Bone Flashcards
1
Q
State the difference b/n ‘bone’ and ‘bones’
A
"Bone = a type of connective tissue Bones = organs made up of bone tissue"
2
Q
State the functions of bones (5)
A
”- Support
- Facilitate movement
- Protection (of internal organs)
- Production of blood cells
- Storage and release of minerals and fat”
3
Q
Long bone Internal Structure
A
- medullary cavity surrounded by trabecular (spongy) bone, further encapsulated in cortical (compact) bone
4
Q
Long bone Appearance
A
”- cylinder-like shape
- longer than it is wide”
5
Q
Long bone Function
A
”- leverage
- contains red blood marrow: produces blood cells
- contains yellow blood marrow: stores triglycerides (fats)”
6
Q
Long bone Examples
A
”- humerus
- femur
- radius
- ulna
- fibula”
7
Q
Short bone Internal Structure
A
”- no medullary cavity
- mostly spongey bone surrounded by cortical bone”
8
Q
Short bone Appearance
A
”- cylinder-like shape
- longer than it is wide”
9
Q
Short bone Function
A
”- leverage
- contains red blood marrow: produces blood cells
- contains yellow blood marrow: stores triglycerides (fats)”
10
Q
Short bone Examples
A
”- humerus
- femur
- radius
- ulna
- fibula”
11
Q
Irregular bone Appearance
A
- complex shape
12
Q
Irregular bone Function
A
”- protect internal organs
- allow flexibility
- provide support”
13
Q
Irregular bone Examples
A
”- vertebrae
- sacrum”
14
Q
Sesamoid bone Appearance
A
”- small
- round”
15
Q
Sesamoid bone Function
A
- protect tendons from compressive forces
16
Q
Sesamoid bone Examples
A
”- patella
- fabellae”
17
Q
Flat bone
A
”- no medullary cavity
- 2 layers of compact bone surrounding either trabecular bone/air”
18
Q
Flat bone
A
”- thin
- curved”
19
Q
Flat bone
A
”- point of attachment for muscles
- protect internal organs”
20
Q
Flat bone
A
”- cranial bones
- sternum
- scapula”
21
Q
State the two types of bone membranes (in long bones)
A
”- periosteum
- endosteum”
22
Q
Periosteum Location in long bone
A
“outer surface of the bone
(peri– = “around”/“surrounding”) [except where the epiphysis meets other bones to form joints]”
23
Q
Periosteum Function
A
Function
24
Q
Periosteum Osteolytic/Osteogenic
A
Osteogenic & Osteolytic
25
Periosteum Number of layers
2
26
Endosteum Location in long bone
"lines the medullary cavity
| (end- = “inside”; oste- = “bone”)"
27
Endosteum Function
acts as a location for bone growth, repair, & remodeling
28
Endosteum Osteolytic/Osteogenic
Osteogenic & Osteolytic
29
Endosteum Number of layers
1
30
Define 'osteogenic'
able to produce new bone cells
31
Define 'osteolytic'
able to remove old, unwanted bone
32
State the function of osteocytes
maintains bone tissue; maintains the mineral conc. of the matrix via secretion of enzymes
-responsible for signalling and maintaining bone structure
33
State the function of osteoblasts
bone formation; become osteocytes
34
State the function of osteogenic cells
undifferentiated stem cell; develops into osteoblasts
35
State the function of osteoclasts
bone resorption
36
State the location of osteocytes
entrapped in matrix; located in lacuna, surrounded by bone tissue
37
State the location of osteoblasts
growing portions of bone, including periosteum and endosteum
38
State the location of osteogenic cells
deep layers of the periosteum and the marrow
39
State the location of osteoclasts
bone surfaces and at sites of old, injured, or unneeded bone
40
Define 'osteon' (a.k.a Haversion system)
structural unit of cortical (compact) bone
41
Each osteon is composed of rings of calcified matrix called...
lamellae (singular = lamella)
42
Compare Haversion (/central) canals v.s Volkmann's (/perforating) canals
The Haversian canal runs down the center of each osteon, containing blood vessels, nerves, & lymphatic vessels. These vessels & nerves branch off at right angles through Volkmann’s canals, to extend to the periosteum & endosteum.
