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Bone Flashcards

0
Q

Bone tissue (4)

A

Mineralised ecm - rigidity and hardness, resistant and light
Continuous remodelling
Bones, dentin, cementum

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1
Q

Supportive connective tissue?

A

Bone and cartilage

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2
Q

Functions of bone tissue (5)

A 
Skeletal - framework
Mechanical - intertion of tendons and ligaments
Protection of organs
Trophic - calcium storage
Hematopoietic - rbc formation
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3
Q

Component of bone and 2 types

A

65% calcium hydroxy apatite
23% col
10% water
2% non col proteins

Organic - resistance to tensile pression forces
Inorganic - rigid, hard

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4
Q

Bone destroyed - inorganic and organic component

A

Inorganic - loss of rigid and hardness - bone retain resistance but flexible

Organic - bone shape and size maintained - fragile like porcelain

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5
Q

Bone tissue classification? 2

A

Non lamellar - woven bone - intertwined (inferior vertebrates, fetal bones, fracture repair). Parallel fibres (birds)

Lamellar mature (compact) - outer shell flat bones, surface short bones, dia+epi(physis) of long bones
(Spongy) epiphysis of long bone, short bones
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6
Q

Primary bone (5)

A

In embryogenesis eg fetal bones
Irregular intertwined fibres
Progressive remodelling. Replaced with lamellar bone
Initially formed - bone fracture repair
Less mineralised - diff mechanical properties

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7
Q

Quick bone structure?

A

Osteon, interstial lamellae, inner-outer circumferential layer, harversian canal, osteocytes in lacunae, canaliculi sharpey fibres, periosteum bv

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8
Q

Purpose of canaliculi?

A

Osteocyte Communication at diff levels

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9
Q

Periosteum and endosteum contains?

A

Deep layer - Osteoblasts formed from osteoprogenitor cells -> generate new bone tissue
BV AND DCT
Outer, intermediate, deep layer
Sharpey fibres - perforating - collagen bundles enter into bone matric

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10
Q

Osteon (4)

3 types of canals in bone?

A

Concentric lamellae
0.9-1.2mm
5-20 lamellae
Canaliculi - communication between osteocytes

Canals - haversian, volkmann, canaliculi

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11
Q

System of lamellae?

A

Parallel fibres of collagen - increase strength - absorb diff mech stress

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12
Q

During bone remodelling?

A

Pre-existing osteons destroyed(interstitial lamellae), new ones formed.

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13
Q

Methods to study bone tissue (2)

A

Decalcified bone - inorganic component removed via acid. - stained with hande for soft tissue

Ground bone - remove cell and bv. Preserve organic, mineral component. Moethod : cut using saw. Ground to suitable thickness.lacunae + canaliculi = black

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14
Q

Lamellar spongy bone ( medullary cavities + trabeculated bone)
Where bone marrow located?

A

Epiphysis bone marrow only.
Cross section - lamellae, not true osteon, thinner. Same morphology of osteocyte.
Trabeculae - thin, irregular lamellae - osteocytes. Endosteum, no haversian canals, interconnected canaliculi, 3D structure,

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15
Q

Difference between periosteum and endosteum?

A

Endo - inner surface of bone cavities
Single layer osteoprogenitor cells
Thinner than periosteum. Provide nutrition to cells

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16
Q

Cells types on bone(5)

A

Osteoprogenitor
Bone lining on bone surface
Osteocytes - mature cells, not secrete matrix
Osteoblast - not divide - secrete matrix + collagen fibres - cuboidal cells
Monocytes -> Osteoclast - bone reabsorped. Ruffled border

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17
Q

Osteoprogenitor cells?

A

Similar to fibroblast. 1 layer surface on perio/endo steum

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18
Q

Osteoblast

A

Cuboidal. Well developed golgi rer
Produce ecm, recptor for pht- stimulated - osteoblast stim osteoclast
In matrix = osteocytes

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19
Q

Bone lining cells

A

Surface of bones where no remodelling,derived from osteoblasts,
Support osteocytes
Regulate calcium in matrix

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20
Q

What directly stim osteoclasts?

