Flashcards in Cartilage and Bone Deck (72):
0
Is cartilage vascular or avascular
-Avascular
1
In general, what two components make up cartilage?
-Chondrocytes
-Extensive ECM
2
What is the function of the chondrocytes within cartilage?
-To produce and maintain ECM
3
What is the ECM of cartilage made up of?
-Hyaluronic acid and proteoglycan aggregates
-Proteoglycan monomers have a core protein with gags attached
-Collagen fibres
4
What are the characteristic features of cartilage?
-Resilience to repeated applied pressure
-Non-compressibility
-Solid but pliable
-Elasticity
5
What does the gag:collagen ratio of the ECM ensure?
-The ratio permits diffusion of nutrients to the chondrocytes from the surrounding blood vessels
6
Which type of collagen is predominantly found in cartilage?
-Type 2
7
What type of tissue is cartilage?
-Connective tissue
8
Name the three type os cartilage
-Hyaline
-Elastic
-Fibrocartilage
9
What is the ECM of hyaline cartilage made of?
-Hyaluronic acid and proteoglycan aggregates bound to type II collagen
-Proteoglycan monomers have a core protein with gags attached
10
What is the main characteristic feature of hyaline cartilage?
-Resilience to repeated pressure loads
11
What occurs when pressure loads are applied to hyaline cartilage?
-Creates mechanical, electrical and chemical signals which direct the synthetic activity of the chondrocytes
12
What cell type is found in hyaline cartilage?
-Chondrocytes
13
Where in the body is hyaline cartilage found?
-larynx, trachea, bronchus
-ear and nose
-ribs
-articulating surfaces of joints
-At the epiphyseal growth plate
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What surrounds cartilage?
-Perichondrium
15
What is particular about the hyaline cartilage at articulating surfaces of joints?
-No perichondrium as would be damaged, needs to be smooth and thus cannot repair itself, gets nutrients from surrounding fluid
-Also contains type III collagen
16
Why does hyaline cartilage at articulating surfaces have irregular boundaries?
-To prevent shearing off
17
Describe how chondrocytes are distributed in hyaline cartilage
-Lie in lacunae, separated by ECM that they secrete or in isogenous groups if just recently divided, which eventually become to lie separately
18
Why does hyaline cartilage remain at the epiphyseal growth plates?
-To allow elongation of long bones
19
What is interstitial growth in cartilage?
-Growth which occurs as a result of isogenous groups secreting matrix and becoming single cells laying in separate lacuna
20
What is appositional growth?
-Growth from the periphery
-The perichondrium contains elongate fibroblast-like cells which develop into chondroblasts and then into chondrocytes, laying down ground substance as they develop
21
What is the territorial matrix?
-The highly sulphated deeply staining matrix immediately surrounding chondrocytes
22
What is the interterritorial matrix?
-The matrix which lies in between chondrocytes and their lacunas
23
How is the ECM of elastic cartilage similar/different from that of hyaline cartilage, and what extra feature does this add?
-ECM made of hyaluronic acid and protein aggregates providing resilience
-Contains many elastic fibres conferring elasticity upon the cartilage
24
What colour is elastic cartilage in FRESH tissue?
-Yellowish
25
Where is elastic cartilage found in the body?
-Pinna of the ear
-Eustachian tube
-Epiglottis
-Auditory meatus
26
Does hyaline cartilage or elastic cartilage have more abundant chondrocytes?
-Elastic
27
What cell type(s) does fibrocartilage contain?
-Chondrocytes and fibroblasts (in relatively low numbers)
28
Why is fibrocartilage different from hyaline and elastic cartilage?
-It is a mixture of dense irregular connective tissue and hyaline cartilage
29
Does fibrocartilage have a surrounding perichondrium?
-No
30
Describe the distribution of cells within fibrocartilge
-Often found in rows or isogenous groups
-Few
31
What fibres does fibrocartilage contain?
-TI and TII collagen
32
How are the fibres arranged in fibrocartilage? Relate the structure to its function
-Fibres run in parallel with direction of force exerted upon it
-Provides high tensile strength and non-compressibility
33
What is the main function of fibrocartilage?
-Shock absorber and resistance of shearing force
34
Where is fibrocartilage located in the body?
-Intervertebral discs
-Sternoclavicular and temperomandibular joints
-Menisci of the knee joing
-Pubic Synthesis
-Ethesis
35
What is ethesis?
