Cartilage And Bone

Question 0

How does cartilage resist repeated application of pressure?

Answer 0

Extracellular matrix is pliable also has a high amount of hyaluronic acid and so forms hydrated gel.

Question 1

How do chondrocytes obtain their nutrients?

Answer 1

Cartilage is avascular. High ratio of GAGs to collagen permits ready diffusion of nutrients from the blood vessels surrounding the cartilage

Question 2

What are the three types of cartilage?

Answer 2

Hyaline cartilage
Elastic cartilage
Fibrocartilage

Question 3

What does hyaline cartilage contain?

Answer 3

Chondrocytes
Type 2 collagen
Ground substance - proteoglycans and hyaluronic acid
Hyaluronate proteoglycan aggregates are bound to collagen.

Question 4

What does elastic cartilage contain, in addition to that found in hyaline cartilage?

Answer 4

Elastic fibres and elastic lamellae

Question 5

What does fibrocartilage have in addition to hyaline cartilage?

Answer 5

Type 1 collagen

Question 6

What is a group of recently divided chondrocytes called?

Answer 6

Isogenous group

Question 7

What causes chondrocytes in an isogenous group of chondrocytes to separate?

Answer 7

Elaboration of matrix

Question 8

Where is hyaline cartilage found?

Answer 8

Articulating joints.
Rib cage
Nose
Trachea, larynx, and bronchi
Epiphyseal growth plates.

Question 9

What covers the margin of hyaline cartilage?

Answer 9

Perichondrium

Question 10

What cells are present in the perichondrium, and what do they differentiate into?

Answer 10

Fibroblast like cells, which differentiate into chondroblasts and then chondrocytes.

Question 11

Classify perichondrium as a type of connective tissue.

Answer 11

Dense connective tissue (? Irregular)

Question 12

What are the two ways by which cartilage grows?

Answer 12

Appositional growth - matrix secreted by chondroblasts in the perichondrium.
Interstitial growth - matrix secreted by chondrocytes deeper in the cartilage.

Question 13

What is the difference between territorial and interterritorial matrix?

Answer 13

Territorial matrix is more highly sulphated.

Territorial matrix closely surrounds the chondrocytes, recently laid down, interterritorial is further away.

Question 14

What do chondrocytes lie in, and what happens during fixation?

Answer 14

Lacunae, chondrocytes shrink during fixation.

Question 15

What directs the synthetic activity of chondrocytes?

Answer 15

Pressure loads create mechanical, electrical and chemical signals.

Question 16

What makes up the skeleton of the fetus?

Answer 16

Hyaline cartilage.

Question 17

Does the hyaline cartilage on articulating surfaces have a perichondrium?

Answer 17

No.

Question 18

Does elastic cartilage calcify?

Answer 18

No

Question 19

Where is elastic cartilage found?

Answer 19

External ear (pinna), external acoustic meatus, Eustachian tube, epiglottis.

Question 20

How might you identify elastic fibres in a micrograph?

Answer 20

They stain darker.

Question 21

What cells are present in fibrocartilage?

Answer 21

Fibroblasts and chondrocytes.

Question 22

How are the cells often arranged in fibrocartilage?

Answer 22

In rows

Question 23

Where is fibrocartilage found?

Answer 23

Pubic symphysis, articulating discs of the temperomandibular and sternoclavicular joints, intervertebral discs, menisci of the knee.

Question 24

What is the role of fibrocartilage?

Answer 24

Resist shearing forces | Shock absorption

Question 25

Does fibrocartilage have a perichondrium?

Answer 25

No.

Question 26

What lies in the centre of an osteon, and what does it carry?

Answer 26

Haversian canals. Blood vessels, lymphatic vessels and nerves.

Question 27

What canals run perpendicular to the length of the bone, and what do they carry?

Answer 27

Volkmann's canals - blood vessels, lymph vessels and nerves.

Question 28

What are the different possible locations of lamellae in bone?

Answer 28

Inner circumferential lamellae Outer circumferential lamellae Interstitial lamellae Lamellae within an osteon

Question 29

What is the difference between mature and immature bone?

Answer 29

Immature bone has randomly arranged osteocytes. | Mature bone has osteocytes arranged within concentric lamellae of osteons. Resorption canals are parallel with osteons.

Question 30

How are osteons arranged in bone?

Answer 30

Able to branch and terminate.

Question 31

What are canaliculi?

Answer 31

Tunnels in which cytoplasmic extensions of osteocytes lie, that permit transport of substances to osteocytes further away from the Haversian canal. Cytoplasmic extensions are connected by gap junctions.

Question 32

What is the structure of cancellous bone?

Answer 32

Arranged in trabeculae, which have no Haversian or Volkmann's canals, osteocytes lie between concentric lamellae.

Question 33

What lies in the cavities of cancellous bone?

Answer 33

Red bone marrow - haemopoietic cells | Yellow bone marrow - adipose cells

Question 34

How do osteoclasts resort bone?

Answer 34

Release Hydrogen ions and lysosomal enzymes

Question 35

What is a cutting cone?

Answer 35

Bone remodelling unit - osteoclasts followed by osteoblasts laying down osteoid.

Question 36

What is the composition of bone?

Answer 36

65% calcium hydroxyapatite crystals. 23% type 1 collagen 2% non collagen proteins 10% water

Question 37

How does bone resist fractures?

Answer 37

High tensile and compressive strength | Flexibility - lamellae able to slip relative to each other

Question 38

What is the process of fracture healing?

Answer 38

Haematoma forms, granulation tissue forms Procallus forms of fibrocartilage, bony trabeculae form Ossified (endochondral and intermembranous) forms cancellous bone Cancellous bone replaced by cortical bone, then remodelled.

Question 39

How does the fibrocartilaginous callous form?

Answer 39

Capillaries invade haematoma. Tissue rich in fibroblasts and blood vessels (Procallus) forms. Fibroblasts secrete collagen type one which spans the break. Other fibroblasts differentiate into chondroblasts - secrete a sleeve of hyaline cartilage Osteoblasts from periosteum and endosteum form spongy trabecular bone.

Question 40

What occurs during haematoma formation?

Answer 40

Blood vessels in bone are broken, bleeding into fracture, clot = haematoma. Swelling and inflammation. Osteocytes cells at edge of fracture die due to lack of blood supply. Phagocytes and osteoclasts remove dead bone Macrophages eventually remove haematoma.

Question 41

How does bony callus formation in fracture repair occur?

Answer 41

Bony trabeculae form and endochondral ossification converts the fibrocartilaginous callus to cancellous bone. Continues for 2 months

Question 42

How does bone remodelling in fracture repair occur?

Answer 42

Cancellous bone converted to cortical bone. Bulging edges removed by osteoclasts. Eventually takes original shape as responding to same mechanical stressors Occurs for several months.

Question 43

What are the three different bone grafts?

Answer 43

Autograft - from the recipient (most successful) Homograft - from another human - may be rejected. Heterograft - another species - least successful, but calf bones lose antigenicity on refrigeration.