43
Describe 'articulation'
where two bones meet
44
Describe 'projection'
an area of a bone that projects above the surface of the bone (raised markings)
45
Describe 'holes'
an opening/groove in the bone that allows blood vessels and nerves to enter the bone
46
State the density & colour of air
"- least dense
| - black"
47
State the density & colour of bone
"- dense (cortical bone is the most dense)
| - bright white"
48
State the density & colour of soft tissue
"- less dense than bone
| - dark on radiograph (darker than bone but not as dark as air/fat)"
49
State the density & colour of metal
"- dense
| - bright white"
50
Define 'ossification'
the process in which bone is created
51
State the 2 types of ossification
"- intramembranous ossification
| - endochondral ossification"
52
Outline intramembranous ossification
"- a process by which undifferentiated cells specialize into bone-forming cells, which then lay down the matrix of the bone tissue w/i which osteocytes (the resident cells of bone tissue) are created
- mainly used to form flat bones, clavicles, and most cranial bones"
53
Outline endochondral ossification
"- a process which creates bone from a cartilage template/base; the process that replaces hyaline cartilage with bone tissue
- all other bone (not flat)"
54
Explain intramembranous ossification
"1. Undifferentiated mesenchymal cells cluster and differentiate into become osteoblasts to form an ossification center (which produces the first trabeculae).
2. Osteoblasts begin to secrete osteoid (towards ossification center)
- osteoid forms the basis for the extracellular matrix of bone tissue (responsible for hardness of bone)
3. The osteoblasts become trapped w/i the mineralized matrix (osteoid) that they've produced
- This causes osteoblasts to differentiate into osteocytes
4. Accumulating osteoid is laid down which forms woven bone
5. Vascularized mesenchyme condenses on the surface of the trabeculae and becomes the periosteum
6. Woven bone just under the periosteum is replaced with compact bone
7. Woven bone at the center is remodelled into mature spongy bone and its vascular tissue its becomes red marrow
"
55
Explain endochondral ossification (stage 1)
"- underlying mesenchymal cells differentiate into osteoblasts
- perichondrium becomes periosteum
- osteoblasts secrete osteoid against hyaline cartilage shaft, encasing it in the bone collar"
56
Explain endochondral ossification (stage 2)
"- chondrocytes hypertrophy
- chondrocytes calcify surrounding cartilage matrix blocking off the nutrient supply
- chondrocytes die and the matrix begins to deteriorate which opens up cavities"
57
Explain endochondral ossification (stage 3)
"- periosteal bud invades the internal cavities (consists of artery, vein, nerve, and lymphatics. Delivers osteogenic cells)
- spongy bone forms"
58
Explain endochondral ossification (stage 4)
"- osteoclasts break down newly formed spongy bone to open up a medullary cavity
- primary ossification centre expands into deteriorating cartilage (diaphysis elongates)
- secondary ossification centers begin to form at the epiphyses"
59
Explain endochondral ossification (stage 5)
"- secondary ossification centers undergo the same events as the primary ossification centers except the interior spongy bone is retained and no medullary cavity forms in the epiphyses
- the epiphyses ossify and hyaline cartilage is only found at the epiphyseal plates and on the epiphyseal surfaces"
60
Explain long bone formation
"1. Perichondrium lays down bone on cartilage in the diaphysis region via intramembranous ossification process
2. Cartilage at centre of shaft degenerates; vascularisation; Matrix becomes impregnated w/ calcium salts - Endochondral ossification
3. Process continues at the epiphyses of the long bone: cartilage template start to degenerate; epiphyses are vascularised; w/i the epiphyses region, the cartilage template is impregnated w/ calcium salts
4. There is now a cartilaginous region at the metaphysis —> growth plate"
61
State the location in long bone which is responsible for lengthwise growth
epiphyseal (growth) plate
62
Explain how long bone grows lengthwise
"1. A reserve pool of chondrocytes begin to divide/proliferate
2. The proliferating chondrocytes start to grow/hypertrophy
3. Once they've enlarged & hypertrophied, the hypertrophic chondrocytes then calcify and later become endochondral bone"
63
Explain how long bone grows its cross-section
"1. Additional bone is added to the exterior surface of the existing bone diaphysis (immature) bone
2. Osteoblasts in periosteum secrete new bone matrix beneath the periostial surface
- Bone is now thicker, however, is now more heavy and costly in terms of energy. Bone must be removed from the inner surface of the diaphysis.
