What fibers are embedded in chondroitin sulfate in the cartilage matrix?
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Elastic fibers.
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What fibers are embedded in chondroitin sulfate in the cartilage matrix?
Elastic fibers.
Which types of cartilage are present in the external ear, intervertebral discs, pubic symphysis, and epiglottis?
External ear: Elastic cartilage, Intervertebral discs: Fibrocartilage, Pubic symphysis: Fibrocartilage, Epiglottis: Elastic cartilage
Which of the following is NOT a glycosaminoglycan in cartilage?
B. Proteoglycans
What are some examples of glycosaminoglycans found in cartilage?
Chondroitin sulfate, Keratan sulfate, and Hyaluronic acid
What are the main components of the matrices surrounding chondrocytes in elastic cartilage?
Type II collagen, proteoglycans, and elastic fibers.
What type of tissue is shown in the images provided?
Cartilage tissue.
What type of cartilage is surrounded by the perichondrium?
Hyaline cartilage.
What is a distinguishing characteristic of fibrocartilage under a microscope?
The presence of dense collagen fibers.
What is the perichondrium, and what is its role in cartilage?
The perichondrium is a dense layer of connective tissue that surrounds cartilage, providing nutrients and growth factors essential for cartilage growth and repair.
What forms a proteoglycan monomer in the cartilage matrix?
Chondroitin sulfate and keratan sulfate joined to a core protein.
Which type of cartilage contains elastic fibers in its extracellular matrix?
Elastic cartilage.
What happens above the tidemark in cartilage?
Proliferation of chondrocytes within the cartilage lacunae provides new cells for interstitial growth.
Do hyaline cartilage of articular joint surfaces possess a perichondrium?
No.
What are the distinguishing features of elastic cartilage?
Elastic cartilage contains a dense network of elastic fibers that provide flexibility and resilience.
Where in the body is hyaline cartilage commonly found?
Hyaline cartilage is commonly found in the nose, trachea, larynx, ends of long bones, and the fetal skeleton.
What is the territorial matrix in cartilage?
The territorial matrix is the area of the cartilage matrix that surrounds individual chondrocytes or groups of chondrocytes, providing structural support and protection.
What type of cells are indicated by the label 'C' in the histological images?
The label 'C' indicates chondrocytes, the cells found in cartilage.
What are the primary components of intervertebral discs composed of?
Primarily of fibrocartilage.
What does the dense matrix surrounding the cells in cartilage tissue primarily consist of?
Collagen fibers and proteoglycans.
Where does hyaline cartilage occur?
In the temporary skeleton of the embryo, articular cartilage (ends of long bones, ends of ribs), and cartilage of the respiratory tract (nose, parts of larynx, trachea, bronchi, bronchial tubes).
Where in the body is fibrocartilage commonly found?
In areas such as intervertebral discs, pubic symphysis, and menisci of the knee.
How do chondroblasts contribute to appositional growth?
Chondroblasts, derived from chondrogenic cells in the perichondrium, begin to elaborate matrix and contribute to the growth at the surface of the cartilage.
What is the function of chondrocytes in cartilage?
Chondrocytes are cells responsible for the synthesis and maintenance of the cartilage matrix.
What is the primary function of chondrocytes?
Chondrocytes are specialized cells that produce and maintain the extracellular matrix.
What is found in the territorial matrix surrounding chondrocytes?
The territorial matrix consists of randomly arranged type II collagen fibrils surrounded by proteoglycans.
What is the main characteristic of hyaline cartilage as shown in the image?
It has an extracellular matrix with lacunae containing chondrocytes.
What types of collagen fibrils are present in the cartilage matrix?
Type II collagen fibrils.
In articular cartilage renewal, where do chondrocytes migrate from and to?
Chondrocytes migrate from the region above the tidemark toward the joint surface.
What are the features of the deep (radial) zone in cartilage?
It is characterized by small, round chondrocytes arranged in short columns perpendicular to the surface, with collagen fibrils positioned parallel to the long axis of the bone.
Where in the human body can elastic cartilage be commonly found?
