MSK Flashcards
1
Q
how many bones in adult vs children
A
adult 206
children 300
2
Q
5 functions of bones
A
- Provide shape & support of the body
- Enable movement
- Protect vital organs
- Production of blood cells (hematopoiesis)
- Mineral homeostasis & storage (i.e. calcium, phosphate, Mg)
3
Q
what are the 4 major bone structures
A
- bone cells
- collagen fibers
- ground substance/gelatinous material
- crystalized minerals
4
Q
what does bone cells do?
A
to grow, repair, synthesize new tissue and resorb old bone tissue
5
Q
what does collagen fibers do?
A
gives bone its tensile strength
6
Q
what is the Gelatinous Material (ground substance) in bones
A
medium between bone and blood vessels
7
Q
what does crystalized minerals do in bones?
A
provide rigidity
8
Q
what are the 3 types of bone cells?
A
osteoclasts
osteoblasts
osteocytes
9
Q
what is osteoclasts?
A
Large, multinucleated cells with ruffled borders
10
Q
osteoclasts riginate from
A
hematopoietic stem cells
11
Q
What’s the major function of osteoclasts?
A
breakdown bone
12
Q
Osteoclasts resorb bone by secreting
_____________
A
hydrochloric acid, acid proteases and MMPs (matrix metalloproteinases) – digest collagen, dissolve bone matrix
13
Q
What’s osteoblasts?
A
Mononuclear cells
bone forming cells
14
Q
Where does osteoblasts originate from ?
A
mesenchymal stem cells (MSCs)
15
Q
Osteoblasts active on _____surface of bones, form a ______ layer of cells
A
outer surface of bones, form a single layer of cells
16
Q
osteoblasts produce and deposit ______
A
Produce and deposit osteoid (unmineralized portion of bone matrix)
17
Q
osteoblasts also produce ____
A
Produce hormones (i.e. prostaglandins), ALP and other matrix proteins
18
Q
Osteoblasts that become surrounded by this new matrix differentiate into
A
osteocytes
19
Q
___ is the most abundant bone cells
A
osteocytes
20
Q
what is osteocytes?
A
transformed osteoblasts or mature bone cells
21
Q
osteoctyes are located in ____
A
Imprisoned within the mineralized bone matrix (lacuna)
22
Q
osteocytes have _____
A
dendrites which extend into canaliculi & secrete substances
23
Q
what’s the function of osteocytes
A
Help to maintain bone by signaling osteoblasts & osteoclasts to form and resorb bone
24
Q
osteocytes also act as what type of receptors?
A
‘mechanoreceptors’ and can detect mechanical stress on bone, hormonal imbalance
25
What is the bone composition?
35% organic, 65% inorganic, 5% water
26
what's the organic materials of bone?
Collagen fibers (provide bone strength)
Synthesized & secreted by osteoblasts
27
what's the inorganic materials of bone?
Calcium, Phosphate minerals
28
what does proteoglycans do?
Strengthen bone, form compression-resistant networks between fibrils
Control transport of calcium in bone
29
what are the three phases of bone remodelling
phase 1. activation
phase 2. resorption
phase 3. formation
30
what happens in the phase 1 of bone remodelling
A stimulus (i.e. physical stressor, increased PTH secretion) activates osteocyte cell death (apoptosis)
31
what happens phase 2 of bone remodelling
osteoclasts gradually digest bone mineral matrix & leave behind a “resorption cavity”
32
what happens in phase 3 of bone remodelling?
the laying down of new bone by osteoblasts which line the walls of the resorption cavity
33
Successive layers _____ in compact bone are then laid down until the resorption cavity is ____________
Successive layers (lamellae) in compact bone are then laid down until the resorption cavity is reduced to a narrow Haversian canal
34
RANKL is a ________ that is produced by _______
RANKL is a transmembrane protein that is produced by osteoblasts
35
RANKL binds to signalling receptors _____on the surface of ________
RANKL binds to receptors RANK on the surface of osteoclasts
36
When RANKL binds to RANK it activates ________
When RANKL binds to RANK it activates osteoclasts and the processes of bone resorption
37
________ is a cytokine produced by ________ and acts as a ‘decoy receptor’ inhibiting the binding of ________
Osteoprotegerin (OPG) is a cytokine produced by osteoblasts and acts as a ‘decoy receptor’ inhibiting the binding of RANKL/RANK
38
two types of bones
compact (corticol) bones 85%
spongy bones 15%
39
What's the basic structure of the compact bone?
Haversian system
40
Haversian canal is surrounded by rings of matrix called
lamellae
41
Between the matrix ring osteocytes are located in the _____
lacunae
42
Canaliculi
are small channels that radiate from the lacunae to Haversian canal - provide a passageway through the hard matrix
43
Haversian canal carries _______
blood, lymphatic vessel and nerve branches
44
spongy bones does not have ___
no Haversian systems - consists of a network of trabeculae
45
Spaces between trabeculae filled with _________
red bone marrow (hematopoietic stem cells)
46
What's periosteum
Thin double-layer of connective tissue
47
what's the function of periosteum?
Supplies blood & nutrients to bone
48
49
What's in the outer layer of periosteum
Outer layer (Fibrous):
- Blood vessels, nerves, lymphatics
- Blood vessels enter through channels (Volkmann canals)
49
What's in the inner layer of periosteum?
