What is the primary function of yellow bone marrow?
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To store fat.
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What is the primary function of yellow bone marrow?
To store fat.
What is an Advanced Primary Ossification Center?
The area in a developing bone where ossification begins and progresses.
What inhibits the diffusion of nutrients in endochondral ossification?
Calcified cartilage matrix.
What must happen for newly formed osteoclasts to become bone resorbing cells?
They must be activated, a process involving osteoblasts.
What happens to the cartilage matrix in the Zone of Hypertrophy?
It gets compressed into bands between the chondrocyte columns.
What are the characteristics of bones in terms of shape and size?
Bones come in a variety of shapes and sizes.
What type of cartilage is found in the growth plate?
Calcified cartilage.
Where is yellow bone marrow primarily located?
In the medullary cavity of long bones.
What causes the actual lengthening of bone?
New cartilage formation pushes the epiphysis away from the diaphysis.
What is the main difference between decalcified and ground sections of bone?
Decalcified sections involve removing calcium, while ground sections involve grinding the bone to a thin layer without removing minerals.
What is calcified cartilage?
A type of cartilage that has undergone calcification, making it more rigid.
How does Woven Bone differ from Lamellar Bone?
Woven Bone has a less organized structure compared to Lamellar Bone.
What do osteoblasts lay down around the mid part of the cartilage model?
A cuff of bone known as the bony collar.
What is the first sign of ossification?
The formation of the bony collar.
What leads to the migration of cells into the cavity during endochondral ossification?
Blood vessel growth into the cavity.
What role do osteoblasts play in relation to osteoclasts?
Osteoblasts are involved in the activation process of osteoclasts.
What is the purpose of ground sectioning of bone?
To create thin slices of bone for detailed histological analysis.
What is another name for Woven Bone?
Immature Bone.
What are the two types of bone tissue?
Mature Bone and Immature Bone.
What is another name for Immature Bone?
Non Lamellar Bone, Bundle Bone, or Woven Bone.
What are lacunae in mature compact bone?
Small hollows within the matrix where osteocytes are located.
What type of bone is characterized by a porous structure and is found at the ends of long bones?
Trabecular bone.
What is endochondral ossification?
A process where bone develops by replacing hyaline cartilage.
What are Mixed Spicules?
Structures formed during ossification that contain both cartilage and bone.
What is the consequence of chondrocyte death in the cartilage model?
Matrix breakdown.
What are the characteristics of Immature Bone?
Large numbers of randomly arranged cells, randomly arranged collagen bundles, more ground substance than mature bone, and not heavily mineralized.
What is the function of osteoclast cells?
They are responsible for bone resorption, breaking down bone tissue.
What is Howship’s Lacuna?
A small cavity or depression in bone where osteoclasts reside and perform bone resorption.
What is an osteon?
The basic structural unit of compact bone.
What is the Haversian canal?
A central canal in an osteon that contains blood vessels and nerves.
What do interstitial lamellae represent?
Remnants of old osteons found between newer osteons.
What is a decalcified bone preparation?
A method used to prepare bone samples by removing calcium to allow for microscopic examination.
What are Sharpey's fibers?
Fibers that enter the bone matrix obliquely.
Where do Sharpey's fibers extend into the bone matrix?
Into the outer circumferential and interstitial lamellae.
How are osteons arranged in mature compact bone?
They are arranged with their long axis parallel to the long axis of the bone.
What are osteons?
Structural units of compact bone, consisting of concentric lamellae surrounding a central canal.
What runs parallel to the long axis of the bone in osteons?
Haversian canals.
How is collagen arranged in concentric lamellae of osteons?
Collagen fibers are laid parallel to one another in any given lamella.
What are Outer Circumferential Lamellae?
Layers of bone tissue that encircle the outer surface of the bone, providing structural support.
What demarcates the boundary of an osteon?
Cement lines.
What happens to the cartilage model during bone development?
It is almost entirely transformed into bone.
Where is the remaining cartilage found after the transformation of the cartilage model?
In the epiphyseal disk and at the articular surface.
What is the mineralization level of Woven Bone?
It is less mineralized than Lamellar Bone.
What is a bone spicule?
A small, needle-like structure in bone that contributes to its overall architecture.
How do Volkmann’s Canals connect Haversian canals?
They connect Haversian canals to each other.
