Bone Histology (quiz 4) Flashcards
1
Q
Cartilage is resilient, semirigid form of connective tissue that forms parts of the skeleton where more ___________ is required
A
flexibility
2
Q
What does costal cartilage attach?
A
ribs to sternum (with hyaline cartilage)
3
Q
Articular cartilage covers the articulating surfaces (_______________ surfaces) that are part of synovial joints. It provides smooth, low-friction gliding surfaces for free movement.
A
weight bearing
4
Q
Is cartilage vascular or avascular?
A
avascular
blood vessels do not enter cartilage, so its cells obtain oxygen and nutrients by diffusion
5
Q
The portion of bone and cartilage in the skeleton changes as the body ages and grows. How?
A
younger= more cartilage
bones of a newborn are soft and flexible because they are mostly composed of cartilage
6
Q
What are the 3 types of cartilage?
A
1) hyaline cartilage (most common)
2) fibrocartilage (2nd most abundant, found in pubic symphysis and IVD)
3) elastic cartilage (found in the nose and ears for mobility)
7
Q
Periosteum simply means….
A
around the bone
8
Q
Bones are a highly specialized living tissue. Bones are the hard form of connective tissue that makes up most of the skeleton. Each bone is surrounded by fibrous connective tissue called…..
A
periosteum
9
Q
What nourishes the external aspects of skeletal tissue?
A
periosteum
10
Q
What is capable of laying down more bone in healing fractures and growth?
A
periosteum
11
Q
What provides the interface for attachment of tendons and ligaments?
A
periosteum
12
Q
What carries the nerve receptors for pain?
A
periosteum
(this is a protective function for bones to try to prevent damage)
13
Q
Adult bones provide support for the body and its vital cavities. Bones are the primary supporting tissue of the body. Bones protect vital organs and structures. Bones are the mechanical basis for movement (leverage) with joints and muscle attachments. Bones store salts, particularly __________ for homeostasis. Bones produce new blood cells for hematopoiesis in ______ bone marrow. Bones also store triglycerides (fats) in ________ bone marrow
A
calcium, red, yellow
14
Q
What tissue contains abundant intercellular matrix, with widely dispersed cells and is avascular?
A
connective tissue
15
Q
Which cartilage has very fine collagen fibers that appear glassy?
A
hyaline cartilage
16
Q
Which cartilage is found at the epiphyseal growth plate?
A
hyaline cartilage
17
Q
What cartilage is articular cartilage?
A
hyaline cartilage
18
Q
Which cartilage has large amounts of collagen?
A
fibrocartilage
19
Q
Which cartilage is not found in bones, but is present in joints?
A
fibrocartilage
20
Q
What cartilage forms annulus fibrosus of IVD?
A
fibrocartilage
21
Q
What cartilage is a characteristic of symphyses?
A
fibrocartilage
22
Q
What cartilage contains large amounts of elastin and is found in small quantities in the skeleton?
A
elastic cartilage
23
Q
What are the 3 properties of bone tissue?
A
1) hardness (inorganic)
2) flexibility (organic)
3) tensile strength (organic)
24
Q
Osseous tissue has a matrix that is made up of 5-10% of water, organic phase which is 30-35% collagen fibers, and mineral phase which is 60% of crystalized mineral salts. The mineral salts are composed of hydroxyapatite (___________________________) and magnesium hydroxide, fluoride, and sulfate
A
calcium carbonate and calcium phosphate
25
The matrix of osseous tissue undergoes calcification which is where mineral salts make the collagen fiber matrix harden and crystalize. What is this initiated by?
osteoblasts
26
There are 2 types of bone tissue- woven and lamellar bone. What is the difference?
