammation
More hyper plastic synovial lining-put down scar tissue
