Bones, joints and cartilage Flashcards
1
Q
Muscoskeletal system comprised of
A
Skeleton, muscles and accessory tissues which together allow locomotion and articulation
ie bone, cartilage, joints, ligaments, tendons, nerve fibres and BVs
2
Q
2 main tissue types the skeleton is made up of
A
bone and cartilage
3
Q
Bone 2 types
A
compact (exterior) and trabecular (interior)
4
Q
bone shapes
A
long, short, flat (slightly curved and irregular
5
Q
bone is encased with
A
fibrous periosteum (blood supply and nutrients)
6
Q
3 main types of cartilage
A
hyaline, fibro and elastic
7
Q
cartilage is sometimes encased within
A
fibrous perichondrium
8
Q
Hyaline
A
growth plate, joint surfaces and temporary scaffold
nose, ribs and larynx
9
Q
Fibrocartilage
A
invertebral discs, menisci (pads) in joint spaces
no perichodrium
Found in areas which must withstand lots of pressure
10
Q
elastic cartilage
A
external ear, epiglottis and larynx
stretchy
11
Q
bone functions
A
support, protection, attachment (locomotion), store minerals
Haematopopoiesis- produces RBCs
Lipid storage
12
Q
Bone water content
A
low
13
Q
Bone is made up of
A
minerals
type I collagen
proteoglycans/glycoproteins
14
Q
cell types in bones
A
osteoblasts (form bones)
osteocytes (abundant)
osteoclasts (bone resorbing)
15
Q
Cartilage function
A
template for bone formation, growth of long bones, smooth, articulating joint surface
16
Q
water content in cartilage
A
high
17
Q
Cartilage is made up of
A
type II collagen
Proteoglycans
Glycosaminoglycans
Glycoproteins
18
Q
Cell types in cartilage
A
chrondoblasts
chrondocytes
19
Q
Axial skeleton
A
bones of the skull, vertebral column and ribs
20
Q
Appendicular skeleton
A
bones of limbs, pelvis, scapula and clavicle
21
Q
Short bones
A
support and stability, little to no movement
cube like
hands and feet
22
Q
Flat bones
A
thin and flat
Can be a bit curved
Points of attachment for muscle or protect internal organs
23
Q
Irregular bones
A
don’t fit other categories
Complex shape eg bones in the face
24
Q
Long bone
A
located in the appendicular skeleton
25
anatomy of a long bone
includes diaphysis, epiphysis, spongy bone, epiphyseal line, metaphysis, fatty tissue, periosteum
26
Diaphysis
shaft of long bone
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Epiphysis
at each end. Proximal and distal
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spongy bone
found in the epiphysis. Contains bone marrow for rbcs
29
Epiphyseal plate/line
depending on stage of development
Becomes line when fully developed
Marks where proximal epiphysis starts
30
Metaphysis
contains the medullary cavity which is the hollowed out core of the bone
31
Fatty tissue
energy store
| aka yellow marrow
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Periosteum
outside the bone
| membrane
33
endosteum
lining inside of medullary cavity
| both membranes
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Whats at the end of the bone
articular cartilage
| Allows joints to move smoothly
35
Microanatomy of a long bone
basic functional unit of long bone is the osteon
Rings around it referred to as concentric lamellae- made up of layers of osteocytes
Canal in the centre where blood vessel is located
Orientation of the lamellae run in opposite directions i each layer to give bone ability to withstand impact
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Central canal
runs parallel to osteon
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Perforating canal
runs perpendicular to osteon
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cannaliculi
holds together osteocytes in the lacuna
| Deliver nutrients and oxygen to osteocytes
39
Trabecular (spongy) bone
here the bone isn't solid, instead filled with holes connected by thin rods/plates of bone tissue
Trabeculae have no blood vessels or central canal
Contains lamella like osteon, but lamella are parallel
Matrix inside which contains the lacuna which contains osteocytes
Space for red bone marrow between trabeculae
SPongy bone has no central canal, so obtains nutrients through pores in the bone surface
40
Osteogenic cells
undifferentiated
HIgh mitotic activity
In periostium and bone marrow
GIve rise to osteoblasts
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Osteoblasts
Found in periostium and endostium
Growing portions of bone
Responsible for forming new bone
Don't divide but synthesise and secrete organic compounds and ca salts
42
Osteocytes
formed from osteoblasts
Mature bone
Located in the lacuna
Maintain mineral concentration of the bone matrix
43
Osteoclasts
degrade bone
Cause bone resorption
They are a form of macrophage and don't originate from osteogenic cells
44
bone development aka
ossification
45
ossification has 2 form depending on the type of bone that is formed
intramembranous ossification and endochronal ossification
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skeleton develops from
The embryonic mesenchyme:
- loosely packed, unspecialised cells in a gel-like matrix
- derived from the embryonic mesoderm
47
Mesenchymal cells migrate and form
condensations- small clusters
| Prefigure sites of bone development
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Intramembranous ossification
bone forms directly within the condensation
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Endochronal ossification
most bones
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Cartilage template (analage )forms within the condensation
The cartilage analage is subsequently replaced by bone
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50
Intramembranous ossification process step 1
Cells come together and start aggregating and replicating, then differentiate into osteoblasts. The osteoblasts come together to form an ossification centre
Cells release osteoid (unmineralized bone)
Only happens at the middle of the ossification centre, so osteoblasts become trapped in the centre and differentiate into osteocytes
51
Step 2 IO
After a few days the osteoid begins to hardens and calcifies to form bone
After this the osteoid continues being deposited in a random fashion around blood vessels
52
step 3 IO
trabeculae form
53
step 4 IO
development of periosteum
Lamellae of of compact bone begins to form which replaces the trabeculae on the outside edge.