Woven bone has a haphazard layout of collagen fibers and is considered immature bone. It is seen in ossification centers and bony calluses
Lamellar bone is highly organized collagen fibers that is considered mature bone. It is seen in compact and spongy bone
27
What is another name for compact bone?
cortical bone
28
What type of bone forms the outside of all bone and bulk of the bone shaft?
compact bone
29
What type of bone provides protection and support, resists stresses of weight and movement?
compact bone
30
Which type of bone is found in high direct stress areas?
compact bone
31
Which type of bone bends and has torsion, and is less elastic?
compact bone
32
Which type of bone uses the osteon organizational system (Haversian system)
compact bone
33
What brings vessels to individual osteons and runs longitudinally?
central (Haversian) canals of the osteon
34
What are the 3 types of lamellae?
1) concentric
2) interstitial
3) circumferential
35
What lamellae is found on the rings of calcified matrix around the central canal?
concentric lamellae
36
What lamellae is found between osteons (fills in gaps)?
interstitial lamellae
37
What lamellae is found on the surface of bone?
circumferential lamellae
38
What are the 2 types of circumferential lamellae?
1) outer circumferential (on the outer surface of bone)
2) inner circumferential (on the inner surface of bone)
39
What brings vessels, nerves, and lymphatics from periosteal supply and runs transversely?
perforating (Volkmann's) canals
40
What are the small spaces between lamellae called?
lacunae ("little lakes")
40
Where do osteocytes usually hang out?
inside lacunae
41
What are the connections between lacunae called?
canaliculi ("little canals")
42
What is filled with ECF and osteocyte projections, and provides communication between osteocytes via gap junctions and connection to vessels in canals?
canaliculi
43
What is another name for spongy bone?
cancellous or trabecular bone
44
What is the primary component of short, flat, and irregular bones, found in the lower direct stress areas (compression forces at epiphyses, bony protection with less weight, like the skull, and easier to move)?
spongy bone
45
What type of bone uses trabeculae instead of osteons?
spongy bone
46
What part of spongy bone provides space and protection for red and yellow bone marrow, and is the only site of hematopoiesis in adults (ribs, sternum, vertebral bodies, proximal epiphyses of femur and humerus, ala of ilium)?
trabeculae
47
What type of bone has an irregular framework? What does it consist of?
spongy bone
-interstitial lamellae
-lacunae w/ osteocytes
-canaliculi w/ osteocyte projections and communication between osteocytes via gap junctions and with vessels of red BM
-osteoblasts and osteoclasts found on surface
48
What is another name for osteoprogenitor cells?
osteogenic cells
49
What cells are found in the periosteum, endosteum, and vascular canals?
osteoprogenitor cells (osteogenic cells)
50
What is the bone stem cell?
osteoprogenitor cells (osteogenic cells)
51
What cells are derived from mesenchyme (embryonic CT)?
osteoprogenitor cells (osteogenic cells)
52
Which cells are mitotically active and differentiate into osteoblasts?
osteoprogenitor cells (osteogenic cells)
53
What are the bone-building cells?
osteoblasts
54
What are the 2 basic jobs of osteoblasts?
1) synthesize and secrete collagen and other organic materials
2) initiate calcification
55
Name this cell-
When they become trapped in their own matrix, they differentiate into osteocytes
osteoblasts
56
Which bone cells cannot undergo mitosis?
osteoblasts
57
What are the mature bone cells called?
osteocytes
58
What is the primary bone cell in bone tissue?
osteocytes
59
What cells maintain daily metabolism of bone?
osteocytes
60
What bone cells are the largest? Why are they the largest?
osteoclasts, made from fusion of many monocytes (WBCs)
61
What bone cells are concentrated in the endosteum?
osteoclasts
62
What bone cells are multinucleated due to the fusion of many cells?
osteoclasts
63
What bone cell releases powerful lysosomal enzymes and acids?
osteoclasts
64
What bone cell is in charge of resorption of the bone matrix through development and growth, and maintenance and repair?
osteoclasts
65
Bone is a major reservoir for __________
calcium (99% of total body calcium found in bone)
66
Calcium is needed for what?
-nerve impulses
-enzyme activity
-blood clotting formation (hemostasis)
-buffers
-muscle contraction
67
Blood levels of calcium is regulated by _____________ and ________________ of calcium in the bone. This is regulated by hormones
deposition, resorption
68
What hormone is stimulated by high blood calcium levels?
calcitonin (CT)
69
What hormone decreases blood calcium levels?
