Cartilage and Endochondral Ossification

Question 1

What is a chondrocyte and its role?

Answer 1

Role = produce and maintain extracellular matrix

Each lies in a lacuna, loading = activity, deep in cartilage, give rise to isogenous groups = interstitial growth

Question 2

Where is a chondroblast found and what does it do?

Answer 2

in perichondrium (lining), allows growth from periphery = appositional growth

Question 3

Name the lining around cartilage

Answer 3

Perichondrium lines cartilage, not on articulated surfaces, contains fibroblasts-like cells, can diff into chondrocytes

Question 4

What is the structure of hyaline cartilage?

Answer 4

proteoglycans + hyaluronic acid bound to fine collagen matrix + collagen II fibres, lined by perichondrium

Question 5

Which cartilage type does not calcify?

Answer 5

elastic

Question 6

Which cartilage gives shape and support?

Answer 6

elastic

Question 7

Where is fibrous cartilage found?

Answer 7

disks, pubic synthesis (areas of high pressure), present at enthuses (point of attachment of tendon + bone)

Question 8

Where is elastic cartilage found?

Answer 8

pinna (inner ear), epiglottis

Question 9

How does hyaline cartilage relate to foetal bone development?

Answer 9

In the foetal skeleton hyaline cartilage is the precursor model of those bones which develop by endochondral ossification.

Question 10

In which cartilage will you find flat fibroblasts?

Answer 10

fibrous

Question 11

What is the function of hyaline cartilage?

Answer 11

Reduces friction, absorb shock

Question 12

What type of tissue is cartilage?

Answer 12

Connective

Question 13

The cartilage matrix has a large ratio of what?

Answer 13

Large ratio of glycosaminoglycan’s (GAGs) to type II collagen = diffusion of substances between chondrocytes + blood vessels. GAGs = high density –ve charges = attract water = hydrated gel

Question 14

What does ossification mean?

Answer 14

formation of bone

Question 15

What is the structure of elastic cartilage?

Answer 15

matrix like hyaline, addition of elastic fibres + elastic lamellae = elasticity, lined by perichondrium

Question 16

What is the structure of fibrous cartilage?

Answer 16

matrix like hyaline, abundant collagen I fibres = combination of dense regular connective tissue + hyaline cartilage, NO PERICHONDRIUM

Question 17

What does the word metaphysis mean?

Answer 17

columns of calcified cartilage extend from the growth plate and become mineralised

Question 18

What is the difference between epiphysis and diaphysis?

Answer 18

Epiphysis –> end part of a long bone, initially growing separately from the shaft, Diaphysis –> shaft or central part of a long bone

Question 19

Describe a synovial joint

Answer 19

movable joint, juxtaposed bone ends are covered by hyaline or fibrous, lie within synovial fluid bound by articular capsule lined by synovial membrane (macrophages removes debris from space, fibroblast-like cells = secrete synovial fluid)

Question 20

Describe endochondral ossification

Answer 20

1. Collar of periosteal bone appears in shaft,
2. Nutrient arteries penetrate, supplying bone-depositing osteogenic cells – primary ossification centre formed,
3. Medulla becomes cancellous bone, cartilage forms epiphyseal growth plates. Epiphyses develop secondary centres of ossification
4. Epiphyses ossify, growth plates move apart lengthening bone,
5. Epiphyseal growth plates replaced by bone. Hyaline articular cartilage persists

Question 21

In what space does it chondrocytes lie?

Answer 21

Lacuna

Question 22

What type of tissue is perichondrium?

Answer 22

Dense connective tissue

Question 23

What is cartilage growth from the periphery know as?

Answer 23

Appositional growth

Question 24

What is perichondrium?

Answer 24

Dense connective tissue that envelops hyaline and elastic cartilage where it is not at a joint

Question 25

What is a GAG?`

Answer 25

Glycosaminoglycan - connected to proteoglycan - connected to hyaluronic acid. High density of -ve charge on GAGs = attracts water = forms hydrating gel in the cartilage matrix = allows withstanding of pressure

Question 26

What is hyaluronic acid?

Answer 26

Makes up the gel in the extracellular matrix - assists resilience of repeated application of pressure

Question 27

What does a large ratio of GAGs to type II collagen in cartilage permit?

Answer 27

Ready diffusion between chondrocytes and blood vessels surrounding cartilage

Question 28

Does cartilage have blood vessels?

Answer 28

No

Question 29

What fibres don’t calcify?

Answer 29

Elastic

Question 30

What is deposition of further matrix by isogenous groups deep in the matrix called?

Answer 30

Interstitial growth

Question 31

Outline: structure, function, placement and cell type for hyaline cartilage

Answer 31

STRUCTURE: GAGs - proteoglycans - hyaluronic acid, collagen II. FUNCTION: reduce friction, absorb shock. PLACEMENT: trachea, bronchi, articulating ends of bones. CELL TYPE: chondrocytes

Question 32

Outline: structure, function, placement and cell type for elastic cartilage

Answer 32

STRUCTURE: like hyaline + elastic fibres. FUNCTION: shape and support. PLACEMENT: pinna (ear), epiglottis. CELL TYPE: chondrocytes

Question 33

Outline: structure, function, placement and cell type for fibrous cartilage

Answer 33

STRUCTURE: like hyaline + collagen I. FUNCTION: withstand high pressure. PLACEMENT: disks, meniscus of knee joint, pubic symphysis. CELL TYPE: fibroblasts

Question 34

What are the 2 types of cartilage growth and how are they different?

Answer 34

Appositional growth = THICKENING = growth from outside by chondroblasts from the perichondrium.

Interstitial growth = LENGTHENING = growth from the inside by chondrocytes that have differentiated into isogenous groups