BONE Flashcards
1
Q
- an example of specialized connective tissue
- its ECM is different because its matrix hardens
a connective tissue characterized by a
mineralized extracellular matrix (abundance of
calcium and phosphate)
A
BONE
2
Q
Bone matrix contains mainly
A
type 1 collagen
3
Q
FOUR MAIN GROUP S OF
NONCOLLAGENOUS PROTEINS FOUND IN
THE BONE MATRIX
A
Proteoglycans
Multiadhesive glycoproteins
Bone specific, vitamin K dependent
proteins
Growth factors and cytokines, which are
small regulatory proteins
4
Q
contribute to the compressive strength of
bone
responsible for binding growth factors and
may inhibit mineralization
A
Proteoglycans
5
Q
what are the Multiadhesive glycoproteins
A
Osteonectin
Osteopontin
Sialoprotein I and II
6
Q
-
serves as a glue between the collagen
and hydroxyapatite crystals
A
Osteonectin
7
Q
mediates attachment of cells to bone
matrix
A
Osteopontin
8
Q
mediate cell attachment and initiate
calcium phosphate formation
A
Sialoprotein I and II
9
Q
what are the Bone specific, vitamin K dependent proteins
A
Osteocalcin
Protein S
Matrix Gla-protein (MGP)
10
Q
what are the Growth factors and cytokines, which are small regulatory proteins
A
Insulin like growth factors (IGFs)
Tumor Necrosis Factor (TNF-)
Transforming Growth Factor (TGF-)
Platelet Derived Growth Factors (PDGFs)
Interleukins (IL 1, IL 6)
Bone Morphogenic Proteins (BMPs)
11
Q
is now used clinically to induce bone growth after bone surgery involving large bone defects, spinal fusions, or implantation of graft materials
A
Recombinant human BMP 7
(osteogenic protein 1)
12
Q
BONE STRUCTURE consists of
A
Bone matrix
Periosteum
13
Q
BONE CELLS consists of
A
Osteoprogenitor Cells
Osteoblasts
Osteocytes
Osteoclasts
Bone lining cells
14
Q
–
contains spaces called lacunae connected
by a network of canaliculi
–
each lacunae contains a osteocyte which
osteocyte numerous processes extend into
small tunnels called canaliculi
A
Bone matrix
15
Q
–
consists of dense connective tissue, with a
primarily fibrous layer covering a more
cellular layer
–
bone is vascularized by small vessels that
penetrate the matrix from the periosteum
A
Periosteum
16
Q
cells derived from mesenchymal stem cells
give rise to osteoblasts
presursor cells of osteoblast
A
Osteoprogenitor Cells
17
Q
Osteoprogenitor Cells are found on the
A
external and internal surfaces
of bones and may also reside in the
microvasculature supplying bone.
18
Q
Osteoprogenitor Cells appear as
A
flattened or squamous cells
lightly staining
elongate, or ovoid nuclei
inconspicuous acidophilic or slightly
basophilic cytoplasm in growing bones
19
Q
requires a population of renewable
osteoprogenitor cells (osteoblast precursor
cells) that are responsive to molecular
stimuli that transform them into bone
forming cells
synthesis of osteoprogenitor cells (ig?)
A
Osteogenesis
20
Q
*
key factor that triggers
differentiation of osteoprogenitor cells
*
prompts the expression of genes that are
characteristic of the phenotype of the
osteoblast.