What happens to cartilage as bone is laid down on calcified spicules?
The cartilage is resorbed, leaving spongy bone.
What do canaliculi contain?
Processes of osteocytes in living bone tissue.
What is mature spongy bone?
It is a type of bone that has a porous structure, found mainly at the ends of long bones and in the interior of others.
How is spongy bone remodeled?
Through osteoclastic activity and the addition of new bone.
What is notable about the internal and external structure of bones?
Bones have a complex internal and external structure.
What are the main components of mature compact bone structure?
Osteons or Haversian Systems, Haversian Canals, Volkmann’s Canals, Interstitial Lamellae, Circumferential Lamellae.
What do periosteal mesenchymal cells differentiate into?
Osteoprogenitor cells.
What part of the cartilage model is replaced by bone during endochondral ossification?
The mid part of the cartilage model, known as the diaphysis.
What results from further growth and remodeling during intramembranous ossification?
Replacement of woven bone by compact bone in the periphery and spongy bone in the center.
What is the organic matrix of bone made up of?
The organic matrix is mainly composed of collagen fibers and non-collagenous proteins.
Where is red bone marrow primarily found?
In the spaces of trabecular bone.
When does endochondral bone growth begin?
In the 2nd trimester.
Until when does endochondral bone growth continue?
Into early adulthood.
What role does water play in bone composition?
Water helps maintain the structure and function of bone tissue.
What is the role of the epiphyseal growth plate in long bone growth?
It is essential for growth in length.
What can osteoprogenitor cells differentiate into?
Osteoblasts and chondroblasts.
What happens to the thickness of the epiphyseal growth plate during growth?
It remains constant.
What happens to osteoid after it is formed?
It later calcifies, and osteoblasts become trapped in lacunae, turning into osteocytes.
What is the function of the proliferative zone in the growth plate?
Chondrocytes rapidly divide and contribute to the lengthening of the bone.
Where is the Epiphyseal Plate located?
In the metaphysis at each end of a long bone.
What replaces resorbed cartilage in the epiphyseal growth plate?
Spongy bone.
What happens in the hypertrophic zone of the growth plate?
Chondrocytes enlarge and prepare for the process of ossification.
What is the arrangement of collagen fibers between adjacent lamellae?
The fibers are arranged in different directions.
What are the two possible fates of the remaining bone component of a mixed spicule?
It may continue to grow by appositional growth or undergo resorption.
What are Volkmann’s Canals?
Channels that allow blood vessels and nerves to travel from the periosteum and endosteum to the Haversian canal.
What do osteoprogenitor cells become when they contact calcified cartilage spicules?
They become osteoblasts.
Where can woven bone be found in adults?
In alveolar sockets.
What lines Volkmann’s Canals?
Endosteal cells.
What happens to canaliculi in terms of connectivity?
Canaliculi may anastomose with each other.
What is the combination of bone and the underlying calcified cartilage called?
A mixed spicule.
What do periosteal cells differentiate into during bone growth?
Osteoblasts.
What is another name for the epiphyseal growth plate?
Growth plate.
What is the structure of collagen fibers in osteoid during the initial stage?
They form a woven network without a preferential orientation.
What does the plasma membrane of osteoclasts do in the Clear Zone?
Forms a tight seal with the bone matrix.
Why are osteoprogenitor cells important?
They are important for bone repair and cartilage formation in fracture sites.
What is the transverse disc between the epiphyseal and diaphyseal cavities called?
Epiphyseal growth plate or epiphyseal disc.
How do osteocytes communicate with each other?
By cytoplasmic processes.
What is red bone marrow composed of?
Blood cells in different stages of development and a network of reticular cells and fibers.
What do thick trabeculae in mature spongy bone contain?
Osteons.
Where is red marrow restricted to in mature adults?
Spaces of spongy bone in the sternum and iliac crest.
How many cell layers does the endosteum consist of?
One cell layer.
What do osteoblasts secrete?
Unmineralized bone matrix or osteoid.
What are the five cell types found in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Bone Lining Cells, and Osteoclasts.
What does the periosteum consist of in a bone where active bone formation is not in progress?
Mostly an outer fibrous layer of dense connective tissue, vessels, and nerves, with a poorly defined inner cellular layer.
How do osteocytes communicate with neighboring cells?
Through gap junctions.
What is spongy bone also known as?
Trabecular bone.