Calcitonin (CT)
70
Calcitonin decreases blood calcium levels. What does this do?
-inhibits osteoclast activity
-activates osteoblasts (promotes bone formation, removes calcium from blood)
71
What hormone is stimulated by low blood calcium levels?
parathyroid hormone (PTH)
72
What hormone increases blood calcium levels?
parathyroid hormone (PTH)
73
Parathyroid hormone (PTH) increases blood calcium levels. What are the steps here?
1) inhibit osteoblasts and activate osteoclasts (returns calcium to blood)
2) decreases loss of calcium through kidneys (keeps calcium in blood)
3) stimulates formation of calcitriol (vitamin D, increases calcium absorption in GI and adds new calcium to the blood)
Note: calcitonin (CT) and parathyroid hormone (PTH) are opposites of each other
74
There are 2 kinds of CT in the embryonic skeleton. What are they?
fibrous CT membranes and pieces of hyaline cartilage
75
When does ossification of CT in embryonic skeletons begin?
week 6-7 of development
76
How are both of the ossification processes similar?
-both form spongy bone and compact bone (mature bone tissues)
-both begin with "woven bone" (also the start of fracture healing, this is immature bone tissue)
77
What is embryonic CT called?
mesenchyme (a diffuse network of cells forming embryonic mesoderm)
78
All CT develop from....
mesenchyme
79
Bone anlagen initially form as....
mesenchymal condensations (these will undergo direct intramembranous or indirect endochondral ossification)
80
Mesenchymal cells can differentiate into other cell types:
-fibroblasts
-chondroblasts
-osteoblasts
-myoblasts
81
Mesenchyme in the head region is derived from __________________________________. These give rise to cranial bone of the ________________________
neuroectoderm (neural crest cells), pharyngeal arch origin
82
Which type of ossification forms bones directly on or within loose fibrous CT membranes and forms neurocranial bones (calvaria)?
intramembranous ossification
83
What are the 4 basic steps of intramembranous ossification?
1) development of ossification center
2) calcification of the membrane
3) formation of trabeculae
4) development of periosteum
84
What happens in step 1 of intramembranous ossification?
development of the ossification center
-mesenchymal cells cluster and differentiate into osteogenic cells and then osteoblasts
-osteoblasts secrete bony matrix and are surrounded by it (this is called an osteoid)
85
What happens in step 2 of intramembranous ossification?
calcification
-matrix secretion stops and the matrix hardens
-cells are called osteocytes now
-lacunae and canaliculi are formed
86
What happens in step 3 of intramembranous ossification?
formation of trabeculae
-trabeculae fuse together to form cancellous bones
-blood vessels grow into spaces
-RBM formed by the end of this step
87
What happens in step 4 intramembranous ossification?
development of the periosteum
-mesenchyme at the periphery condenses into periosteum
-thin layers of cortical bone replace surface layers of spongy bone
-remodeling takes the bone to adult shape and size
88
Which ossification method is more complex? Why?
endochondral ossification
-cartilage model (anlagen) forms within loose fibrous CT membranes
-bone then forms from the cartilage anlagen
89
Which ossification method forms long, short, and irregular bones?
endochondral ossification
90
What are the 5 basic steps of endochondral ossification?
1) development of cartilage anlagen
2) growth model of anlagen
3) development of primary ossification center
4) development of secondary ossification center
5) formation of articular cartilage and epiphyseal plate
91
What are the 4 main parts of a long bone?
-covered by periosteum
-diaphysis (body of long bone)
-epiphysis (2 ends- proximal and distal)
-metaphysis
92
What is found within the diaphysis (body of long bone)?
-medullary cavity (YBM stores fat/triglycerides)
-endosteum
93
What is found within the epiphysis of long bone?