It gets deposited in layers and the spongy layer is still there
The osteoblasts stay on the outside surface of the bone- help remodel it when necessary
54
Endochrondal ossification step 1
Chrondocytes at center of the growing cartilage model enlarge and then die as the matrix calcifies
55
Step 2 EO
Stem cells divide to form osteoblasts which cover the shaft of the cartilage in a thin layer of bone
56
Step 3 EO
Blood vessels penetrate the cartilage and new osteoblasts form the primary ossification center
57
Step 4 EO
Bone of shaft thickens, and cartilage near each epiphysisis replaced by shafts of bone
58
Step 5 EO
Blood vessels invade the epiphyses and osteoblasts form secondary ossification centres
Secondary ossification complete: cartilage totally replaced by bone except in 2 places- surface of epiphyseal
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When is IO
commences in week 6 of gestation
60
When is EO
occurs in the foetus after 8 weeks of development
61
Post natal growth in length: epiphseal plate
| go over
1 new cartilage is produced on the epiphyseal side of the plate as the chrondocytes divide and form stacks of cells
As the chrondocytes divide and align in columns, the cartilage expands towards the epiphysis and the bone elongates
2 Chrondocytes mature and enlarge
3 Matrix is calcified, and chrondocytes die
4 The cartilage on the diaphyseal side of the plate is replaced by bone by osteocytes. Osteoclasts erode the old cartilage
Net result is that plate remains same in thickness, with elongation of the bone
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Post natal growth in width: apposition
osteoblasts deposit new bone on the outside of the bone shaft, and the osteoclasts break down tissue from the medulla to mainatin thickness of the bone
63
Bone remodelling step 1
Resting step- all the lining cells that are inactive osteoblasts are attached to the bone surface. Factors like microfracture and release of certain substances eg hormones can activate the lining cells. These cells interact with receptors that trigger pre-osteoclast fusion and form multi nucleate osteoclasts
64
Bone remodelling step 2
Osteoclasts gather together and begin to dissolve the bone. First they dissolve the matrix (acidification) and then release lysozomal enzymes to degrade organic components of the bone
Once dissolved to the required extent, undergo apoptosis to prevent excess resorption
65
remodelling step 3
Reversal
Cells remove the debris produced during resorption
Release of growth factors- recruit osteoblasts
66
remodelling step 4
Bone formation
Once osteoblasts are generated, alkaline phosphatase is produced to help form a new bone matrix
Matrix mineralised with calcium and P to form new bone and it returns to the resting phase
67
Bone mass in women
Osteoclast apoptoss is regulated by oestrogen so when oestrogen levels decrease, osteoclasts can live longer and breakdown more bone
68
In old people
trabeculae thinner, fewer and more widely spaced
69
Bone regeneration: fracture healing step 1
Blood released from damaged blood vessels forms a hematoma
70
BR 2
internal callus forms between ends of bones and the exteral callus forms a collar around the break
71
BR 3
woven, spongy bone replaces the internal and external calluses
Callus ossification
72
BR 4
bone remodelling
| Compact bone replaces woven bone, and part of the internal callus is removed, restoring medullary cavity
73
Joints
Occur at the joins between bones
synovial, fibrous, cartilaginous
Largest and most important are synovial
74
6 subtypes of synovial joint
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planar
hinge
pivot
condyloid
saddle, ball and socket
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75
Joint movement
X axis for up and down
Y for side to side
Z for 3D
76
Uniaxial joints
move along a single axis
77
Biaxial
move about 2 distinct axis
78
Simpified structure of a synovial joint
articular cartilage covering the ends of the bones
- smooth, lubricating surface- resists compression
Bilayered joint capsule: outer fibrous and inner elastic
- fibrous layer attaches to the periosteum of the articulating bone
- inner synovial membrane : site of production of the synovial fluid
a joint cavity filled with viscous synovial fluid