A

Calcitonin

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21
Q

Osteocytes

A

In lacunae, canaliculi, non mineralised - allow movment of nutrients
Flat cel body
Mature, abundant, quintescent

Function - mechanotransduction - rel factors - mod preosteoblast activity

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22
Q

Osteocytes canaliculi

A

Gap junction. Nutrients via bv in central canal

Mechanotransduction- actin network - movement of nutirents

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23
Q

Osteoclasts

A

200-109um, multinucleated (syncitium), polarised cells
Monocyte linage
Podosome - adhesion - increase sa
Calcitonin receptor
Large no of golgi, rer, mito
Howship lacunae under cell
Lysosomes - h2co3 provide protons - acidic pump - activate lysosmal enzymes . Only under cell - therefore not dmg other portion of bone
Activated by factors released by osteoblasts (pth indirectly)

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24
Bone dev. Intramembraneous, direct
Form same histological structure as Mesenchyme - large no of vessels Differentiate into osteoblast - secrete matric - osteoid Osteoid not mineralised - become mineralised -> bone increase in size
25
Bone formation and mesenchyme?
Mesenchyme Cell proliferation - form condensed mesenchyme.
26
Direct and indrect ossification forms?
Direct - flat bones of skull, face and clavicle, embryo in the mesenchyme Indirect - cartilage - temp replaced by bonr Base of skull Vetebrate Bones of extremities + axial skeleton
27
Direct ossification mechanism?
Alkaline phosphatase - hydrolyse po4- Increase and high lvl of po4- Nanocrystal form in and around matrix vesicles Calcium hydroxyapatite surround collagen fibres
28
Mineralisation of bone tissue in direct oss.
Hardness of bone Osteoblasts deposit osteoid Deposition of calcium hydroxyapetite between collagen fibres
29
Indirect oss
Endochrondral. Most long and short bones Precursor model of cartilage - almost completely replaced with bone tissue Mineralisation of cartilage - removed - deposition of bone. Cartilage remain at articular surface
30
Endochrondral oss. Mesenchyme ->....
Condensed mesenchyme, hylaine cart, hypertrophic cart, calcified cart, chondrolysis, endochrondral oss (bv invade, invading mesenchyme diff into osteoblast -> deposit osteoid)
31
Which cell perform chrondrolysis?
Chrondrocyte
32
2 modalities of indirect oss.
Perichondral - surface of cart | Endochrondral - inside cart
33
Endochondral steps (5)
Bone cart form - cart model - interstial(length), appositional(width) growth. Chondrocytes central - enlarge, die - calcified matrix. Bone collar form Prim oss centre Chondrocytes hypertrophy -> lacuna Secondary oss centre form
34
Perichondral steps
Basic cart form Periosteum - osteoblasts cover surface in thin layer of bone Bv invade cart - new osteoblast form prim oss centre Medullary cavity - + more, diaphysis: bone replace cart Post birth - 2 oss centre. Secondary oss centre form. Epiphyseal plate - located in metaphysis
35
Outline of bone growth from embryo to matrix adult
Embryo 5-6 w - hyaline cart "" 6-8 w - periosteum form Fetal 8-12 w - prim oss centre form Post natal - cancellous bone, calcified cart Prepubertal - cancellous bone at ends Matrix adult - articular cartilage at ends
36
Length and grwoth of bone?
Growth until length achieved - epiphyseal cart completely replaced (metaphysis)
37
Bone xray - incomplete oss (2)
Epiphyseal line - black line - lack of mineralisation | Also determine age
38
Primary bone production
Occur during embryo dev + bone healing | Large no of osteocytes, interwoven collagen, less mineralisation
39
Seoncary bone formation
Mature bone -> osteons (lamellar compact bone)
40
Repair of fractured : 4 steps
Hematoma form - blood clot Callus form - soft callus (fibrocartiliginous) Bony callus form - hard callus Bone remodelling - spongy part of bony callus -> compact bone
41
Bone remodelling? Increase diameter, thickness,
Appositional growth Bone vessel on surface of bone - encircled by bones -> form lamellae - ultimately form harversian canal Oldest lamellae on outside. Newest = inside
42
Remodelling unit (2). 2 zones. 2 phases
Osteoclast/blast remodelling process 2 zones - closing : osteoblasts on inside - form new osteon - cutting cone : osteoclasts on inside Resorption phase : 2/4 weeks Formation phase : 4-6months
43
Bone tissue regukated by? Hormones, nutrients, exercise
Hormones - pth, caltitonin, gh Nutrients - calcium, vit d -> increase absorption of ca2+ by SI EXERCISE - mechanical stim - remodelling of bones - modify position of new matrix
44
What hormones: stim osteoblasts, stim/inhib osteoclasts, increase absoprtion of ca by si