-articular cartilage on both proximal and distal end (hyaline cartilage)
-RBM on proximal end only
94
What is found within the metaphysis of long bone?
epiphyseal plate/line
plate is while child is growing
line is when child turns into an adult and stops growing in length, usually by age 18
95
RBM is a highly vascularized CT located in the microscopic spaces between the _______________ of cancellous bone tissue
trabeculae
96
In adults, RBM is present chiefly in the bones of the ________ skeleton, ______________________, and the proximal epiphyses of the humerus and femur
axial, pectoral and pelvic girdles
97
RBM is derived from ____________________ which can develop into several different types of cells. These come from mesenchymal cells
hemocytoblasts
note: as you get older you need/have less blood
98
In newborns, RBM is red and active in blood cell production. Blood cell production decreases with age. The inactive RBM becomes....
YBM (predominantly fat cells)
note: under certain conditions, such as severe bleeding, YBM can revert to RBM by extension of RBM into YBM and repopulation of YBM by pluripotent stem cells (hemocytoblasts)
99
T/F: bone has an abundant blood supply
true
100
Areas of RBM get the most _________________ supply, as opposed to other areas of bone
blood, lymph, and nerve
101
What is the blood supply of long bones?
Think arteries and veins!
-periosteal aa. + vv.
-nutrient a. + vv.
-metaphyseal aa. + vv.
-epiphyseal aa. + vv.
-anastomoses
102
What is the lymph and nerve supply of long bones?
Think: where are lymphatic vessels and nerves coming from?
lymphatic vessels follow perforating aa. and vv.
nerves follow all vessels that supply bone (periosteum is rich in sensory nerves and helps with feeling tearing, tension, and pain for the bone)
103
What is step 1 of endochondral ossification?
development of the cartilage model (anlagen)
-mesenchymal cells crowd together in shape of future bone
-mesenchymal cells differentiate into chondroblasts
-chondroblasts secrete cartilage matrix to produce hyaline cartilage model covered by perichondrium
note: perichondrium is on the surface of cartilage, whereas periosteum is on the surface of bone
104
What is step 2 of endochondral ossification?
growth of the cartilage model
-chondrocytes go through continual mitosis causing the model to grow (growth in length and width)
-chondrocytes in mid-region hypertrophy (some burst which increases pH and triggers calcification, while others die within matrix and forms lacunae)
growth in length = interstitial growth (addition of cells)
growth in width = appositional growth (deposition of matrix)
105
What is interstitial growth?
growth in length (addition of cells)
106
What is appositional growth?
growth in width (deposition of the matrix)
107
What is step 3 of endochondral ossification?
this one is lonnnnnnnggggg
development of the primary ossification center
-from external to internal
-nutrient a. penetrates perichondrium and cartilage model
-creates a nutrient foramen approx. mid-shaft
-stimulates osteogenic cells in perichondrium to make osteoblasts
-osteoblasts secrete the periosteal bone collar (thin shell of compact bone deep to the perichondrium)
-perichondrium become periosteum
-periosteal capillaries grow in the disintegrating calcified cartilage
-capillaries induce growth of primary ossification center (where bone will first replace most of the cartilage)
-osteoblasts deposit bone matrix over the calcified cartilage remnants (forms spongy trabeculae)
-ossification center grows towards epiphysi (osteoblasts break down parts of newly formed trabeculae creating medullary cavity and the medullary cavity fills with RBM)
108
What is step 4 of endochondral ossification?
development of secondary ossification centers
-branches of the epiphyseal aa. enter the epiphyses
-creates secondary center of ossification (this usually begin around the time of birth)
-process the same as primary ossification center EXCEPT no medullary cavity is formed and it proceeds from the center of the epiphysis to outside of the bone
109
What is step 5 of endochondral ossification?
formation of articular cartilage and epiphyseal plate
-cartilage covering epiphysis becomes articular cartilage
-hyaline cartilage remains between each diaphysis and epiphysis
>>epiphyseal plate is the growth plate, when the plate ossifies, then the growth in length stops and is called the epiphyseal line
110
What are the 2 ways bones grow?
interstitial and appositional growth
interstitial growth is growth in length, mostly known for epiphyseal plate (layer of hyaline cartilage in the metaphysis of growing bone)
appositional growth is also known as deposition, where it grows bones in width, thickness, and diameter
111
What are the 4 zones of interstitial growth (growth in length)?
