Session 12 Body Logistics CARTILAGE Flashcards
(38 cards)
NAME THE SPECIALISED CELLS OF CARTILAGE AND STATE THEIR FUNCTION
- CHONDROCYTES
- THEY PRODUCE AND MAINTAIN THE EXTRACELLULAR MATRIX IN WHICH THEY LIE.
BRIEFLY DESCRIBE CARTILAGE:
CARTILAGE IS AN EXAMPLE OF SPECIALISED CONNECTIVE TISSUE
- It is AVASCULAR
- Consists of an extensive extracellular matrix in which the chondrocytes lie
- Chondrocytes - produce and MAINTAIN the extracellular matrix
DESCRIBE THE COMPOSITION OF CARTILAGE
- Higher ratio of GAG to Type 2 collagen ( allows ready diffusion of sub between chondrocytes and blood vessels)
- A lot of hyaluronic acid in ECM
- High density of negatively charged GAG’s ( attract water)= hydrated gel
- Hyaluronic acid with its many proteoglycan monomers interwoven in network of type 2 collagen fibrils.
What are the three types of cartilage?
H- Hyaline
E- Elastic
F- Fibrocartilage
DESCRIBE THE STRUCTURE OF HYALINE CARTILAGE
- only cell =Chondrocytes :- Singly or cluster isogenous groups (newly divided) ( each chondrocytes sits in a lacuna)
Matrix- Hyaluronic acid, proteoglycan (hydration of the matrix), TYPE 2 collagen fibres - Perichondrium covers the margin of hyaline cartilage (but not at articulating surfaces and at the epiphyseal plate)
Where is Hyaline Cartilage found?
- ARTICULATING SURFACES- ARTICULATING CARTILAGE AT JOINTS( no perichondrium)
- EPIPHYSEAL PLATE ( no perichondrium)
- CARTILAGE IN THE NOSE
- COSTAL CARTILAGE
- RIBS AND STERNUM
- RESPIRATORY- TRACHEA AND LARYNX AND Lungs ( disappears in the smaller respiratory tubes
What is the link between endochondral ossification and hyaline cartilage?
- Hyaline cartilage= template for most bones
- Becomes mineralised to form bones
- In a 14 week foetus - have a lot of cartilage left especially at the epiphyses
What are the two types of ossification?
- ENDOCHONRAL OSSIFICATION- Hyaline cartilage acts as model for the development of bone ( long bones- limbs)
- INTRAMEMBRANOUS OSSIFICATION - Direct formation from mesenchymal cells no cartilage involved ( flat bones - those of the skull, scapula)
What is the perichondrium?
-Covers the margin of cartilage
- (edge of cartilage)
= DENSE CONNECTIVE tissue
Contains elongate fibroblast like cells which develop—> FLAT chondroblasts (secrete ECM components)—> (Round) Chondrocytes
Fibroblast like cell—> Chondroblast—> Chondrocytes ( apposition always growth)
What are Two types of growth in the cartilage?
- Appositional growth ( growth from the periphery fibroblast—> chondroblast—> chondrocytes)
- Interstitial growth- mitotic division of chondrocytes ( form isogenous groups- that separate as they secrete ECM)
Explain the calcification of cartilage
- Hyaline cartilage calicifies with age
- Elastic cartilage does not
E.g. the c shaped cartilage in the trachea= hyaline cartilage can be calcified in elderly people
DESCRIBE THE COMPOSITION OF ELASTIC CARTILAGE:
- Proteoglycans
- Hyaluronic acid
- Type 2 collagen fibres ( same composition as HC but have *)
- *Elastic fibres
- Elastic lamellae
WHERE IS ELASTIC CARTILAGE FOUND ? (4 LOCATIONS)
- Pinna ( external ear)
- External auditory meats
- Eustachian Tube
- Epiglottis
How is elastic cartilage different from hyaline cartilage in terms of histology?
- Elastic fibres present in the ECM - have dark staining in hyaline cartilage you would not see this
DESCRIBE THE COMPOSITION OF FIBROCARTILAGE
- Abundant type 1 cartilage (gives its strength to resist shearing forces)
- Hyaluronic acid, Proteoglycans, Type two collagen
- Two cell types- chondrocytes - arranged in rows or as isogenous groups and fibroblast
FIBROCARTILAGE IS A COMPOSITION OF
- DCT and hyaline cartilage
WHERE IS FIBROCARTILAGE LOCATED IN THE BODY?
- Pubic symphysis
- Sternoclavicular joint
- Tempromandibular joint
- Intervertebral discs
- Menisci of the knee ( as c shaped along with the hyaline cartilage)
What do footballers tend to damage and what is significant about this?
Meniscus of the knee ( menisci of the knee joint)-
CARTILAGE is said to be irreparable because it is avascular therefore need to have surgical intervention.
( However, some research drilling lots of tiny holes into cartilage stimulates it to repair)
WHAT IS ENDOCHONDRAL OSSIFICATION?
- Replacement of existing hyaline cartilage ( model for bone development)by bone
- the way most bones of our body are produced
- Flat bones eg. Ribs and Limbs
What DO we see in 14 Week foetus in regards to endochondral ossification?
Most of the bones are replaced by bone (the diaphyses)
However at the epiphysis you can still se cartilage present eg. In the metacarpals of the hand
What is the epiphyseal plate?
- Growth plate made up of hyaline cartilage
- Still present in an individual is growing
- Will disappear after the CESSATION of growth
DESCRIBE THE PROCESS OF LONG BONE FORMATION BY ENDOCHONDRAL OSSIFICATION
- Initial cartilage (5-6 wk embryo)
- Formation fo the collar of periosteal bone in the diaphyses (6-8 wk embryo- newly formed osteoblasts gather at diaphyses wall form the bone collar.
- Central cartilage calcifies, nutrient artery penetrates, supplying bone depositing osteogenic cells- PRIMARY OSSIFICATION CENTRE FORM (Fetus 8-12 wks)
- Medulla = to spongy bone , CARTILAGE FORMS at the epiphyseal plate - secondary ossification sites develop at epiphyses - POST NATAL
- EPIPHYSES OSSIFY AND growth plates continue to move part at which lengthens the bone.- PREPUBERTAL
- Epiphyseal growth plates(Ossify-cessation of growth) are replaced by bone. Hyaline articular cartilage persists. MATURE ADULT
BONE INCREASES IN LENGTH VIA
ENDOCHONDRAL OSSIFICATION
INCREASE IN GIRTH OF THE BONE ( BONE IS WIDER) IS VIA
Periosteal ossification which increases girth of the bone is INTRAMEMBRANOUS OSSIFICATION