What is woven bone?
An immature form of bone that is formed quickly and has a haphazard organization of collagen fibers.
What type of cartilage is found in freely movable joints?
Hyaline cartilage.
What is formed as a result of osteoblast activity on calcified cartilage?
Mixed spicules are formed.
What does the secretion of alkaline phosphatase lead to?
Calcification of the cartilage matrix.
What characterizes Woven Bone?
It has a haphazard organization of collagen fibers.
What happens to transport vesicles in the basolateral region of osteoclasts?
They fuse with the cell membrane to release digested bone material.
What do chondrocytes in the Zone of Hypertrophy continue to secrete?
Cartilage matrix.
How many separate bones are there in an adult human body?
206 separate bones.
What is the primary function of the growth plate?
To facilitate the lengthening of bones during growth.
What is the function of canaliculi in bone tissue?
They allow communication between osteocytes and serve as a passage for substances between osteocytes and blood vessels.
What is the ruffled border of osteoclasts?
Part of the cell in direct contact with the bone, containing numerous plasma membrane infoldings.
What type of structures are found in the ruffled border of osteoclasts?
Microvillous type structures.
What is the effect of the new cartilage matrix on bone length?
It elongates the bone.
What is abundant in the Clear Zone of osteoclasts?
Actin filaments.
How are actin filaments arranged in the Clear Zone?
In a ring-like structure surrounded by actin binding proteins.
What structures are formed as a result of the changes in epiphyseal cartilage?
Bone spicules, trabeculae, and bone marrow.
What is the term for the end part of a long bone?
Epiphysis.
Where are osteocytes located?
In small spaces called lacunae within the bone matrix.
What types of blood cells are produced by bones?
Red and white blood cells.
What does the osteonal canal (Haversian canal) contain?
Blood vessels, nerves, and connective tissue.
What is the main shaft of a long bone referred to as?
Diaphysis.
What type of bone is characterized by a porous structure?
Trabecular Bone.
What is the primary function of yellow marrow?
It serves as a fat storage area in the bone.
What is a bone?
An organ of the skeletal system.
What is bone tissue?
A specialized connective tissue that is a structural component of bone.
Name some bone matrix proteins secreted by osteoblasts.
Calcium binding proteins, multiadhesive glycoproteins, proteoglycans, alkaline phosphatase.
What can osteoprogenitor cells differentiate into?
Osteoblasts.
What is cancellous bone?
A spongy type of bone found inside bones, characterized by a porous structure.
What is the characteristic staining property of osteoclasts?
They are highly acidophilic.
What is an osteon?
The basic structural unit of compact bone, consisting of a central canal surrounded by concentric layers of bone matrix.
How does the cartilage model increase in width?
By appositional growth.
What happens when osteoclastic bone resorption fails?
Increased bone mass.
What is the function of the basolateral region in osteoclasts?
It functions in the exocytosis of digested material.
What characterizes the chondrocytes in the Zone of Hypertrophy?
They are greatly enlarged and have clear cytoplasm due to glycogen accumulation.
When is Immature Bone formed?
Initially formed in the skeleton of a developing fetus.
In what direction do Volkmann’s Canals penetrate the bone?
Perpendicular to its long axis.
What do osteoblasts lay down on the cartilage spicule framework?
Osteoid.
What type of cells migrate into the cavity during endochondral ossification?
Periosteal mesenchymal cells and hemopoietic stem cells.
What is lamellar bone?
It is a mature bone tissue characterized by its organized structure, consisting of parallel layers of collagen fibers.
What is the largest bone in the human body?
The femur.
What is the cartilage remaining at the ends of the model called?
Proximal epiphyseal cartilage and distal epiphyseal cartilage.
What occurs to the cartilage that has already been produced after maximal growth?
It continues to deposit bone until no more cartilage is left.
What is the primary function of osteoblasts?
To form new bone by synthesizing and secreting the bone matrix.
What is compact bone?
A dense and strong type of bone that forms the outer layer of bones.
When does intramembranous ossification begin?
At the 8th week of gestation.
What is the region between the epiphysis and diaphysis called?
Metaphysis.
How is compact bone organized?
It is organized into structural units called osteons or Haversian systems.
What is the composition of compact bone?
It is primarily composed of mineralized matrix and collagen fibers.
What are the two surfaces of the epiphyseal plate?
