cartilage, ossification and bone disease (rest look at Callum's ESA1)

Question 1

What facilitates the ready diffusion of substances between the chondrocytes and the blood vessels surrounding the avascular cartilage?

Answer 1

Large ratio of GAGs (glycoaminoglycans) to type II collagen

Question 2

What component of the extracellular matrix assists cartilage’s resilience to repeated application of pressure?

Answer 2

Large amounts of hyaluronic acid

Question 3

What is the extracellular matrix of hyaline cartilage composed of?

Answer 3

proteoglycans, hyaluronic acid and type II collagen

Question 4

Elastic cartilage has an extracellular matrix like that of hyaline cartilage but with the addition of which molecules?

Answer 4

Many elastic fibres and elastic lamellae

Question 5

Fibrocartilage has an extracellular matrix like that of hyaline cartilage but with the addition of which molecules?

Answer 5

Abundant type I collagen fibres

Question 6

What is the only cell type present in hyaline cartilage?

Answer 6

Chrondrocytes

Question 7

What are isogenous groups of chondrocytes?

Answer 7

Chrondrocytes groups that have clearly originated from a recent mitotic division

Question 8

How is hyaline cartilage so resilient to varying pressure loads?

Answer 8

The cartilage extracellular matrix is highly hydrated and transient moventent of water within the matrix can occur

Question 9

What is the ‘territorial matrix’ and ‘interterritorial matrix’ of cartilage?

Answer 9

The matrix surrounding a chondrocyte or isogenous group which stains darker (with H&E). ‘Interritorial matrix’ is matrix between groups/single chondrocytes that stains lighter

Question 10

What is the shrinkage artefact that is seen in histiological slides of cartilage?

Answer 10

Lacunae - artifical space around chondrocytes

Question 11

The hyaline cartilage that forms the epithyseal growth plates and articulating surfaces of bones, is lacking what compared to the hyaline cartilage elsewhere?

Answer 11

Perichondrium

Question 12

Where is elastic cartilage found?

Answer 12

External ear (pinna)
External acoustic meatus (ear canal)
Epiglottis
Eustachian tube (tube between middle ear and nasopharynx)

Question 13

Fibrocartilage is different from elastic cartilage and hyaline cartilage, in that it has two not one type of cell present. Name the cells

Answer 13

Chrondrocytes

Fibroblasts

Question 14

Fibrocartilage is like a combination of which connective tissues?

Answer 14

Dense regular connective tissue

Hyaline cartilage

Question 15

What are some important histiological features of fibrocartilage?

Answer 15

Cells are often seen distributed in rows or isogenous groups
NO surrounding perichondrium
Chondrocytes not as abundant as in other types of cartilage

Question 16

Where is fibrocartilage found?

Answer 16

Intervertebral discs
Articular disks of sternoclavicular and temporomandibular joints
Menisci of the knee joint
Pubic symphysis
At some entheses (tendon and bone attachments)

Question 17

Next to the endosteum and periosteum what structures can be seen in cortical/compact bone that run paralell to the long axis of the bone?

Answer 17

Endosteum - Inner circumferential lamellae

Periosteum - Outer circumferential lamellae

Question 18

What do Haversian canals and Volkmann’s canals carry?

Answer 18

Blood vessels, lymph vessels and nerves

Question 19

How can you differentiate between a Haverisian and Volkmann canal?

Answer 19

Haversian have concentric lamellae surrounding them, Volkmann canals don’t

Question 20

How are osteocytes arranged in immature bone vs mature bone?

Answer 20

Fairly random vs in concentric lamellae of osteons

Question 21

In mature bone which direction do the reabsorption canals run?

Answer 21

Parallel with the osteon’s long axis

Question 22

What is notable about the appearence of osteons as they travel longitudinally (in the same plane as the bone)?

Answer 22

They can branch into multiple osteons

Question 23

How can bone be sectioned?

Answer 23

1. Decalcified - otherwise blunts blade

2. Ground down

Question 24

Where are osteocytes found in an osteon?

Answer 24

Entombed in lacunae between lamellae

Question 25

How do osteocytes receive nutrients and get rid of waste?

Answer 25

They have slender cytoplasmic processes which reach out to adjacent osteocyte via canaliculi. These processes connect via gap junctions such that nutrients can be passed between them. Canaliculi are believed to connect with the central Haversian canal

Question 26

What is the difference in histiological structure between cancellous and cortical bone?

Answer 26

Cancellous is similar to cortical (has osteocytes lying between lamellae) but has no Haversian or Volkmann’s canals.

Question 27

What is the structure of cancellous trabeculae?

Answer 27

Each trabeculum - numerous osteocytes embedded within irregular lamellae
Osteoblast and osteoclasts on their surface act to remodel them

Question 28

What lies between the trabeculae of cancellous (spongy) bone?

Answer 28

Adipose and haemopoietic cells

Question 29

Which mineral makes up 65% of bone?

Answer 29

calcium hydroxyapatite crystals

Question 30

Which type of collagen makes up 23% of bone?

Answer 30

Type 1

Question 31

What is thought to confer some of the flexibility of bone?

Answer 31

Lamellae are thought to be able to slip, relative to each other, before excessive load causes fracture