-Point of attachment of tendon to bone
36
Which type of cartilage calcifies with age?
-Hyaline
37
Which cartilage is the most common?
-Hyaline
38
In general, what are the three constituents of bone?
-Cells
-ECM
-Fibres
39
What is specific about the ECM of bone?
-Integrated with mineral salts, particularly calcium phosphate for rigidity and hardness
40
How is bone specialised for its function?
-High mechanical strength with minimal weight
41
Name the different groups of bones
-Long bones
-Short bones
-Flat bones
-Sesamoid bones
42
What are the two types of bone?
-Compact
-Spongy (Cancellous/trabecular)
43
What is the macroscopic histiological appearance of compact bone?
-Dense bone with no cavities
44
Where is compact bone found?
-External surfaces of bones
45
Microscopically, into what is compact bone arranged?
-Into osteons
46
What are osteons?
-Concentric lamellae of bone arranged around a central haversian canal, joined to other osteons, periosteum and bone marrow by volkmann canals
47
What do haversian canals carry?
-Blood vessels, lymphatics and nerves
48
What is cementing substance?
-A thin homogenous layer of amorphous material between osteons
49
Are volkmann canals surrounded by concentric lamellae?
-No
50
What are interstitial lamellae?
-Remnants of lamellae which used to be concentrically arranged around an osteon have been remodelled
51
What is the macroscopic structure of cancellous bone?
-Interconnecting network of cavities, filled with bone marrow separated by numerous irregular trabeculae
52
What is the microscopic structure of trabeculae?
-No haversian systems
-Lamellae not arranged in concentric circles but irregularly
53
How does trabecular bone receive nutrients?
-By diffusion from the marrow
54
What is periosteum?
-Vascular connective tissue which surrounds bone
55
What cell types are found in bone?
-Osteoblasts (which develop into osteocytes)
-Osteoclasts
56
What is the function of osteoblasts?
-Lay down new osteiod in bone remodelling
57
What is the function of osteoclasts?
-To resorb bone during bone remodelling
58
How do osteoclasts exert their action?
-Through H+ and lysosomal enzymes
59
In what do osteocytes lie?
-Lacunae
60
How are osteocytes arranged in immature and mature bone?
-Immature-> fairly randomly arranged
-Mature-> in the concentric lamellae
61
What is different about the lacunae of bone to lacunae of cartilage?
-Radiate canaliculi which anastomose with canaliculi of other lacunae
62
What is the function of canaliculi?
-Permit osteocyte cytoplasmic processes and passage of ions and nutrients to those osteocytes which lay far away from the artery
63
What is the sheath of neumann?
-fine fibrous tissue which lines lacunae and canaliculi
64
What must happen to bone in order for it to be histologically viewed?
-Decalcified which kills organic material
or
-Ground
65
Describe the action of bone remodelling
-Osteoclasts resorb bone through H+ and lysosomal enzymes which forms a cutting cone which runs parallel to the direction of the haversian canal creating a resorption cavity, osteoclasts lie in the resulting depression
-Osteoblasts deposit osteoid in sucessive lamellae creating a closing cone, filling the resorption cavity with new bone
66
Why can the bone resist fracture until a certain point?
-High tensile strength
-Degree of flexibility- lamellae can slip relative to one another before excessive force causes fracture
67
What are the four stages of bone repair following a fracture?
-Haematoma formation
-Fracture repair
-Bony callus formation
-Bone remodelling
68
Describe haematoma formation following a fracture
-Blood vessels in bone and periosteum break
-Haematoma (mass of clotted blood) forms
-Cells at periphery of fracture die due to lack of blood supply
-Removed by macrophages
69
Describe fracture repair following haematoma in a bone fracture
-New blood vessels infiltrate haematoma
-Procallus of granulation tissue (tissue rich in fibroblasts and capillaries) forms
-Fibroblasts produce collagen fibres which span the break, others differentiate into chrondrocytes and form a sleeve of hyaline cartilage across the break
-An externally buldging fibrocartilagineous matrix splints the bone
70
Describe bony callus formation after procallus formation following a fracture
-Trabeculae develop and a spongy callus is formed
-Edochondral ossification replaces cartilage with bone
-Fibrocartilagineous callus is know a hard bony callus of cancellous bone
-Continues for 2 months until hard union is formed
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