Epiphyseal surface and diaphyseal surface.
Where are Endosteal Cells located?
On the internal bone surface.
How is the epiphyseal plate formed?
Through the proliferation and maturation of chondrocytes in the growth plate.
What is the second zone in the arrangement of the epiphyseal plate?
Proliferation zone.
What is another name for compact bone?
Cortical bone.
What is another name for bones formed through Intramembranous Ossification?
Membrane bone.
What forms around the cartilage model during endochondral ossification?
A bony collar.
What is the primary function of osteoblasts?
To initiate mineralization of bone matrix.
What is a primary ossification center?
The first area of a bone to start ossifying.
How do osteoblasts appear under light microscopy?
They are cuboidal or polygonal shaped.
What condition arises from the loss of balance between osteoclasts and osteoblasts?
Osteoporosis.
What does greater bone fragility in osteopetrosis lead to?
Increased risk of fractures.
What happens to the calcified cartilage component of a mixed spicule during endochondral ossification?
It gets removed.
What is a lamella?
Plates of collagen fibers cemented by the mineralized matrix.
How does periosteal connective tissue align in relation to the bone surface?
It generally runs parallel to the bone surface.
How do blood vessels grow into the cavities during endochondral ossification?
Through the bony collar.
How is the bony collar formed?
By intramembranous ossification.
What does newly formed bone appear as during intramembranous ossification?
Irregularly shaped spicules and trabeculae.
What characterizes the Resting Zone or Zone of Reserved Cartilage in the growth plate?
No cell proliferation or active matrix production.
What do hemopoietic stem cells give rise to?
All blood cells.
What is the smallest bone in the human body?
The stapes in the middle ear.
What do chondrocytes in the Zone of Proliferation actively produce?
Cartilage matrix.
What is the zonal arrangement of growth plate cartilage cells?
It refers to the organization of cartilage cells in distinct layers within the growth plate.
What do osteoblasts secrete to initiate bone formation?
Osteoid, which is the unmineralized organic component of the bone matrix.
What happens to osteoblasts once they become surrounded by bone matrix?
They differentiate into osteocytes.
What does the marrow cavity contain?
Red bone marrow and yellow bone marrow.
What is the function of the osteocytic process?
To communicate with other bone cells and exchange nutrients.
How do bones assist in muscle movement?
By providing attachment to muscles and functioning as levers.
Where are Periosteal Cells located?
On the external bone surface.
What covers the outer surface of bones?
Periosteum, except in areas where they articulate with another bone.
What are the five cell types in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Bone Lining Cells, Osteoclasts.
What characterizes Intramembranous Ossification?
Mesenchymal tissue is directly replaced by bone without a cartilage model.
What are examples of bones formed through Intramembranous Ossification?
Bones of the skull and face, mandible, flat portion of the clavicle.
What is the fourth zone in the arrangement of the epiphyseal plate?
Calcification zone.
What are the five cell types in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Bone Lining Cells, Osteoclasts.
What mineral is primarily found in bone tissue?
Calcium phosphate.
What do mesenchymal cells differentiate into under the influence of BMPs?
Chondroblasts.
What occupies the spaces within the meshwork of spongy bone?
Marrow and blood vessels.
What is the role of the epiphyseal plate in bone growth?
It allows for the lengthening of bones during growth.
What occurs to the cartilage matrix during the process of hypertrophy?
It becomes thin and irregular between large cells.
What does the arrangement of collagen fibers provide to the osteons?
It provides strength to the osteons.
What happens to the perichondrium after the cartilage model is fully established?
It stops producing chondrocytes and instead forms osteoblasts.
What is interstitial lamella?
It is the remnants of old osteons found between newer osteons in mature bone.
What characterizes mature compact bone?
It is dense and forms the outer layer of bones, providing strength and support.
What surrounds Volkmann’s Canals?
They are not surrounded by concentric lamellae.
What is the perichondrium called after it transforms?
Periosteum.
What are the main components of bone?
Bone is primarily composed of organic matrix, inorganic minerals, and water.
What is osteoid?
The unmineralized organic component of bone matrix.
What do osteoblasts form during the appositional growth of bone?
Bony ridges.
What do bony ridges enclose during bone growth?
Blood vessels.
What happens to the epiphyseal and diaphyseal marrow cavities when growth ceases?
They become confluent.