Stim osteoblasts - gh, thyroxine, sex hormones Stim osteoclasts - pht Inhib osteoclasts - calcitonin Calcitriol - increase absorption of ca by SI
45
Osteoporosis
Increase osteoclasts - increased reabsorption - new bone - weaker - increased risk of fracture
46
Skeletal muscle - no. Of nuclei? Organisation of filaments in muscle fibres Where skeletal muscle found?
Multiple. Located beneath sarcolemma. Syncytium. Skeletal+cardiac = striate Skeletal - insert onto tendons - linked to bone - found in tongue, pharynx, esophagus, mimic muscles
47
How morphological unit of skeletal muscle derived?
From fusion of myoblasts (mononuclear,l undiff, no myofibrils) - myofibrils (filaments in parallel array) + other organelles. Striated perpendicular to longi cut
48
Muscle regen - satellite cells
Satellite cells surround muscle fibre - involved in muscle regen - fuse - myotubules form - replace lesions
49
Cardiac muscle -> lose myocytes?
No satellite cells -> no regen
50
Endo, peri, epi mysium
Endo - reticular fibres surround muscle fibres. Small bv and nerve parallel to fibres Peri - larger bv and nerves. Thicker ct. Fascicles -> function of muscle fibres as a whole. Epi - Sheath dct. Penetrated by Major bv and nerve supply.
51
In cross section and longi of skeletal muscle?
Cannot detect striations Polygonal cells Peripheral nuclei Longi : z lines, a i band, h zone, nucleus at periphery
52
Skeletal. Dark band? H band? Area of overlap? M line contains?
A band is dark and area of overlap. H band only thick filaments M line - proteins - maintain thick fil in correct position.
53
Size of thick and thin filament?
Thick :10-12nm | Thin : 5-7nm
54
Sarcomere proteins (3)
Titin - maintain thick filaments - correct arrangement in sarcomere Nebulin - non elastic - maintain correct length of thin filaments Actinin - bind actin to z line
55
G actin + f actin? | Myosin head?
Polymerisation of g actin form f actin req atp Myosin head - 2 peptides - active site attached to actin filament
56
Troponin (3) steric blocking mechanism
3 subunits TIC TNT - bind to tropomyosin TNI - bind to actin filament TNC - bind to calcium
57
Other muscle fibre proteins? (5)
Desmin - int fil - insert into costamere - link z lines Plectin - connect adjacent desmin Ab crystallin - heat shock protein - protect desmin from stress induced dmg Alpha-actinin - anchor actin to z-disk Dystrophin - links sarcolemma to actin. Mutation - muscular dystrophy. Vital in cell stability Tropomodulin - actin capping protein - prevent polymerisation
58
Structure and protein of m line
Maintain correct arrangement of myosin filaments Proteins - myomesin, m protein, schlemin Electron dense
59
Sliding filament theory?
Overlapping of thick and thin filaments
60
Mechanism of sliding filament theory?
Atp + myosin head- atp hydolysis - myosin head 90*, myosin bind to actin release adp + pi, myosin head -> 45*
61
Calcium released into.... | Atp bind to myosin head causes?
Via T tubules into sarcolemma | Atp bind to myosin head -> detachment from actin filamments
62
Rigor mortis? (3)
Stiffening of muscle after death - 24/48 hr muscle proteins broken down - allows muscle to relax. No oxygen - no atp - atp not bind to myosin head - unable to relax
63
Skeletal muscle triad
At boundary between A and I band. 2 terminal cisternae of sr 1 tubule H band = central portion of traid
64
NMJ, structure, toxins, disease
Large no of infoldings. Ach, Toxins - botulinum(block rel of ach), curare(block ach receptors), neostigmine(block removal of ach), neurotoxins(block ach receptors) Myasthenia gravis - auto immune disease. Attack ach receptors. Lost...
65
3 types of skeletal muscle fibres?
Type 1 - slow oxidative - red slow twitch Type 2a - fast oxidative glycolytic fibres - intermediate Type 2b - fast glycolytic fibres - white/pink - fatigue. Fast myosin atpase velocity. Lactic acid
66
Which stain to differentiate skeeltal muscle fibres
Succinate dehydrogenase
67
Type 1 skeletal muscle fibres
Slow sustained contractions. Large mito Myoglobin Large no of cappillaries Postural muscles of axial skeleton. Resisatnce to fatigue - oxygen remains - no lactic acid produced. Low glycogen level. Glucose completely used up.
68
Type 2 intermediate fibres
Many mito. Anaerobic and aerobic respiration. Fatigue. Generate high peak tension. Lower limbs. Contract similar to fast twitch
69
White slow twitch muscle fibres?
Easily fatigue. Low mito and capp Low myoglobin High no, of glycogen. Anaerobic respiration. Creatine phosphate pathway. Fast powerful contractions. Digit movements, extraocular muscles. Fine precise movements. Greater no, of NMJ than slow twitch.
70