Elastic cartilage can be found in the external ear, epiglottis, and the Eustachian tube.
What are the main components of hyaline cartilage?
The main components of hyaline cartilage are chondrocytes, collagen fibers (primarily Type II), and a gel-like ground substance.
Where is hyaline cartilage located in adults?
In the articular surfaces of movable joints, in the walls of larger respiratory passages (nose, larynx, trachea, bronchi), in the ventral ends of ribs, where they articulate with the sternum, and in the epiphyseal plates of long bones.
What role does hyaline cartilage play in the epiphyseal plates of long bones?
It makes possible longitudinal bone growth.
What are the three types of cartilage?
Hyaline cartilage, Elastic cartilage, and Fibrous cartilage.
What two major components make up each intervertebral disc?
The peripheral annulus fibrosus rich in bundles of type I collagen and the central nucleus pulposus with a gel-like matrix.
What distinguishes the intermediate (transitional) zone of cartilage?
It contains round chondrocytes randomly distributed within the matrix, with less organized collagen fibrils.
What does the matrix of hyaline cartilage contain?
Type II collagen interacting with proteoglycans.
What is the characteristic feature of the calcified zone (CZ) in articular cartilage?
The calcified zone exhibits a calcified matrix, lacks chondrocytes, and is lighter staining than the matrix of more superficial zones.
What results from the multiplication of chondroblasts within the matrix?
Isogenous cell aggregates.
What is the primary function of the perichondrium in cartilage?
The perichondrium provides nutrients to the cartilage and supports growth and repair.
Where can elastic cartilage be found in the body?
In the external ear, epiglottis, and auditory tubes.
Why does the extracellular matrix of hyaline cartilage act as a shock absorber?
Because of its stiffness and elasticity.
What is the origin of articular cartilage in adults?
Articular cartilage is a remnant of the original hyaline cartilage template of the developing bone.
How thick is the articular cartilage in adults and how is it divided?
The articular cartilage is 2 to 5 mm thick and is divided into four zones.
What type of cartilage lacks a perichondrium?
Fibrocartilage
What is interstitial growth in cartilage?
It is a growth process where cartilage expands from within, during which mesenchymal cells aggregate, differentiate into chondroblasts, and form centers of chondrogenesis.
What is an isogenous group?
An isogenous group is formed when daughter cells remain within the same space or lacuna after division, surrounded by territorial matrix.
What is appositional growth in cartilage?
Growth from undifferentiated cells at the surface of the cartilage or perichondrium, where chondrogenic cells in the inner cellular layer of the perichondrium divide and differentiate into chondroblasts, which begin to elaborate matrix.
What provides resilience to the cartilage matrix?
Chondroitin sulfate.
What type of tissue is cartilage?
Cartilage is a specialized form of connective tissue.
What is the function of hyaline cartilage in embryos?
Hyaline cartilage forms the temporary skeleton that is gradually replaced by bone.
Which type of cartilage is known for its flexibility and is found in the ear?
Elastic cartilage.
What types of cartilage are shown in the image?
Hyaline cartilage, fibrocartilage, and elastic cartilage.
What is elastic cartilage surrounded by?
Perichondrium.
What is the role of hyaluronic acid in the cartilage matrix?
Hyaluronic acid binds to proteoglycans and forms aggregates, contributing to the tensile strength and elasticity of the cartilage.
What are the two main types of cells visible in cartilage tissue?
Chondrocytes and chondroblasts.
What is the main function of hyaline cartilage?
Resists compression, provides cushioning, smooth and low-friction surface for joints. It also provides structural support in the respiratory system and serves as a foundation for fetal skeleton development and endochondral bone formation.
Which type of cartilage undergoes calcification and in what circumstances?
Hyaline cartilage undergoes calcification during endochondral bone formation and aging, while fibrocartilage undergoes calcification during bone repair.
What cells are found in fibrocartilage?
Chondrocytes and fibroblasts
Why can cartilage endure a great deal of stress?
Cartilage is capable of enduring a great deal of stress because of its specialized structure and the presence of chondrocytes embedded in extensive ECM.