What is the site of epiphyseal cartilage called after growth cessation?
Epiphyseal line.
What is the relationship between new cartilage production and resorption at the epiphyseal plate?
The amount of new cartilage produced equals the amount resorbed.
What is a key feature of mature spongy bone regarding marrow spaces?
Numerous marrow spaces of various sizes are present.
Where do Sharpey's fibers extend into?
The outer circumferential and interstitial lamellae, but not into the osteons.
What is the Epiphyseal Line?
The remnant of the epiphyseal plate in adults who have stopped growing.
What role do bones play in relation to gravity?
They support the body against gravity and enable movement.
How many distinct zones are present in a growing epiphyseal plate?
Five distinct zones.
What covers the articular surfaces of bones in a movable joint?
Hyaline cartilage.
Where is the compact or dense layer of bone found?
Forms the outside of the bone.
What are the characteristics of osteocytes?
Mature bone cells that are non-dividing, completely surrounded by bone matrix, and occupy individual lacunae.
Where is the spongy or cancellous layer located?
Found on the inner aspect of bone.
What is intramembranous ossification?
A process of bone formation that occurs directly within a membrane.
What is the role of the periosteum in endochondral ossification?
It provides a surface for the attachment of muscles and helps in the formation of new bone.
What is lamellar bone?
A mature bone that has a regular, organized structure with layers of collagen fibers.
What do chondroblasts lay down during endochondral ossification?
A hyaline cartilage model of the future bone.
What is the result of chondrocyte hypertrophy?
Resorption of the cartilage matrix around the large cells.
What treatment may be necessary for severe osteopetrosis?
Hematopoietic stem cell or bone marrow transplant from an allogenic donor.
What is a mixed spicule?
A structure that contains both cartilage and bone components.
What are the two layers of the periosteum?
Inner cellular layer and outer fibrous layer.
What happens to neighboring lacunae after chondrocyte death?
They become confluent to produce large cavities.
What are the three regions of an actively resorbing osteoclast cell?
Ruffled border, Clear zone (or Sealing zone), and Basolateral zone.
How are canaliculi arranged in relation to the Haversian canal?
They are arranged radially to the Haversian canal.
What is the first site where bone begins to form in the diaphysis of a long bone called?
The primary ossification center.
What is woven bone?
A type of bone that is formed quickly and has a haphazard organization of collagen fibers.
What is the primary function of red bone marrow?
To produce blood cells.
What inorganic minerals are primarily found in bone?
The primary inorganic mineral in bone is hydroxyapatite, which contains calcium and phosphate.
What are the two types of epiphyseal cartilage?
Proximal epiphyseal cartilage and distal epiphyseal cartilage.
What happens to the periosteum where tendons and ligaments attach?
It is subject to stress and can prevent separation or tearing.
What is an osteocyte?
A mature bone cell that maintains the bone matrix.
What are the five cell types in bone tissue?
Osteoprogenitor cells, osteoblasts, osteocytes, bone lining cells, and osteoclasts.
What do osteons consist of?
Concentric lamellae of bone matrix surrounding a central canal called the osteonal canal.
What is a lamella?
Plates of collagen fibers cemented by mineralized matrix.
What lines the inner aspect of compact bone facing the marrow cavity?
Endosteum.
Where is compact bone typically found?
In the diaphysis of long bones and the outer layer of other bones.
What minerals do bones store?
Calcium and phosphate.
How do Bone Lining Cells communicate with each other and osteocytes?
Through gap junctions.
What characterizes bone tissue?
Mineralized extracellular matrix.
What is compact bone?
A dense and strong type of bone that forms the outer layer of bones.
From what do osteoclasts derive?
From the fusion of mononuclear hemopoietic cells (monocyte cell lineage).
What invades the Zone of Resorption?
Small blood vessels and osteoprogenitor cells invade the region previously occupied by dying chondrocytes.
What is a secondary ossification center?
Areas of ossification that appear after the primary center, typically in the epiphyses.
How does bone grow in length?
Through the activity at the epiphyseal plate.
What is a hereditary bone disease associated with osteoclast dysfunction?
Osteopetrosis.
Why is bone characterized as specialized connective tissue?
Bone has a unique structure and function that supports and protects organs, facilitates movement, and stores minerals.
When is Woven Bone typically formed?
During fetal development and in the healing of fractures.
What is a trabecula of cartilage bone?
