Cartilage And Bone

Question 1

What are the 3 types of cartilage?

Answer 1

Hyaline
Elastic
Fibrocartilage

Question 2

What does Hyaline Cartilage contain?

Answer 2

Matrix with proteoglycan, hyaluronic acid and type 2 collagen. The hyaluronate proteoglycan aggregates are bound to the collagen matrix fibres . also has chondrocytes.

It’s a dense tissue containing fluid

Question 3

What demos elastic cartilage contain?

Answer 3

Matrix has proteoglycan and hyaluronic acid, and elastic fibres and elastic lamella (layers). Also has chondrocytes.

It’s tough but flexible.

Question 4

What does fibrocartilage contain?

Answer 4

Matrix with proteoglycan and hyaluronic acid and type 1 collagen. Also has Chondrocytes

Question 5

What are the cells types present in hyaline cartilage, how are they arranged and what is there role?

Answer 5

Chondrocytes only. They are present singularly, or in iOS genius groups (small cluster of recently divided cells).
Those within groups seperate as they lay down ECM. Their role is to produce and maintain the ECM. The ECM is cold and firm but also pliable and therefore resisilant to application of pressure.

Question 6

Where is hyaline cartilage in the fetus and an adult?

Answer 6

In foetal development its the precursor model for bones that develop by endochondrial ossification.

As long bones develop, some cartilage remains at the articulating surface (where bones join), (and some at the epiphyseal plate/growth plate until growth stops).

Found in parts of rib cage, nose, trachea, bronchi and larynx

Question 7

What is the structure of the ground substance in cartilage?

Answer 7

Hyaluronic acid joins with an attached proteoglycan monomer to form a hyaluronate roteoglycan aggregate.

A very stiff gel -like substance

Question 8

Where do cohondrocytes lie in the ECM and how do they work?

Answer 8

They lie within lacuna.
There is artefactual shrinkage of cells away from Lacuna walls.
When under pressure, mechanical signals increase synthetic activity to release the pressure in the cartilage.
The chondrocytes lay down ECM within the cells as vesicles. FIbres and GAG/hyularonic acid secreted into space between chondrocytes for tissue expansion.

Question 9

How does hyaline cartilage grow?

Answer 9

It grows from the periphery towards the centre. This is appositional growth. It grows form the perichondrium (top and bottom of cartilage). This contains elongated, fibroblast like cells that then develop into chondroblasts then chondrocytes.

Question 10

Why is hyaline cartilage highly hydrated?

Answer 10

As water is non compressible and so it allows resistance to increased loads.

Question 11

Give 2 example location of Hyaline cartilage and its role in that place.

Answer 11

1) Tracheal wall- forms C-shape cartilage. Reinforces, protects and maintains airway. Lined with pseudostratified epithelium.
2) Articular surfaces (ie knee)-resist pressure

Question 12

What is the mechanism of arthritis in articular surfaces in simple terms?

Answer 12

An important point of attack in rheumatoid arthritis is the hyaline cartilage. In an adult cells don’t proliferate enough to repair damage. Fibroblasts lay down scar tissue instead. This calcifies with age -loss of flexibility

Question 13

Where is elastic cartilage found?

Answer 13

3 places in body

• pinna of the ear
• the Eustachian tube (Link inner ear to oral cavity)
• the Epiglottis

Question 14

How does elastic muscle grow?

Answer 14

It grows form the middle in Interstitial growth

Question 15

What is the structure of fibrocartilage?

Answer 15

Combo of dense regular connective tissue and hyaline cartilage
Cells distributed in rows
No surrounding perichondrium (has fibroblastic or dense fibroblastic tissue)

Question 16

Where is fibrocartilage present?

Answer 16

Intervertebral disks

Articular disks of sternoclavicular and temporomandibular joints

Menisci of knee joint

Pubis symphysis

Question 17

What is the role of fibrocartilage?

Answer 17

Has resilience to act as shock absorber and revisit shearing forces.

Question 18

How can you tell from histology if a chondrocytes is still laying down matrix?

Answer 18

It still has a nucleus

Question 19

How does cartilage act as a Bone template/

Answer 19

In feats the long bones are grown by endochondral ossification.

The hyaline cartilage template (is the precursor to most bones) it subsequently mineralises to form bone

Question 20

How are long bones developed?

Answer 20

1) Initially cartilage provides template
2) Collar of periosteal bone appears in shaft
3) Central cartilage calcifies. Nutrient artery penetrates and supplies osteogenic cells. Primary ossification centre formed
4) Medulla becomes cancellous. Cartilage forms epiphyseal growth plates. They develop secondary centres of ossification.
5) Epiphyseal ossify and growth plates move apart lengthening bone
6) Epiphyseal growth plates replaced by bone. Hyaline Articular cartilage persists

Question 21

When does the Epiphyseal plate (growth plate) disappear?

Answer 21

When growth ceases

Question 22

What is the composition and role of inorganic and organic components of bone?

Answer 22

Inorganic = 65% = resist bending and compression (push finger in wont break)

Organic= 35% = revisit pulling and tension forces (pull fingerwont break)

Question 23

List the organic cells present in bone.

Answer 23

Osteoprogenitor

Osteoblasts

Osteocytes

Osteoclast

Question 24

What is an osteoprogentior?

What is an osteoprogenitor?

Answer 24

An undifferentiated cell-stem cell )it will produce osteoblasts)

Found in the inner layer of endosteum and periosteum

Question 25

What are osteoblasts?

Answer 25

Intermediate cells that cannot divide
Found in inner layer of endosteum and spicules
Lays down new bone by secreting organic components of matrix

Question 26

What is an osteocyte?

Answer 26

Terminally differentiated cell (mature cant differentiate)
Trapped in the osteoblasts
Can no longer lay down matrix-performs tissue maintainance

Question 27

What is an osteoclast?

Answer 27

Large cell (up to 50 nuclei)
Fused monocytes
On surface of cortical bone
Reabsorb existing bone (using acidic enviro and enzyme when fused on top of cell to create little sealed area)

Question 28

Look at compact bone slide

Answer 28

R

Question 29

What is osteoarthritis?

Answer 29

Age related degeneration
Mechanical failure of articulate cartilage
Narrowing of joint space
Bone rubs against bone

Question 30

What is rheumatoid arthritis?

Answer 30

Autoimmune disease 
Inflammation of synovial membrane 
Thickening of joint capsule 
Damage to underlying bone + articular cartilage 
Bone + cartilage disintegrate

Question 31

How does arthritis cause pain?

Answer 31

Degeneration of cartilage
Narrowing of joint space
Growth of bony spurs
Cause inflammation and pain

Question 32

What changes in arthritic histology?

Answer 32

More osteoclasts - degrade bone
More macrophages-digest bone + alert immune cells
More fluid- inflammation
More hyper plastic synovial lining-put down scar tissue