Which of the following contains hyaline cartilage?
Trachea
Which type of cartilage is the most abundant and provides support with some flexibility?
Hyaline cartilage.
What are the labels 'P' and 'M' indicating in the histological images?
The labels 'P' and 'M' typically represent perichondrium and matrix, respectively.
Where is elastic cartilage found?
In the auricle of the ear, walls of the external auditory canals, auditory (eustachian) tubes, epiglottis, and cuneiform cartilage in the larynx.
What are the two roles of the specialized extracellular matrix of hyaline cartilage in joints?
What type of cartilage is shown in the image?
Elastic cartilage.
What type of cartilage is shown in the image?
Fibrocartilage.
What does the lacunar rim consist of?
The lacunar rim is the inner layer of the territorial matrix and consists of loose collagen fibrils.
What are the three kinds of glycosaminoglycans found in the ground substance of hyaline cartilage?
Hyaluronan, chondroitin sulfate, and keratan sulfate.
What is the role of glycosaminoglycans in cartilage?
Glycosaminoglycans are important components of the cartilage matrix, contributing to its resilience and ability to withstand compressive forces.
Which cells are found in the perichondrium of cartilage?
Perichondrial fibroblasts and chondroblasts.
What are the four zones of articular cartilage shown in the diagram?
Superficial (tangential) zone, intermediate (transitional) zone, deep (radial) zone, and calcified zone.
Which types of cartilage have the presence of the perichondrium?
Hyaline cartilage (except articular cartilage and epiphyseal plates) and elastic cartilage.
What is the mature cell in cartilage called?
Chondrocyte
What occurs during the early stages of chondrogenesis involving chondroblasts?
Mitosis and early differentiation of chondroblasts.
What are the components of the matrix surrounding chondrocytes during interstitial growth?
The matrix components surrounding chondrocytes include the territorial matrix and the wider interterritorial matrix.
What provides strength to the cartilage matrix?
Collagen fibers.
What are the cells called that are found in cartilage, and what is their function?
The cells are called chondrocytes, and they synthesize and maintain ECM components.
What type of cartilage is found in the trachea?
Hyaline cartilage
What is the most important proteoglycan monomer in hyaline cartilage?
Aggrecan.
What separates the calcified zone from the deep (radial) zone in cartilage?
A smooth undulating, heavily calcified line called the tidemark.
What is the characteristic of the superficial (tangential) zone of cartilage?
It is a pressure-resistant region closest to the articular surface, containing elongated and flattened chondrocytes surrounded by type II collagen fibrils arranged in parallel fascicles.
How does hyaline cartilage contribute to joint movement?
It provides a lubricated surface for movable joints.
Which zone of the articular cartilage contains elongated and flattened chondrocytes?
The superficial (tangential) zone.
What is hyaline cartilage?
Hyaline cartilage is a type of cartilage that is smooth, glassy, and translucent, found in areas like the nose, trachea, and at the ends of long bones.
Where is fibrocartilage predominantly found in the body?
Intervertebral disks, articular disks of the knee, mandible, sternoclavicular joints, and pubic symphysis
What is the perichondrium?
The perichondrium is the dense layer of connective tissue that surrounds cartilage.
What is appositional growth in cartilage?
Appositional growth is the process where new cartilage is added to the surface of existing cartilage by chondroblasts from the perichondrium.
What is interstitial growth in cartilage?
Interstitial growth is the process where cartilage expands from within as chondrocytes divide and produce new matrix.
What distinguishes fibrocartilage in intervertebral discs from other types of cartilage?
The presence of densely packed collagen fibers which provide tensile strength and resilience.
Which layer of cartilage is responsible for chondroblast formation?
Chondrogenic layer
What role does the organic component of the bone matrix play?
It resists tension.
What type of tissue unites the syndesmoses joints between the flat bones of the skull?
Connective tissue.
What happens to the matrix during intramembranous ossification?
The matrix becomes calcified.
What type of bone formation process is depicted in the image?
Intramembranous ossification.