A small, beam-like structure in bone that is covered by cartilage.
What type of cartilage remains at the articular surface?
Articular cartilage.
What occurs at the attachment points of ligaments and tendons to bone?
The periosteum provides a strong connection.
What are trabeculae?
Structural elements found in spongy bone that form a network.
What is the primary ossification center?
The initial site where ossification begins in endochondral ossification.
What happens as more osteoblasts come into apposition with the new bone?
They add more bone matrix.
What is the diaphysis?
The part of the cartilage model that is replaced by bone during ossification.
What occupies the spaces between trabeculae in the bone?
Bone marrow.
What type of bone is formed by intramembranous ossification?
Woven bone.
What is laid down to form an osteon during bone growth?
Concentric lamellae of bone.
How do collagen fibers of tendons and ligaments interact with bone?
They run obliquely into the bone and merge with the collagen fibers of the extracellular bone matrix.
What is one of the primary functions of bone?
Supports and protects various organs of the body.
Where does intramembranous ossification occur within the embryo?
Within the embryonic mesenchyme.
What type of matrix is found in mature spongy bone?
Lamellate matrix.
What do mesenchymal cells differentiate into during intramembranous ossification?
Osteoprogenitor cells.
What transcription factor is involved in the differentiation of osteoprogenitor cells into osteoblasts?
CBFA1 (Core Binding Factor Alpha - 1).
What are the five cell types found in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Bone Lining Cells, Osteoclasts.
What are the two mechanisms of bone formation?
Intramembranous Ossification and Endochondral Ossification.
What do circumferential lamellae follow?
The entire inner and outer circumferences of the shaft of long bones.
What are the five cell types in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Bone Lining Cells, and Osteoclasts.
What is notable about the cytoplasm of Osteoprogenitor Cells?
It is inconspicuous.
What characterizes Endochondral Ossification?
A cartilage model serves as the precursor of the bone.
What is endochondral ossification?
A process where bone develops by replacing cartilage.
Where are osteoclasts located?
At sites where bone is resorbed.
What is another name for a resorption bay?
Howship’s lacuna.
What therapy is effective in treating osteoporosis?
Hormone replacement therapy (HRT).
What type of bone is also known as spongy bone?
Trabecular bone.
What is the process by which bone growth in width occurs?
Appositional growth at the bone surface.
What is the Clear Zone or Sealing Zone in osteoclasts?
A ring-like perimeter adjacent to the ruffled border that demarcates the bone area for resorption.
What do osteoblasts secrete during intramembranous ossification?
Type I collagen and matrix proteins, known as osteoid.
What is the state of osteoprogenitor cells?
They are resting cells.
Are lamellae present in the early stage of osteoid formation?
No, lamellae are not present at this stage.
How is the tissue arranged in mature spongy bone?
As trabeculae or spicules.
What is the term used for the bone formed during the initial stage of intramembranous ossification?
Woven bone.
What role do osteoblasts play in bone remodeling?
They are involved in the formation of new bone tissue during the remodeling process.
What is another name for the growth plate in long bones?
Epiphyseal Plate.
What are canaliculi?
Microscopic channels that connect lacunae and allow communication between osteocytes.
What type of bone is lined by endosteum within the marrow cavity?
Trabeculae of spongy bone.
What are the five cell types in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Bone Lining Cells, Osteoclasts.
What is the first zone in the arrangement of the epiphyseal plate?
Resting zone.
What is the shape of Osteoprogenitor Cells?
Flattened or squamous.
What are the main components of mature compact bone structure?
Osteons, Haversian canals, Volkmann’s canals, interstitial lamellae, and circumferential lamellae.
What are Haversian canals?
Canals that run through the osteons, containing blood vessels and nerves.
What is the fifth zone in the arrangement of the epiphyseal plate?
Resorption zone.
What are examples of bones formed through Endochondral Ossification?
Long bones, vertebrae, pelvis.
What are trabeculae?
Thin anastomosing spicules of bone tissue.
What is the Haversian system?
Another term for the osteon, referring to the system of canals and surrounding bone matrix in compact bone.
What do large hypertrophied chondrocytes secrete?
Alkaline phosphatase.
What is the ruffled border of osteoclasts?
A specialized structure that increases the surface area for bone resorption.
Where do canaliculi open into?
The Haversian canal.