Inner layer (Cellular):
- Lies directly on bone
- Contains osteoblasts that function in both growth & repair
49
Bone classified by shapes (4 types)
Long: primarily consist of compact bone
Short (cuboidal): primarily consist of spongy bone
Flat: Thin, flattened, slightly curved
Examples: Cranium,
Irregular: Complex shapes & cannot be classified as above, primarily consist of spongy bone
50
What's a joint?
A joint is where two or more bones come together
51
Structural classification of joints
- Fibrous
- Cartilaginous
- Synovia
52
Joints classified by degree of movement
Synarthrosis (immoveable)
Amphiarthrosis (slight moveable)
Diarthrosis (Freely moveable)
53
Types of Synovial joint and examples
Plane (between tarsal bones of foot)
Hinge (elbow)
Pivot (top of neck)
Condyloid (wrist)
Saddle (thumb)
Ball & socket (shoulder, hip)
54
What's a joint capsule?
Connective tissue that covers the ends of bones where they meet in the joint
55
What's the out layer of a joint capsule?
interlacing bundles of white fibrous tissue
56
What's the inner layer of a joint capsule?
synovial membrane, highly vascular
Supplied with nerves, blood and lymphatic vessels
57
What are the two layers of a synovial membrane
vascular layer (subintima)
cellular layer (intima)
58
What's in the vascular layer of the synovial membrane
Fibrous connective tissue, elastin fibers, fat cells, fibroblasts, macrophages & mast cells
59
What are the two types of synovial cells in the cellular layer of the synovial membrane?
Type A: Ingest and remove bacteria/debris via phagocytosis
Type B: Secrete hyaluronate (gives synovial fluid its viscous quality)
60
the joint cavity contains____ &______
Contains free floating synovial cells & leukocytes
61
what's the composition of a articulate/hayline cartilage
Chondrocytes (cartilage cells) + Intercellular matrix (collagen, protein polysaccharides, water)
62
What's in the surface, middle, and bottom layer of a articulate cartilage?
Surface layer - collagen fibers run parallel to joint surface (compacted into a dense protective mat)
Middle layer - fibers are tangential to surface to absorb force of weight bearing
Bottom layer - fibers are perpendicular to surface to resist shear forces
63
articulate/hyaline cartilage dose not have ___ & __, therefore are ____
No blood or lymph vessels or nerves (insensitive to pain; regenerates slowly)
64
What's a ligament and what's the function of it?
Fibrous tissue which connects bone-to-bone; provide stability to joints
65
What's a tendon and what's its function?
Tough fibrous connective tissue which connects muscle to bone; withstand tension
66
what are the 3 types of cartilage and their examples?
Elastic (outer ear)
Hyaline (wall of trachea)
Fibrous (very strong - intervertebral discs of spine)
67
_______is the protein found in cartilage (gelatin-like, forms the matrix)
chondrin
68
there are apprx ___ muscles in the human body
600
69
At birth ~ ____of a child’s body weight is muscle mass; steadily increases and constitutes ____of adult weight
At birth ~ 25% of a child’s body weight is muscle mass; steadily increases and constitutes 40% of adult weight
70
What's the composition of muscle?
Composed of 75% water, 20% protein, 5% organic/inorganic compounds
71
3 types of muscles and their functions
Skeletal muscles: striated, multi-nucleus, voluntary control
Smooth muscles: non striated, single-nucleus, involuntary control
Cardiac muscleS: striated, single nucleus, involuntary control
72
Each skeletal muscle has 3 layers of connective tissue:
1.Epimysium: Wraps surface of muscle (below fascia) and extends inwards; Tapers at each end to form tendon
2. Perimysium (middle layer): Continuation of epimysium into muscle, groups muscle fibers into bundles of fascicles
3. Endomysium: Surrounds and wraps each of the fascicles
73
What's a fascia?
Casing of thick connective tissue that surrounds and separates each muscle, holding it in place (over the epimysium)
74
Muscles are composed of ____ and these cells contain chains of ______
Muscles are composed of myocytes and these cells contain chains of myofibrils (muscle fibers)
75
actin is ___ filament
thin
76
myosin is ___ filament
thick
77
____ contains protein tropomyosin and troponin
actin (thin filament)
78
____ is the basic contractile unit of myofibril
basic unit of muscle
sarcomere
79
what gives muscle its striated appearance?
sarcomere
80
Sarcomeres are composed of the proteins (4)
actin, myosin, titin, nebulin (actin binding protein)
81
myofibril consist of __ & __
actin and myosin
82
calcium are released from ___ during muscle contraction
sarcoplasmic reticulum
83
what are the 4 steps of muscle contraction?
1. excitation
2. coupling
3, contraction
4. relaxation
84
what's troponin?
a globular protein located on thin filament; Troponin in presence of calcium promotes actin-myosin activation
85
what happens during coupling?
Migration of calcium to myofilaments
86
what's tropomyosin?
a thin filament protein; Blocks binding sites on actin, prevents cross-bridge formation & muscle contraction
87
What happens during cross-bridge formation?
cross-bridge formation occurs when calcium ions bind to troponin, causing tropomyosin to move away from the myosin-binding sites on actin, exposing them for myosin heads to bind and initiate muscle contraction.
88
what are sesamoid bones?
Sesamoid bones are unique as they develop within tendons rather than from cartilage like long or flat bones.
89
what are pneumatic bones?
air spaces within bones
