ToB 11 Cartilage and Bone Flashcards
Name the 3 types of cartilage:
1) Hyaline cartilage
2) Fibrous cartilage
3) Elastic cartilage
What is the function of chondrocytes?
Chondrocytes produce and maintain the extracellular matrix within cartilage
How can you tell the upper edge of cartilage from the middle, in a histology slide?
The upper edge has flattened cells, which are the developing chondrocytes, and the middle of the cartilage will be full of extracellular matrix
Describe the properties of extracellular matrix within cartilage:
Solid, firm, pliable
Large amounts of WHAT in the ECM of cartilage gives it resilience to the repeated application of pressure?
Hyaluronic acid
How do the proteoglycans and hyaluronic acid molecules allows the cartilage ground substance to form a hydrated gel?
The high density of negative charges on the GAGs in cartilage ground substance attracts water molecules strongly, forming the hydrated gel.
What molecules in cartilage ground substance form the hydrated gel consistency?
Proteoglycans, hyaluronic acid molecules and water
What is hyaline cartilage extracellular matrix composed of?
- Proteoglycans
- Hyaluronic acid molecules
- Type II collagen
What type of cells are present in hyaline cartilage?
Chondrocytes
What is elastic cartilage extracellular matrix composed of?
- Proteoglycans
- Hyaluronic acid molecules
- Type II collagen
- Elastic fibres (form lamellae)
What is different between the composition of hyaline cartilage extracellular matrix compared with elastic?
Elastic cartilage is the same as hyaline, but with the addition of elastic fibers.
What is fibrocartilage extracellular matrix composed of?
- Proteoglycans
- Hyaluronic acid molecules
- Type I collagen
- Type II collagen
What are the main differences in the composition between hyaline and fibrocartilage?
- Fibrocartilage contains abundant type I collagen, which is not a component of hyaline cartilage
- Fibrocartilage contains less cells compared to hyaline cartilage
Why do chondrocytes sometimes form isogenous groups?
Chondrocytes form these clusters if they have recently divided, but will separate.
What is the name of the process by which fetal hyaline cartilage develops into bone?
Endochondral ossification
What type of cartilage is the precursor for the human skeleton (ie present in foetus)?
Hyaline cartilage
Where is hyaline cartilage present while long bones are developing?
- Articulating surfaces
- Epiphyseal plates
Where is hyaline cartilage sited?
- Articulating surfaces of joints
- Costal cartilage (extend ribcage)
- Nose
- Larynx, trachea, bronchi
What is the name of the dense layer of cells which cover the margin of hyaline cartilage?
Perichondrium
How can you tell the perichondrium from the main hyaline cartilage in a histology slide?
The perichondrium is at the edge of the cartilage, and contains many elongated cells, compared to the main hyaline cartilage which contain large cells surrounded by ECM.
What type of cells produce and maintain cartilage extracellular matrix?
Chondrocytes
What type of cells are contained in the perichondrium?
Fibroblast-like cells
Describe the formation of chondrocytes:
Fibroblast-like cells from the perichondrium develop into chondroblasts, which then develop into chondrocytes.
What is meant by ‘appositional growth’?
Growth by the addition of new layers on those previously formed - growth from the periphery.
What types of growth does cartilage undergo?
Appositional and interstitial growth
What is meant by ‘interstitial growth’?
Growth within layers that have already been formed.
How does cartilage grow via interstitial growth?
Chondrocytes deep in the cartilage may divide, increasing the number of cells present, so ECM is increased.
What factors give hyaline cartilage resilience against varying pressure loads?
- Highly hydrated extracellular matrix
- Transient movement of water
What name describes the ECM close to chondrocytes, which stains dark with H&E?
Territorial matrix
What two types of matrix can be differentiated when the hyaline cartilage is stained with H&E? Why can they be differentiated?
1) Territorial matrix
2) Interterritorial matrix
The territorial matrix stains darker than the interterritorial matrix, as it is more highly sulphated
What are the white lacunae that the chondrocytes lie within, which can be viewed on histology slides?
These are artefactual shrinkages due to slide preparation.
How do pressure loads direct the synthetic activity of chondrocytes?
Pressure loads create mechanical, electrical and chemical signals, to which the chondrocytes respond to.
At which cartilage surfaces is a perichondrium present?
Non-articulating surfaces
What are the 2 types of bone present in the body?
1) Cortical
2) Cancellous
What is cancellous bone?
It is very porous and contains red bone marrow, where blood cells are made. It is weaker and easier to fracture than cortical bone.
What is cortical bone?
Very dense and strong bone, which is difficult to fracture. Its primary purpose is providing structural support to the body and its organs and tissues.
Long bones can be split into 5 sections, what are they?
1) Proximal epiphysis
2) Metaphysis
3) Diaphysis
4) Metaphysis
5) Distal epiphysis
What is the name of the shaft-part of a long bone?
Diaphysis
Why is it important that an articulating surface of bone is very smooth?
To allow a friction-free environment, for articulation with the adjacent bone