What is the function of the increased surface area in the ruffled border?
To facilitate the release of hydrolytic enzymes and endocytosis of degraded bone debris.
What are osteoprogenitor cells derived from?
Mesenchymal stem cells in the bone marrow.
What is the Epiphyseal Plate?
A hyaline cartilage plate in the metaphysis at each end of a long bone, found in children and adolescents.
What is the significance of collagen in bone?
Collagen provides tensile strength and flexibility to the bone.
What occurs in the resting zone of the growth plate?
Chondrocytes are relatively inactive and serve as a reserve for future growth.
What is the primary function of compact bone?
To provide strength and support to the skeletal structure.
When does the secondary ossification center in the distal epiphyseal cartilage develop?
At a later time point after the proximal center.
What are secondary ossification centers?
Areas in bones where ossification occurs after primary ossification, typically in the epiphyses.
What happens to red marrow in mature adults?
It gets replaced with fat cells and is known as yellow marrow.
How do osteocytes, lacunae, and canaliculi in mature spongy bone compare to those in mature compact bone?
They resemble those of mature compact bone but are arranged differently.
What are the two distinct structural arrangements of bone tissue?
Compact (dense) layer and spongy (cancellous) layer.
Under what condition can yellow marrow revert to red marrow?
When stimulated, such as during extreme blood loss.
What are the components of the periosteum in an actively growing bone?
An outer fibrous layer of dense connective tissue, vessels, and nerves, and an inner cellular layer of osteoprogenitor cells.
What are periosteal cells?
Cells present in the inner cellular layer of the periosteum that can divide to become osteoblasts when stimulated.
What do osteocytes use to communicate with distant cells?
Signaling molecules such as nitric oxide.
What is the function of the long cell processes of osteocytes?
They extend into canaliculi to facilitate communication.
What type of collagen do chondroblasts express?
Type II collagen.
How does the cartilage model increase in length?
By interstitial growth.
What should matrix calcification not be confused with?
Bone matrix mineralization.
What are the main components of bone?
Bone is composed of cells, extracellular matrix, and mineralized components.
What occurs at the epiphyseal end while spongy bone is formed at the diaphyseal side?
New cartilage matrix is formed to maintain the thickness of the epiphyseal plate.
How do chondrocytes in the Zone of Proliferation compare to those in the Resting Zone?
Chondrocytes are larger than those in the reserve zone.
What is the main activity of chondrocytes in the Zone of Proliferation?
They divide and get organized into distinct columns.
What develops shortly after birth in endochondral ossification?
A secondary ossification center in the proximal epiphyseal cartilage.
What causes the development of the secondary ossification center?
Hypertrophy, degeneration, and calcification of the epiphyseal cartilage.
What are the main zones in the growth plate?
The zones include the resting zone, proliferative zone, hypertrophic zone, and ossification zone.
What remains at the ends of the bone after ossification?
Articular cartilage.
What are perforating fibers also known as?
Sharpey's fibers.
In which age group is the Epiphyseal Plate found?
In children and adolescents.
What are the two types of Bone Lining Cells?
Periosteal Cells and Endosteal Cells.
What is the epiphyseal plate?
A growth plate that allows for the lengthening of bones during development.
What is the function of articular cartilage?
To provide a smooth, lubricated surface for joint movement and to absorb shock.
What are interstitial lamellae?
Remnants of previous concentric lamellae located between osteons.
What is a lacuna?
A space in the bone matrix where the osteocyte is located.
What type of collagen is found in the osteoid?
Type I collagen.
What are the four types of bone cells?
Osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts.
What do active osteoblasts lay down on a bone trabecula?
Osteoid.
What are Volkmann’s canals?
Canals that connect Haversian canals and allow for communication between them.
In what form is calcium phosphate deposited in bone tissue?
As hydroxyapatite crystals (Ca10(PO4)6(OH)2).
What is a resorption bay?
A shallow bay where osteoclasts rest directly on bone tissue during resorption.
What happens to chondrocytes in the mid region of the cartilage during endochondral ossification?
They hypertrophy.
What is established during endochondral ossification?
The periosteal bony collar.
What happens to the proliferation of new cartilage in the epiphyseal plate when maximal growth is achieved?
It terminates.
What processes are enhanced by the ruffled border of osteoclasts?
Release of hydrolytic enzymes and endocytosis.