What processes are responsible for remodeling the spicules of bone?
Osteoclasts and osteoblasts
What structure is indicated by the arrows in the image?
Secondary ossification centers.
What types of collagen fibers and proteoglycans are characteristic of fibrocartilage?
Type I and II collagen fibers and versican (a proteoglycan secreted by fibroblasts).
What is a 'lacuna' in cartilage?
A small cavity that houses a chondrocyte
What components make up the organic part of the bone matrix?
Type I collagen fibers, proteoglycans enriched in chondroitin sulfate and keratan sulfate, hyaluronic acid, glycoproteins (osteocalcin, osteopontin, osteonectin, bone sialoprotein).
What abilities do osteoprogenitor cells retain?
They retain their mitosis ability and have the potential to differentiate into osteoblasts.
Which type of bone cell is responsible for bone resorption?
Osteoclasts
What is the function of canaliculi in compact bone?
They house processes of osteocytes, allow communication between osteocytes, and serve for the passage of substances between osteocytes and blood vessels.
What is the location of the inner circumferential lamellae in compact bone?
Around the bone marrow.
What are the small spaces labeled 'L' in the images?
Lacunae, which house osteocytes.
What is absent in spongy/cancellous bone that is typically found in compact bone?
Haversian system.
What type of joint is depicted in the image?
Synovial joint
What are the two types of cells found in the synovial membrane?
Type A cells (phagocytic macrophages) and Type B cells (secrete synovial fluid).
What are the two steps involved in endochondral ossification?
What do mesenchymal cells differentiate into during endochondral ossification?
Chondroblasts that produce the cartilage model.
What happens to the epiphyseal plate when an individual achieves maximal growth?
Proliferation of new cartilage within the epiphyseal plate terminates.
What is the precursor for all types of cartilage in chondrogenesis?
Mesenchyme.
What is interstitial growth in cartilage?
Growth from chondrocytes within cartilage, where isogenous groups generate matrix, are pushed away from each other, form separate lacunae, and thus enlarge the cartilage from within.
What are the primary functions of bone tissue?
Support and protection for the body and its organs.
What are 'isogeneous groups'?
Clusters of chondrocytes originating from the same parent cell
What are the four major cellular components of bone tissue?
Osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts.
What are the main functions of osteoblasts?
Osteoblasts originate from mesenchyme, develop under the influence of BMP and TGFβ, and synthesize the organic matrix of bone, including collagen type I, proteoglycans, and glycoproteins.
What is the purpose of Volkmann’s canals in compact bone?
They connect Haversian canals to one another.
What is the purpose of the articular cartilage in a synovial joint?
Articular cartilage covers the ends of bones in synovial joints to reduce friction and absorb shock.
What is the state of the diaphyses at birth?
Largely ossified.
Which zone in endochondral ossification is involved in the proliferation of chondrocytes?
Proliferative zone.
What are the key stages of endochondral ossification?
The key stages include the formation of a hyaline cartilage model, the calcification of the cartilage, the development of primary ossification centers, and the eventual replacement of cartilage by bone tissue.
What is the primary function of elastic cartilage?
Provides flexible support.
How does appositional growth contribute to the development of cartilage?
Appositional growth involves chondroblasts in the perichondrium differentiating and secreting extracellular matrix, leading to the addition of new layers of cartilage at the surface, increasing the size of the existing cartilage mass.
What is the function of osteoclasts in bone tissue?
Osteoclasts are responsible for the resorption of bone.
What are the origins of osteocytes?
Osteocytes originate from osteoblasts.
How do local acidic conditions affect hydroxyapatite in bone resorption?
They break up hydroxyapatite, releasing soluble Ca++ and PO4- ions.
What are the components of the periosteum?
The periosteum consists of an outer dense fibrous connective tissue rich in blood vessels and an inner cellular layer containing osteoprogenitor cells and osteoblasts.
Where is the periosteum located in a bone?
The periosteum is a membrane that covers the outer surface of all bones, except at the joints of long bones.
Where do the trabeculae of spongy bone protrude?