A
Core Binding Factor Alpha 1 (CBFA1)
21
Q
Osteoblasts located exclusively at the ____________, usually side by side in a layer
somewhat resembling a simple epithelium
A
surfaces of bone matrix
22
Q
synthesizes the ORGANIC components of
bone matrix
A
Osteoblasts
23
Q
Osteoblasts are polarized cells matrix components are secreted at the cell surface in contact with older bone matrix, producing a layer of new (but not yet calcified) material called _________ between the osteoblast layer and the bone formed earlier
A
osteoid
24
Q
During active matrix synthesis: osteoblasts
have a ________________ shape and
basophilic cytoplasm
A
cuboidal to columnar
25
During decline of synthesizing activity:
osteoblast ____________ and cytoplasmic
basophilia is reduced
flatten
26
found in cavities (lacunae) between layers
(lamellae) of bone matrix
mature form of osteoblast
less basophilic; less synthetic ability
Osteocytes
27
individual osteoblasts are gradually
surrounded by their own secretion and
become osteocytes enclosed singly within
spaces called
lacunae
28
cells are involved in maintaining the bony matrix and their death is followed by resorption of this matrix
Osteocytes
29
histologic properties of osteocytes
* are flat, almond-shaped cells
▪ exhibit a significantly reduced RER and Golgi apparatus and more condensed nuclear chromatin
30
transition from osteoblasts to osteocytes
the cells extend many long __________ which also become surrounded
by calcifying matrix
cytoplasmic processes
31
osteocyte and its processes occupy each
lacuna and the canaliculi radiating from it
32
Processes of adjacent cells make contact
via __________ and molecules are
passed via these structures from cell to cell
can provide nourishment for a chain of
about ten cells
gap junctions
33
TYPES OF OSTEOCYTES
Quiescent osteocytes
Formative osteocytes
Resorptive osteocytes
34
*
exhibit a paucity of rER and a markedly
diminished Golgi apparatus
*
an osmiophilic lamina representing mature
calcified matrix is seen in close apposition
to the cell membrane
Quiescent osteocytes
35
show evidence of matrix deposition and
exhibit c ertain characteristics similar to
those of osteoblasts.
*
rER and Golgi apparatus are more
abundant, and there is evidence of osteoid
in the pericellular space within the lacuna
Formative osteocytes
36
*
like formative osteocytes, contain
numerous profiles of endoplasmic
reticulum and a well developed Golgi
apparatus. More over, lysosomes are
conspicuous.
Resorptive osteocytes
37
multi nucleated giant cells involved in the
resorption and remodeling of bone tissue
*
come from series of hemopoiesis
Osteoclasts
38
Osteoclasts lie within enzymatically etched depressions or crypts in the matrix known as ________________ in bone undergoing resorption
resorption bays (formerly called Howship lacunae)
39
In active osteoclasts the surface against
the bone matrix i s folded into
irregular projections, which form a
ruffled border
40
without this structure there’s impaired resorption of bone
ruffled border
41
surrounding the ruffled border is a
_________________
between the osteoclast and the matrix in
which bone resorption occurs
subcellular pocket microenvironment
42
in to this subcellular pocket the osteoclast
secretes _____________ and other enzymes
and pumps protons, forming an acidic
environment locally for dissolving
___________ and promoting the
localized digestion of collagen
collagenase; hydroxyapatite
43
Osteoclasts have receptors for
_________ a thyroid hormone, but not for
parathyroid hormone.
calcitonin
44
Osteoblasts activated by PTH
produce a
cytokine called
osteoclast stimulating factor
45
–
characterized by dense, heavy bones
("marble bones")
–
osteoclasts lack ruffled borders, and
bone resorption is defective
Osteopetrosis
46
*
cells that remain on the bone surface when
there is no active growth
*
derived from those osteoblasts that
remain after bone deposition ceases
Bone lining cells
47
All cells except ________ originate from
the mesenchymal stem cells
osteoclasts
48
mesenchymal stem cells differentiate into
osteoprogenitor cells, osteoblasts, and finally osteocytes and bone-lining cells.
49
types of bone lining cells
Periosteal cells
Endosteal cells
Osteoprogenitor cells and bone lining cells
Osteoclasts
50
Bone lining cells on external bone surfaces
–
form the innermost layer of the periosteum
Periosteal cells
51
Bone lining cells on internal bone surfaces
Endosteal cells
52
–
line the marrow cavities, the osteonal
( canals, and the perforating
(Volkmann Volkmann’s) canals.
Osteoprogenitor cells and bone lining cells
53
bone lining cells that have a similar microscopic appearance
and are often difficult to distinguish from
each other.