What is the composition of trabecular bone?
It consists of a lattice of trabeculae and contains red bone marrow.
What happens to the Epiphyseal Plate in adults?
It is replaced by the epiphyseal line once growth has stopped.
What are the main structural components of mature compact bone?
Osteons (Haversian Systems), Haversian Canals, Volkmann’s Canals, Interstitial Lamellae, Circumferential Lamellae.
What are the two types of bone tissue?
Mature Bone and Immature Bone.
What is the function of red marrow?
It is responsible for the production of blood cells.
What is the role of the ossification zone in the growth plate?
It is where cartilage is replaced by bone tissue.
What lines the Haversian canals?
Endosteum.
What types of cells are found in the endosteum lining the Haversian canals?
Osteoprogenitor and endosteal cells.
What type of bone is dense and forms the outer layer of bones?
Compact Bone.
What type of cells are primarily found in the endosteum?
Osteoprogenitor cells.
What is the third zone in the arrangement of the epiphyseal plate?
Hypertrophic zone.
What is the first stage of endochondral ossification?
Formation of cartilage models of developing bone.
What are the components of a bone?
Bone tissue and other connective tissues such as hemopoietic tissue, fat tissue, blood vessels, nerves, and cartilage.
What additional type of cells are present in the endosteum?
Endosteal cells.
What do osteoblasts secrete to aid in mineralization?
Small membrane-bound matrix vesicles containing alkaline phosphatase (ALP).
What do osteoblasts lay down on calcified cartilage spicules?
They lay down osteoid.
What is the normal balance in bone health?
Bone resorption by osteoclasts and bone formation by osteoblasts.
What is defective in osteopetrosis regarding bone remodeling?
The remodeling of woven bone to compact bone.
What is the origin of osteoblasts?
They originate from osteoprogenitor cells.
What is a trabecula?
A small rod or beam of bone tissue that forms the structural framework of spongy bone.
What components make up Mature Bone?
Osteons (Haversian systems), interstitial lamellae, and circumferential lamellae.
What does yellow bone marrow consist of?
Fat cells.
How can calcium and phosphate be utilized by the body?
They can be mobilized from the bone matrix and taken up by the blood as needed.
What role do secondary ossification centers play in bone development?
They contribute to the formation of the epiphyses and the overall shape of the bone.
How does the nucleus of Osteoprogenitor Cells appear?
Lightly staining with an elongate or ovoid shape.
What are osteoclasts?
Large, multinucleated cells involved in bone resorption.
When does endochondral ossification begin?
At the 8th week of gestation.
What occurs at the site of future bone during endochondral ossification?
Proliferation and aggregation of mesenchymal cells.
What do osteoprogenitor cells differentiate into in the Zone of Resorption?
They differentiate into osteoblasts.
How does bone grow in width?
Through appositional growth, where new bone is added to the outer surface.
What exacerbates osteoporosis in postmenopausal women?
Estrogen deficiency.
What happens to mesenchymal cells during intramembranous ossification?
They migrate and aggregate in specific areas, forming ossification centers.
What is another name for Mature Bone?
Lamellar Bone.
What is an osteon?
The basic structural unit of compact bone, consisting of a central canal surrounded by concentric rings of bone matrix.
How do mature compact bone and mature spongy bone differ in structure?
Both have the same lamellar structure, but spongy bone is arranged as trabeculae or spicules.
Where are Osteoprogenitor Cells located?
In the inner cellular layer of the periosteum and the endosteal lining of Haversian canal, Volkman’s canal, and marrow cavities.
What characterizes mature spongy bone?
It has a porous structure that provides strength while minimizing weight.
What is the shape of osteoprogenitor cells?
Flattened in shape.
What happens in the Zone of Calcified Cartilage?
The cartilage matrix gets calcified, hypertrophied cells degenerate, and calcified cartilage serves as a scaffold for new bone deposition.
What characterizes the Zone of Resorption?
It is near the diaphysis where calcified cartilage is in direct contact with the connective tissue of the marrow cavity.
What does the spongy bone consist of?
A sponge-like meshwork of trabeculae.
When are matrix vesicles secreted by osteoblasts?
Only when the matrix is produced, making it a regulated process.
How can osteoblasts be identified in tissue?
When arranged as a single layer of cells in apposition to newly forming bone.
What medication inhibits bone resorption?
Calcitonin.