3. Osteoclasts found in endosteum resorb away bone tissue from the centre of the diaphysis
- Now, left with bone with a much larger cross-section, however, does not carry excess weight (bone tissue)"
64
Explain the formation of osteons
"1. Periosteal surface: blood vessels travel in a particular direc., allowing bone to be formed, a new bone matrix to be laid down parallel to the direc. of the blood vessels.
2. Ridges are therefore produced on either side of the blood vessels, which are effectively lifts that ultimately join to produce the lamellae of the osteon.
3. As bones continue to be formed, the ridges become higher, and the channel in which the blood vessels run become deeper.
4. The ridges of bone eventually touch each other, either side of the blood vessel. Therefore, completed formation of the Haversion (central) canal & encircling lamellae."
65
Lamellar Production speed
slow
66
Lamellar When is it produced?
"during bone...
- growth
- remodelling"
67
Lamellar Structure/Arrangement
"- regular
- structured
- concentric arrangement"
68
Lamellar Strength
strong
69
Woven Production speed
fast
70
Woven When is it produced?
fracture healing
71
Woven Structure/Arrangement
irregular structure
72
Woven Strength
weak
73
Define 'bone remodelling'
a lifelong cyclical process of bone removal and addition
74
Define 'bone modelling'
the process of bone shape change in response to the loads imposed
75
Function of remodelling? (3)
"- maintain mechanical strength
- response to mechanical demands (Wolff's Law)
- mineral homeostasis - provide access to calcium and phosphorus stores"
76
Explain why bone remodelling is defined as a 'cyclical process'
"1. Reversal: area is populated by osteoblasts
2. Formation: osteoblasts synthesize organic matrix and regulate mineralisation of matrix. Osteoblasts entrapped in matrix become osteocytes
3. Osteoclasts form and attach to bone matrix
4. Resorption: Osteoclasts secrete enzymes which break down bone. Osteoclast apoptosis.
5. Repeat steps 1-5"
77
State which hormones are responsible for the cessation of skeletal growth
"- oestrogen
| - testosterone"
78
Discuss nutritional and hormonal factors that can affect bone growth
"- absorption of dietary calcium and phosphate salts depend on calcitriol
- calcitriol is a hormone that is only produced in presence of vitamin D"
79
State 2 hormones responsible for calcium metabolism regulation
"- calcitonin
| - parathyroid hormone"
80
State 4 vitamins responsible for bone growth
"- vitamin C
- vitamin A
- vitamin K
- vitamin B12"
81
State 3 hormones responsible for bone growth
"- insulin
- growth hormone
- thyroxine"
82
In adults, the epiphyseal plate is composed of
bone tissue
83
In young, the epiphyseal plate is composed of
cartilage
84
Bone marrow is the site of (3)
"-site of fat stores
- site of blood cells store
- site of stem cells store"
85
How do arteries enter the bone
they enter via the nutrient foramen in the diaphysis
86
What do arteries pass through to supply calcified part of cartilage
the subchondral bone
87
What supplies the cortical bone
Haversian and Volksman canals
88
Trabecular bone is supplied via .....
bone marrow
89
What are osteons
They are collagen fibres that run in different directions in neighbouring lamellae. Different directions means more resistant to twisting force
90
State the functions of surface markings (4)
"-leverage
- muscle attachement
- response to strain within bone
- articulations with other bones"
91
Relationship between moment arm and force
large moment arms make it possible to life loads with smaller forces