Osteoprogenitor cells and bone lining cells
54
originate from hemopoietic progenitor
cells, which differentiate into bone
resorbing cells that also line bones
Osteoclasts
55
COMPONENTS OF BONE MATRIX
Inorganic material
Hydration shell
Organic matter
Calcium binding glycoproteins
56
represents about 50% of the dry weight of
bone matrix
Inorganic material
57
most abundant inorganic material found in the bone matrix
combination of calcium and phosphate
Hydroxyapatite
58
aside from hyrdoxyapatite, what are the other inorganic materials found in the bone matrix?
Bicarbonate
Citrate
magnesium
Potassium
sodium
amorphous (noncrystalline)CaPO4
59
a layer of water and ions forms around the
hydrated surface ions of hydroxyapatite
–
facilitates the exchange of ions
between the crystal and the body
fluids
Hydration shell
60
contains proteoglycan
aggregates and several specific
multiadhesive glycoproteins,
including osteonectin
Organic matter
61
Organic matter embedded in the calcified matrix is
–
Type I collagen
–
ground substance
62
Calcium binding glycoproteins example
osteocalcin, and the phosphatases
released in matrix vesicles by osteoblasts
63
PERIOSTEUM ENDOSTEUM Principle Function
Provide nutrition of osseus
Provision of a continuous supply of new osteoblasts for repair or growth of bone
64
consists of a dense fibrous outer layer of
collagen bundles and fibroblasts
attaches to bone tissue through perforating
fibers
Periosteum
65
bundles of periosteal collagen fibers that
penetrate the bone matrix, binding the
periosteum to bone
Perforating or Sharpey's fibers
66
mesenchymal stem cells found in the
innermost cellular layer of the periosteum
–
has potential to divide by mitosis and
differentiate into osteoblasts
–
play a prominent role in bone growth
and repair
Osteoprogenitor cells
67
provides covering to inner layer of bones
a single very thin layer of connective tissue,
containing flattened osteoprogenitor cells
and osteoblasts
Endosteum
68
–
covers the small spicules or
trabeculae of bone that project into
these cavities
–
considerably thinner than the
periosteum.
–
lines the large internal marrow
cavities of bone
Endosteum
69
TYPES OF BONE
Compact Bone
Cancellous (spongy) Bone
Long Bone
Short Bones
Flat Bones
70
areas with numerous interconnecting cavities
all surfaces of ________ are covered with endosteum
cancellous bone
71
bulbous end of long bones composed of spongy bone covered with a thin layer of compact bone
Epiphyses
72
Long Bone
* Has two components:
Epiphyses
Diaphysis
73
cylindrical part is almost totally composed of compact bone, with a thin component of spongy bone on its inner surface around the bone marrow cavity
Diaphysis
74
usually have a core of spongy bone surrounded completely by compact bone
Short Bones
75
calvaria (skullcap) have two layers of compact bone called
plates (tables)
76
the plates of the calvaria are separated by a thicker layer of spongy bone called the
diploë
77
* first bone tissue to appear in embryonic development and in fracture repair
* immature bone
PRIMARY BONE TISSUE
78
PRIMARY BONE TISSUE characterized by irregular array of collagen fibers called
woven bone
79
PRIMARY BONE TISSUE are usually temporary, except in:
o near the sutures of the calvaria
o in tooth sockets
o in the insertion of some tendons
80
SECONDARY BONE TISSUE
* shows multiple layers of organized calcified matrix referred to as
lamellar bone
81
each complex of concentric bony lamellae surrounding a small canal containing blood vessels, nerves, and loose connective tissue
Osteon (Haversian system)
82
* outer boundary of each osteon is a more collagen-rich layer which we call as?