Hypertrophy and atrophy (3 each)
Hyper - increase in muscle size, no. Of myofilaments. Stim by resistance training, testosterone, anabolic steroids Atrophy - reduction of muscle fibre size, cells smaller + size, due to pathology - removal of nerve, immobility, lack of use
71
Cardiac muscle tissue. Where? And joined by? Innervation? All layers of muscle(5)
Myocardium - heart contraction (cardiomyocytes) - joined by junctions (intercalated disks-dark lines) Innervation - autonomic nervous system Layers - pericardium - serosa cavity - epicarium - myocardium - endocardium
72
Cross section of cardiac and how different from SM?
Some nucleus(maybe multiple) seen, striated, granules -> presense of myofibrils SM NO graules, homogenous cytoplasm
73
Cardiomyocytes(2)
``` Elingated (100um) Rounded nucleus (sometimes 2) ```
74
What surrouds cardiomyocytes?
Ct -> bv therefore vascularised - cardiac bundle = avasular
75
Intercalated disks
EM -> desmosomes (strong adhesion) Longitudinal -> gap junction, calcium movement Transverse - adherens junctions - cadherin + b catenins Connect cardiomyocytes - mechanically, chemically, electrically - mass of cells contract together
76
Cardiomyocytes extras (2)
Mito seperate myofibrils | Adhering junctions bind actin at z-lines
77
Cardiac muscle - diads
Only one t tubule - larger than in skeletal muscle. At z lines.
78
Nuclei of cardiac and skeletal muscle?
Cardiac - at center | Skeletal - periphery
79
Cardiac muscle and heart conduction?
Purkinje fibres - modified muscle cells - (less myofibrils, less contraction, more conduction of impulse) - not specialsed for contraction. SAN -> AVN - ventricles
80
Sm - thick and thin filaments?
Thin - actin, tropomyosin, caldemon, calponin (last 2 are ABP) block myosin binding site Thick - 2 heavy and 4 light chains - myosin 2. Side polar thick filament. No central bare zone. Tapered bare ends.
81
Sm contractile proteins essential to regulation?
Alpha actinin - structural support to dense bodies Calmodulin - bind to ca - activates mlck Myosin light chain kinase - phosphorylates myosin light chain - therefore able to bind to actin filament
82
Which enzyme in sm, inactivates myosin?
Phosphatase - dephosphorylates
83
Dense bodies?
Anchor intermediate filaments, a-actinin and actin and myosin filaments to sarcolemma. Anaologs of z line in skeletal muscle
84
Sm - different types of contraction initiators?
Mechanical - myogenic reflex, passive stretching - open calcium channels Electrical - ach or noradrenaline - depolarisation - ca2+ channels open Chemical - hormones bind to receptors on pm. Second messenger pathway eg (IP3, g protein coupled, NO-cGMP pathways)
85
Smooth muscle cells in bv and uterus?
Secrete ct matrix. Perinuclear zone - rer and golgi Synthesise - col type 3+4, proteoglycans, elastin, adhesive glycoproteins
86
Sm surrounded by?
External lamina, except at gap junctions
87
Multi Adhesive glycoproteins(4). Which type of unassumed cells can synthesise?
Sm cells Osteopontin - bone - bind oateoclasts,ca and hydroxyapatite Laminin - basal lamina of all epithelial cells Tenascin - embryonic mesenchyme, wounds, tumours, musculotendinous junctions - modulation of cell attachment to ecm Fibronectin - ecm tissue, cell adhesion
88
Smooth muscle cells and t system? | Contraction of sm regulation?
No t system. Regulation by calcium, calmodulin, myosin light chain kinase system. Camincrease bind to calmoduline. Activate mlck. Phos of light chain in myosin, expose binding site of actin on myosin head.
89
Sm contraction maintained?
Long periods - latched state. Comparable to rigor mortis of skeletal muscle Bv - maintain contraction
90
Sm specialisation?
Slow prolonged - contraction, extended period. no fatigue No nervous stim = spontaneous contractile activity Other hormones stim sm contraction? Oxycytocin, adrenal med ~ epinephrine(nor)
91
Sm tissue shape, where found? Structural aspect?
Elongated fusiform. Nucleus central. Gi tract, male genital system, Ovary medulla No myofibrils - no striations - infoldings of sarcolemma - caveolae - also found in cardiac muscle.
92
Sm int filaments function
Vimentin and desmin - help contraction - pulling ends - shortening cell
93
2 types of sm innervation!
Single - 1 axon innervates sm in an area - gap junctions Multiunit - multi axons innervate axons in an area
94
Regenration of muscle cells?
Skeletal - satellite cells Cardiac - none Sm - mitosis eg( uterus, bv, stomach and colon,
95
Sm cells can develop from?
Fibroblasts, endothelial cells, pericytes
96
Which cells of seminiferous tubules of testis have contractile function?
Myoid cells

Histology (17 decks)

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