Flashcards in BL - Cartilage And Endochondral Ossification Deck (35):
What is the name given to an avascular tissue which consists of an extensive extracellular matrix in which lie chondrocytes?
What is the function of chondrocytes in cartilage?
They produce and maintain the extracellular matrix. Chondrocytes are the only cells found in healthy cartilage.
What is the benefit of having a large ratio of GAGs to type 2 collagen in the cartilage matrix?
It permits ready diffusion of substances between the chondrocytes and the blood vessels surrounding the cartilage.
The large amount of hyaluronic acid in the extracellular matrix allows it to be resilient to what?
Repeated application of pressure. The matrix is solid and firm but still pliable.
How do GAGs attract water? (hint - it's to do with the charge)
The high density of negative charges attract water, forming a hydrated gel.
What are the three types of cartilage?
Hyaline, elastic, fibrocartilage.
How is hyaline cartilage structured?
Matrix containing proteoglycans, hyaluronic acid and type II collagen.
How is elastic cartilage structured?
Matrix like hyaline cartilage but with elastic fibres and elastic lamellae.
How is fibrocartilage structured?
Abundant type I collagen in addition to hyaline matrix structure.
What is an "isogenous group" in cartilage?
A small cluster of recently divided chondrocytes.
How many different types of cell are present in hyaline cartilage?
Just one (chondrocytes).
Where is hyaline cartilage situated?
At "articulating surfaces" (where bones rub together lots), in parts of rib cage, trachea, bronchi and larynx.
What is the role of hyaline cartilage in the developing foetus?
It is the pre-cursor of bones which develop via echondral ossification.
What is the perichrondrium?
A layer of dense connective tissue which covers the margin of hyaline cartilage. It contains many cells which can develop into chondrocytes. (It's basically like having loads of spare tyres).
Cartilage grows in from the perichrondrium towards the chondrocytes. What is this called?
How is the activity of the chondrocytes directed?
Pressure loads applied to the cartilage create mechanical, electrical and chemical signals that direct the synthetic activity of the chondrocytes.
Is the perichondrium present at articulating surfaces?
What is the name given to the end of a bone?
What is a lacuna?
A small space containing an osteocyte in bone, or a chondrocytes in cartilage.
Does elastic cartilage calcify with aging?
Nah. Hyaline does though.
Where is elastic cartilage found?
The external ear (pinna), acoustic meatus, epiglottis and eustachian tube.
Why does elastic cartilage often appear dark on images?
An abundance of elastin fibres.
What is fibrocartilage? Which cells does it contain?
It is a combination of dense regular connective tissue and hyaline cartilage. It contains chondrocytes and fibroblasts.
Where is fibrocartilage found?
Intervertebral discs, menisci of knee, pubic symphysis, articulate discs of sternoclavicular (chest) and temporomandibular (side of head) joints.
What is an enthesis?
A point of attachment of tendon and bone. Fibrocartilage may be present here.
What is endochondral ossification?
The REPLACEMENT of a pre-existing HYALINE CARTILAGE TEMPLATE with BONE, which is the way that most of the bones of the body develop.
What is an epiphyseal growth plate?
A hyaline cartilage plate found at the end of each long bone. It is where growth initiates from, and disappears once adulthood is reached.
At which stage of development does a "collar" of periosteal bone begin to appear in the shaft of the developing bone?
6-8 weeks (embryo)
At which stage of development does the central cartilage calcify, the nutrient artery penetrate and the primary ossification centre form?
8-12 weeks (foetus)
During postnatal development, the medulla becomes cancellous bone and the cartilage forms _____ plates. Epiphyses develop secondary _______ .
1) epiphyseal growth plates
2) centres of ossification
At what stage of human development do the epiphyses ossify?
When are the epiphyses growth plates replaced by bone?
When maturity is reached.
What's the difference between an osteoblast and an osteoclast?
Osteoblasts make bone, osteoclasts degrade it.
What is a synovial joint?
A moveable joint where the bone ends are covered by hyaline cartilage/fibrocartilage and lie within lubricating synovial fluid bounded by a joint cavity.