From the internal surface of compact bone into the marrow cavity.
What is the central structure labeled 'H' in the left image?
Haversian canal (also known as the central canal).
What are the structural components of spongy/cancellous bone?
Branching bony trabeculae and spicules.
What are the characteristics of primary bone?
Primary bone has abundant osteocytes, irregular bundles of collagen, and less mineral content.
What is the first step in endochondral ossification?
The proliferation and aggregation of mesenchymal cells at the site of the future bone.
What is the only part of the diaphysis that remains cartilage?
The epiphyseal plates
What type of cartilage is shown in the image?
Hyaline cartilage.
What occurs in the Zone of Hypertrophy in endochondral ossification?
Cartilage cells enlarge greatly (hypertrophy) and glycogen accumulates within the cells.
What type of cartilage is shown in the section of the pubic symphysis?
Fibrocartilage.
What cellular component is indicated by the letter 'C' in the images?
Chondrocytes.
What type of cell is referred to as a 'chondroblast'?
A cell that produces cartilage matrix
What role does the parathyroid hormone play in bone resorption?
It stimulates the secretion of osteoprotegerin ligand, leading to the differentiation of preosteoclasts into osteoclasts, and it secretes osteoclast-stimulating factors for bone resorption.
What characterizes spongy or cancellous bone?
Branching bony trabeculae and spicules with interconnecting cavities that protrude from the internal surface of compact bone into the marrow cavity.
What is the main structural unit of compact bone?
The osteon or Haversian system.
In which type of tissue does intramembranous ossification occur?
Richly vascularized mesenchymal tissue.
What happens to mesenchymal cells during intramembranous ossification?
Mesenchymal cells migrate, aggregate in specific areas, condense, and differentiate into osteoblasts.
Which cells are responsible for forming new bone in intramembranous ossification?
Osteoblasts.
What happens to the perichondrium during endochondral ossification?
It becomes vascularized, is replaced with periosteum, and produces osteoblasts.
Which type of cartilage is indicated in the provided image?
Hyaline cartilage
What characterizes the Zone of Reserve Cartilage in endochondral ossification?
Randomly distributed chondrocytes.
What type of tissue is bone tissue classified as?
Specialized connective tissue.
What is the 'interteritorial matrix'?
The matrix in between the lacunae containing chondrocytes
Where are osteocytes found within the bone?
Osteocytes are trapped in mineralized bone and lie within small cavities called lacunae.
What are the three types of bone cells shown in the image?
Osteoblasts, osteocytes, and osteoclasts
What is found within the medullary cavity of a bone?
The medullary cavity contains yellow bone marrow.
What structures surround the central canal in a Haversian system?
Concentric lamellae.
What are osteocytes and where are they located in compact bone?
Osteocytes are mature bone cells located within lacunae, which are small spaces within the lamellae of compact bone.
What is the internal lining of the joint capsule called?
The synovium.
What is the role of osteoprogenitor cells in intramembranous ossification?
They come into apposition with the initially formed spicules, become osteoblasts, and secrete more matrix.
What are the primary and secondary centers of ossification in endochondral ossification?
The primary ossification center is in the diaphysis, while the secondary ossification centers are in the epiphyses.
How does a bone grow in length while retaining its general shape?
Bone resorption occurs on some surfaces, and bone deposition occurs on other surfaces.
What is the term for the outer layer surrounding cartilage?
Perichondrium
What is the 'teritorial matrix' in cartilage?
The matrix surrounding individual chondrocytes
Which bone cell type is responsible for the formation of new bone?
Osteoblasts.
What enzyme forms carbonic acid during bone resorption?
Carbonic acid anhydrase.
What are the two main types of bone tissue?
Compact bone and spongy (cancellous) bone.
What is a key feature of compact bone?
It is dense tissue without cavities.
What type of bone tissue is shown in the image?
Compact bone.
What is primary bone and when is it formed?
Primary bone, also known as immature or woven bone, is the first bone formed during fetal development and during bone repair.
What type of tissue unites the synchondroses joints between the ribs and sternum?
