ToB - Cartilage Flashcards
What is the importance of GAGs in cartilage?
They are negatively charged so attract water to form a hydrated gel matrix. The transient movement of water in the matrix is what permits resilience to varying degrees of pressure.
What is found in the matrix of hyaline cartilage?
Proteoglycans with GAGs attached
Hyaluronic acid
Type II collagen to which hyaluronate proteoglycan aggregates bind
Chondrocytes which synthesise and maintain matrix
Chondroblasts in perichondrium
How does pressure affect chondrocytes?
Pressure loads create electrical, chemical and mechanical signals which direct the synthetic activity of the chondrocytes.
How are chondrocytes found in hyaline cartilage?
They lay in lacunae
May be single or may have divided mitotically to form isofenous groups.
Where is hyaline cartilage found?
At the surface of articulating bones
Foetal skeleton
Costal cartilage
Trachea/larynx
Which cartilage types contain perichondrium?
Elastic and hyaline (except on edges of articulating bones)
What is the perichondrium made of?
Dense CT so contains: Fibroblast like cells that can differentiate into chondroblasts Collagen Nerves Blood vessels
It has an outer fibrous layer of the CT and an inner chondrogenic layer which contains the fibroblast like cells.
What is appositional growth?
Cartilage can grow from the periphery as the perichondrium contains fibroblast like cells that can differentiate into chondroblasts to produce cartilage.
What is interstitial growth?
Deposition of further cartilage matrix by the isogenous groups of chondrocytes.
What is found in elastic cartilage?
Proteoglycans with GAGs attached
Hyaluronic acid
Type II collagen to which hyaluronate proteoglycan aggregates bind
Chondrocytes which synthesise and maintain matrix
Chondroblasts in perichondrium
Elastic fibres to confer elasticity
Where is elastic cartilage found?
Pinna of the ear
Eustachian tube
Epiglottis
How does elastic cartilage appear different to other cartilage forms n micrographs?
It has darker stained fibrillar material around the lacunae
What are the two types of matrix in hyaline cartilage and how/why do they appear different in micrographs?
Territorial - darker due to more highly sulphated
Interterritorial - lighter
How does cartilage obtain nutrients?
It is a vascular so obtains nutrients via diffusion. This diffusion between chondrocytes and blood vessels is permitted by a large ratio of GAGs to type II collagen.
When may fibrocartilage undergo calcification?
To perform fracture repair (formation of fibrocartilaginous callus)