Cement line
83
CATEGORIES OF VASCULAR CHANNELS
Haversian canals
Volkmann’s Canals
84
* longitudinal channels in the centers of the haversian systems/ osteons containing one or two blood vessels
* parallel
* connected with one another and communicate with the free surface and marrow cavity through transverse and oblique channels called Volkmann’s Canals
Haversian canals
85
* are not surrounded by concentrically arranged lamellae but traverse the bone in a direction perpendicular or oblique to the lamellae
* larger than the haversian canals
* traversing the bone
Volkmann’s Canals
86
* Bone formation
* Has two process : in both processes, the bone tissue that appears first is primary or woven
OSTEOGENESIS
87
two process of OSTEOGENESIS
Intramembranous ossification
Endochondral ossification
88
in which osteoblasts differentiate directly from mesenchyme and begin secreting osteoid
Intramembranous ossification
89
in which the matrix of preexisting hyaline cartilage is eroded and replaced by osteoblasts producing osteoid
Endochondral ossification
90
Vitamin D Deficiency diseases
Rickets
Osteomalacia (adults)
91
* results from faulty absorption of calcium form foods and a diminished phosphate concentration in plasma
* epiphyseal discs become thicker and irregular, and the cartilage matrix and osteoid tissue fail to calcify
Rickets
92
* causes a diminution in calcium content of the bone
Osteomalacia (adults)
93
inability of tissues that originate from mesenchyme to produce and maintain fibers, and ground substance diminished
* causes destruction of osteocollagenous fibers and a production of organic matrix in bones
* deficiency may lead to growth retardation and delayed healing of fractures
Vitamin C Deficiency
94
diminution in the rate of skeletal growth and interference with the process of remodeling together with the balance between bone deposition and erosion
Vitamin A Deficiency
95
HORMONES INFLUENCING GROWTH AND MAINTENANCE OF BONES
Parathyroid hormone
Calcitonin
Growth Hormone
Sex Hormones
96
* regulates bone resorption controlling the release of calcium to the blood
* regulates hypocalcemia
* acts upon the kidney to increase the rate of resorption calcium from the glomerular filtrate
* its renal effect prevents a continual loss of calcium in the urine that would ultimately deplete the calcium stores in the bones
Parathyroid hormone
97
* inhibits resorption activity
* oppose the function of PTH
Calcitonin
98
Calcitonin * a thyroid hormone, excreted by the
parafollicular C cells of the thyroid gland
99
Calcitonin exerts its calcium lowering effect by inhibiting the actions of both
PTH and vitamin D
100
Calcitonin secreted in response to a
hypercalcemic stimulus
101
Growth Hormone Produced by the
anterior pituitary
102
GH deficiency and excessive production leads to?
lack (dwarfism),
excessive production (gigantism)
103
decline in this hormone secretion disturbs the balance between bone deposition and bone resorption resulting in fragile bones (aging)
Sex Hormones
104
this hormone affects the appearance and closure of the secondary or epiphyseal ossification centers
* skeletal maturation is accelerated and growth stunted (precocious puberty)
Sex Hormones
105
BONE REPAIR process
1) Fracture →
2) hemorrhage (from torn vessels) and clotting →
3) fibroblasts and capillaries invades the clot forming granulation tissue (procallus) →
4) transforms to dense fibrous tissue and later into cartilage (temporary callus) →
5) Bone is remodelled
106
JOINTS Classification
Diarthroses
Synarthroses
107
* permit free bone movement
* joints that generally unite long bones and have great mobility, such as elbow and knee joints
Diarthroses
108
* very limited or no movement occurs
* example : skull
Synarthroses
109
Components of Diarthroses:
Capsule
Synovial or joint cavity
Articular cartilage
110
continuous with a covering ligament which inserts into the periosteum of both bones
Capsule
111
lined by synovial membrane and containing synovial fluid as a lubricant
Synovial or joint cavity
112
covers the ends of epiphyses
Articular cartilage
113
colorless, transparent, viscous fluid
o derived from blood plasma, but with a high concentration of hyaluronic acid produced by cells of the synovial membrane
Synovial Fluid
114
* specialized connective tissue that lines the joint cavity
o
which extends folds and villi into
the cavity and secretes the
lubricant synovial fluid.
Synovial Membrane
115
Three Types Of Synarthroses
(Based On The Type Of Tissue Uniting The
Bone Surfaces):
Synostoses
Synchondroses
Syndesmoses
116
o
bones are united by bone tissue
and no movement takes place
o
in older adults, __________ unite
the skull bones
synostoses
117
o
bones are joined by hyaline
cartilage
o
epiphyseal plates of growing
bones
o
in adults a _____ unites
the first rib to the sternum with
little movement
synchondroses
118
o
bones are joined by an
interosseous ligament of dense
connective tissue or fibrocartilage
o
pubic symphysis
Syndesmoses