Hyaline cartilage.
When is the first evidence of intramembranous ossification seen?
Around the 8th week of gestation.
What happens to osteoblasts when they become trapped in the matrix?
They become osteocytes.
What is the result of calcification of the cartilage matrix in endochondral ossification?
Calcification inhibits diffusion of nutrients, causing the death of chondrocytes and producing a large cavity.
When does the secondary ossification center develop in most bones?
During the first few years after birth.
How does bone increase in width or diameter?
By appositional growth of new bone between cortical lamellae and periosteum.
Where is hyaline cartilage typically located?
Fetal skeletal tissue, epiphyseal plates, articular surface of synovial joints, costal cartilages of rib cage, cartilages of nasal cavity, larynx (thyroid, cricoid, and arytenoid), rings of trachea, and plates in bronchi.
What does bone tissue serve as a reservoir for?
Minerals Ca & P.
What type of bone cell is found in lacunae?
Osteocytes
What is the endosteum and where is it located?
The endosteum lines the cavities in the bone, including the marrow cavity and extending into all cavities of the bone.
Where is the outer circumferential lamellae located in compact bone?
Beneath the periosteum.
How is secondary bone different from primary bone?
Secondary bone, also known as mature or lamellar bone, has concentric lamellae, a regular dispersion of osteocytes in their lacunae with radiating and branching canaliculi, and is more calcified.
What types of bones are commonly formed through endochondral ossification?
Most long and short bones.
What do mesenchymal cells secrete once they differentiate into osteoblasts during intramembranous ossification?
They secrete collagens, bone sialoproteins, osteocalcin, and other bone components (osteoid).
When does the early stage of endochondral bone formation begin in the fetus?
At about the 12th week of gestation.
What role does alkaline phosphatase play in endochondral ossification?
Hypertrophic cells synthesize alkaline phosphatase, leading to calcification of the surrounding cartilage matrix.
What is endochondral ossification?
Endochondral ossification is the process by which bone tissue is formed through the replacement of hyaline cartilage.
What cells in the periosteum differentiate into osteoblasts?
Osteoprogenitor cells.
How does the marrow cavity enlarge?
By resorption of bone on the endosteal surface of the cortical bone.
What is the role of the outermost cells of the perichondrium in developing cartilage?
The outermost cells of the developing cartilage are spindle-shaped and situated in a poorly fibrous layer called the perichondrium, acting as a transitional zone between cartilage and the surrounding general connective tissue.
What is the primary component of the inorganic part of the bone matrix?
Deposits of Ca-PO4 with the crystalline characteristics of hydroxyapatite.
What is the primary function of osteoclasts?
Osteoclasts are responsible for bone resorption and remodeling.
What are interstitial lamellae and where are they found?
Interstitial lamellae are remnants of remodeled osteons found between the osteons, remaining as irregular arcs of lamellar fragments.
How are the lamellae arranged in spongy/cancellous bone?
In an irregular arrangement.
What are synarthroses and diarthroses in joints?
Synarthroses permit limited movement, while diarthroses permit free movement.
What is the function of the synovial membrane in a synovial joint?
The synovial membrane produces synovial fluid, which lubricates the joint.
What are the primary components of synovial fluid?
Hyaluronic acid and lubricin.
What happens to chondrocytes in the midregion of the cartilage model during endochondral ossification?
They become hypertrophic.
What does growth in the length of long bones depend on?
The presence of the epiphyseal growth plate.
What is the role of secondary ossification centers?
They are responsible for the formation of bone tissue during the process of endochondral ossification.
What happens in the Zone of Proliferation during endochondral ossification?
Cartilage cells undergo division and organize into distinct columns.
What process occurs in the hypertrophic zone during endochondral ossification?
Secretion and calcification of the matrix.
What is the function of the inner layer of the perichondrium?
The inner layer of the perichondrium, the chondrogenic layer, contains cells called chondroblasts, which synthesize and secrete type II collagen, proteoglycans, and other extracellular matrix components.
What can stimulate and inhibit osteoclast resorption of bone?