1) zone of resting cartilage
2) zone of proliferating cartilage
3) zone of hypertrophic cartilage
4) zone of calcified cartilage
112
What is the zone of resting cartilage in interstitial growth?
-nearest epiphysis
-small scattered chondrocytes
-anchors epiphyseal plate to bone in epiphysis
113
What is the zone of proliferating cartilage in interstitial growth?
-larger chondrocytes than in the zone of resting cartilage, and are arranged in stacks like coins
-highly mitotic to replace chondrocytes dying at the diaphyseal end
114
What is the zone of hypertrophic cartilage in interstitial growth?
-even larger chondrocytes than in the zone of resting cartilage or zone of proliferating cartilage, and are arranged in columns
-maturing chondrocytes
115
What is the zone of calcified cartilage in interstitial growth?
-few cells thick
-mostly dead chondrocytes from calcifying matrix
-osteoclasts dissolve cartilage
-osteoblasts and capillaries invade and lay down bony matrix
-epiphyseal plate firmly "cemented" to bone of diaphysis
116
Summarize interstitial growth
-new chondrocytes replace old ones
-old ones are destroyed by calcification
-cartilage is replaced by bone on the diaphyseal side of the plate
-for most of the process, the epiphyseal plate remains constant in size, but diaphysis lengthens, and the epiphysis grows
-growth stops when chondrocytes cease mitosis and are replaced completely by bone
>> presence of epiphyseal line means growth has stopped
>> damage to growth/epiphyseal plate can cause premature cessation of growth in length for that bone
117
The ___________ is the first bone to start ossification and the last one to stop (at 33 y/o)
clavicle
118
Most long bones complete ossification between _____ years old
14-19
119
What are the 4 steps of appositional growth?
1) osteoblasts form ridges around periosteal aa. (secretion of the matrix, differentiation into osteocytes, and build up of outer circumferential lamellae)
2) The ridges build and fuse together (encircles artery and the separated periosteum becomes endosteum of canal around artery)
3) osteoblasts build more layers (lamellae) to fill in space around the vessels to form osteons
4) osteoblasts produce circumferential lamellae to further thicken bone
remember that osteoclasts are dissolving bone in the medullary cavity (this enlarges medullary cavity as shaft grows outward and maintains portions and increasing marrow needs, such as yellow BM with triglyceride storage)
120
What is the average fracture healing time?
2-3 months, but can be longer for people taking NSAIDs, have osteoporosis, etc
121
What is the 1st step to healing fractures?
formation of fracture hematoma
-clot forms around site of fracture (fracture hematoma)
-circulation stops at the site of injury and nearby bone cells die
-swelling and inflammation occurs producing more debris
-capillaries grow and bring in osteoclasts and phagocytes
122
What is the 2nd step to healing fractures?
fibrocartilaginous callus formation
-procallus (hard as cement, actively growing CT)
-fibroblasts invade procallus (produce collagen to glue it all together
-cleanup continuous
-procallus becomes fibrocartilaginous callus (stronger)
123
What is the 3rd step of healing fractures?
bony callus formation
-osteogenic cells differentiate into osteoblasts
-production of trabeculae to join living tissue to dead tissue
-fibrocartilage becomes spongy bone = bony callus (initially woven bone, will become mature bone)
124
What is the 4th step of healing fractures?
bone remodeling
-dead portions of bone reabsorbed
-compact bone replaces spongy bone at periphery and where previously found in callus
-callus smoothed out, often barely detectable
125
Are types of fractures used in combination?
yes sometimes
126
What is an open/compound fracture?
open fracture that perforates the skin, this fracture takes the longest to heal
127
What is a closed/simple fracture?
fracture is closed, has NOT pierced the skin (usually a small fracture)
128
What is a complete fracture?
bone is broken into 2+ separate pieces
129
What is an incomplete/partial fracture?
the bone is only cracked or partially broken (did not fully break)
130
What are the directional plane types of fractures?