Parathormone can stimulate it, and calcitonin can inhibit it.
What is the periosteum and where is it located?
The periosteum is an external surface covering of the bone.
What is the function of canaliculi in compact bone?
Canaliculi connect osteocytes within an osteon, allowing for nutrient and waste exchange.
What replaces woven bone during intramembranous ossification?
Lamellar bone replaces woven bone as compact and spongy bone form.
What initiates the formation of a new osteon in the osteonal system?
The formation of a tunnel-like space or resorption cavity by osteoclasts.
What remains relatively constant during bone growth?
The thickness of the epiphyseal plate.
How is a secondary osteon formed?
A secondary osteon forms from a primary osteon by the creation of concentric lamellae, featuring a central (Haversian) canal containing capillaries and nerve fibers.
What are the main zones involved in endochondral ossification?
Resting zone, proliferative zone, and hypertrophic zone.
What type of cartilage is involved in endochondral ossification?
Hyaline cartilage
What is contained within the central (Haversian) canal of a primary osteon?
A capillary, nerve fiber, and perivascular (progenitor) cells.
How do osteoblasts contribute to the increase in local concentrations of PO4- and Ca++?
Osteoblasts secrete alkaline phosphatase, which increases local PO4- and Ca++ concentrations.
How does mineral deposition increase during bone mineralization?
Mineral deposition increases by accretion around the matrix vesicles leading to confluently mineralized matrix vesicles and eventually fully mineralized bone.
What is the development of the osteonal system associated with?
Internal remodeling.
What is the significance of matrix vesicles in the process of bone mineralization?
Osteoblasts secrete matrix vesicles into the bony matrix that accumulate Ca++ and PO4- ions, leading to the crystallization of CaPO4 and matrix mineralization by deposition of hydroxyapatite crystals.
What replaces the fibrocartilage in the weeks following a fracture?
Trabeculae of woven bone, forming a hard callus.
What happens to the woven bone after the formation of the hard callus?
It is remodeled as compact and cancellous bone, and fully functional vasculature is reestablished.
From what two sources can compact bone be formed?
What is the first stage in the formation of a primary osteon (Haversian system)?
Osteoblasts line the marrow space of primary osteons.
What happens after the outer circumferential lamellae are laid down by periosteal osteoblasts?
Additional circumferential lamellae are formed by the periosteum, while osteoclastic activity leads to bone resorption in other areas.
How is compact bone formed from fetal spongy bone?
By continued deposition of bone on spongy bone spicules.
What replaces the hematoma during bone tissue repair?
A soft fibrocartilage-like mass of procallus tissue rich in collagen and fibroblasts.
What occupies the tunnel formed by osteoclasts during the development of a new osteon?
Blood vessels and surrounding connective tissue.
What forms the concentric lamellae in a developing primary osteon?
The transformation of woven bone of primary cancellous bone into compact bone.
What role does osteocalcin play in the mineralization of osteoid?
Osteocalcin binds extracellular Ca++ ions, leading to a high local concentration.
What is the role of osteoblasts in the process of mineralization?
Osteoblasts are responsible for producing the extracellular matrix and initiating the process of mineralization.
How do osteoblasts contribute to the formation of a new osteon?
Osteoblasts fill the canal by depositing osteoid on its wall in successive lamellae.
What role does the periosteum play if broken during bone tissue repair?
The periosteum reestablishes continuity over the procallus tissue.
What invades the soft procallus during bone tissue repair?
Regrowing blood vessels and osteoblasts.
What happens to bone development in young persons and adults?
In young persons, bone development is fast. In adults, bone development slows upon the closure of the epiphyseal plate.
What is the first step in bone tissue repair?
Tissue destruction and formation of a hematoma due to torn blood vessels.
What are the early stages of mineralization in bone tissue?
The early stages include the formation of matrix vesicles and the initial mineralization of these vesicles.
What is the initial step in the growth in width of a bone and osteon remodeling?
Outer circumferential lamellae are laid down by periosteal osteoblasts around the original trabeculae of primary cancellous bone.