-transverse (bone is broken perpendicular to its length)
-oblique (bone is broken at an angle/diagonal)
-spiral (broken with a twisting motion, looks like corkscrew)
longitudinal (stress, broken along the axis of bone)
131
What is a common fracture found in ribs, usually in children during child abuse (at the angle of the rib posteriorly)?
spiral fracture
132
What is a comminuted fracture?
broken into many pieces, 3+
133
What is a greenstick fracture?
bone cracks on one side only, not all the way through the bone (common in children)
134
What is an impacted fracture?
the broken ends of the bone are jammed together by the force of the injury
135
What is a distracted/displaced fracture?
the pieces of the bone moved so much that a gap formed around the fracture
136
What is an overlapped fracture?
displaced fracture where the bone fragments overlap
137
What is an angulated fracture?
fracture displacement where the normal axis of the bone has been altered such that the distal portion of the bone points off in a different direction
138
What is a rotated fracture?
fracture displacement where the rotation of the distal fracture fragment has been moved in relation to the proximal portion
this is common in the elderly and it heals slowly
139
What is a shifted fracture?
bone breaks into two or more pieces and moves out of alignment
140
What is a depressed fracture?
fracture of the skull where it depresses below the normal surface (can develop subdural hematoma)
141
What is a potts fracture?
ankle fracture, characterized by a break in the lateral malleolus
142
What is a colles fracture?
break in the radius close to the wrist (common in children and elderly)
143
Bone remodeling is for growth, repair, and response to stress. It is the balance of...
osteoblasts and osteoclasts
144
What happens if theres too much osteoblast activity?
abnormally thick and heavy bone (arthritic lipping and calcium spurs)
note: its the opposite for osteoclasts, so too little osteoclasts= abnormally thick and heavy bone
145
What happens if theres too little osteoblast activity?
weakened bone tissue
note: its the opposite for osteoclasts, so too much osteoclasts = weakened bone tissue
146
What are the dietary needs that affect bone growth and healing?
-calcium and phosphorus in large amounts (small amounts of F, Mg, Fe, and Mn)
-Vitamin C (needed for collagen synthesis and differentiation of osteoblasts into osteocytes)
-vitamin K and B (needed for protein synthesis)
-vitamin A (retinol, retinoic acid, stimulates activity of osteoblasts)
-vitamin D3 (cholecalciferol)
147
What vitamins are needed in large amounts in our diet for bone growth and healing?
calcium and phosphorus
148
What vitamin is needed for collagen synthesis and helps with differentiation of osteoblasts into osteocytes?
vitamin C
149
What vitamins are needed for protein synthesis?
vitamin K and B
150
What vitamin stimulates activity of osteoblasts?
vitamin A/retinol/retinoic acid
151
What hormones are needed for bone growth and healing?
-human growth hormone (hGH, produced by the anterior pituitary and stimulates IGFs (insulin like growth factor))
-insulin like growth factor (IGFs, produced by bones and liver, promote cell division and enhance synthesis of proteins needed for growth)
-sex steroids (estrogen and androgens)
152
Which hormone is produced by the anterior pituitary and stimulates insulin-like growth factors (IGFs)?
human growth hormone (hGH)
153
What hormone is produced by bones and the liver and promotes cell division and enhances synthesis of proteins needed for growth?
insulin-like growth factors (IGFs)
154
What sex steroids affect bone growth and healing?
estrogen and androgens
155
What do sex steroids do for bone growth and healing?
secondary skeletal sexual characteristics caused by sex hormones
sex steroids increase osteoblast activity and synthesis of matrix (growth spurt during puberty)
-high levels of estrogen begin growth spurt
-higher levels of estrogen stop growth spurt and growth in height)
-this is relative to levels of testosterone
