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65 Cards in this Set
- Front
- Back
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What is the most common type of cartilage in the body?
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Hyaline cartilage
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Where can hyaline cartilage be found?
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Nose, larynx, ventral side of ribs, tracheal rings, bronchi, movable joints (articulating surfaces)
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What are mesenchyme cells?
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Pluripotential undifferentiated cells that are present only in embryonic stages.
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What are chondroblasts? How do they contribute to cartilage development?
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Arise from congregated mesenchymal cells. They secrete and surround themselves in the matrix material of cartilage forming lacuna and becoming chondrocytes.
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What is the name given to the type of growth that occurs in cartilage?
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Interstitial growth ("growth from within")
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When is cartilage growth still important beyond early developmental stages?
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1. Articular cartilage replacement (no perichondrium present 2. Epiphyseal plate 3. Endochondral bone
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What is the perichondrium?
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Envelops the cartilage and is responsible for growth an maintenance.
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Where are fibroblasts found in cartilage and what is their function?
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Outer fibrous layer of perichondrium and they synthesize Type I Collagen
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Where are chondrogenic cells found in cartilage and what is their function?
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Compromise the innermost layer of perichondrium.Derived from mesenchyme, can divide and differentiate into chondroblasts.
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What is appositional growth?
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Growth in width of cartilage d/t chondroblasts laying down cartilage in periphery.
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What is meant by the term isogenous group?
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Refers to closely located (clustered) chondrocytes due to mitotic division. Usually found near the center of cartilage.
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What type of collagen is the primary constituent of cartilage?
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Type II
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Why does cartilage appear as a non-fibular, homogenous mass despite the fact that it contains collagen fibers?
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The fibers are small and have the same refractive index as ground substance.
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What 3 GAGs are most commonly found in cartilage?
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Chondroitin 4-sulfate, Chondroitin 6-sulfate and keratan sulfate.
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What is an aggrecan? What is a proteoglycan aggregate?
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1. Major cartilage proteoglycan consisting of many GAGs 2. Aggrecans assoc. w/hyaluronic acid which can in turn interact with collagen,
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What is meant by the term isogenous group?
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Refers to closely located (clustered) chondrocytes due to mitotic division. Usually found near the center of cartilage.
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What type of collagen is the primary constituent of cartilage?
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Type II
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Why does cartilage appear as a non-fibular, homogenous mass despite the fact that it contains collagen fibers?
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The fibers are small and have the same refractive index as ground substance.
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What 3 GAGs are most commonly found in cartilage?
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Chondroitin 4-sulfate, Chondroitin 6-sulfate and keratan sulfate.
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What is an aggrecan? What is a proteoglycan aggregate?
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1. Major cartilage proteoglycan consisting of many GAGs 2. Aggrecans assoc. w/hyaluronic acid which can in turn interact with collagen ("bottle brush")
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How is hydration of the cartilage matrix achieved?
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Negative charge of sulfate group on GAGs attracts H2O.
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Why does hyaline cartilage matrix stain basophilic?
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GAGs
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What is chondronectin?
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Adhesive protein binding various matrix components to the integrins present in chondroblasts/cytes.
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What types of changes in cartilage or associated with aging?
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Chondrocytes may atrophy causing calcification of the matrix. Chondroitin conc. dec. and keratan inc. Also, extensive damage may cause formation of connective scar tissue instead of cartilage.
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What component of elastic cartilage differs from hyaline cartilage?
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High proportion of elastic fibers.
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What type of stain can be used for elastin?
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Orcein
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What is the functional difference btw. elastin and hyaline cartilages? Where can elastic cartilage be found?
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External ear, epiglottis and larynx
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Describe the histological components of fibrocartilage?
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Characteristics of both hyaline cartilage and dense collagenous tissue. Has many parallel type I collagen fibers packed in bundles.
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How does fibrocartilage develop?
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Fibroblast secreting proteoglycan surround themselves in matrix. Then differentiate into chondrocytes. No perichondrium.
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What is the function and location of fibrocartilage?
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High tensile strength. Pubic symphysis, intervertebral discs, and where tendons and ligaments insert into bone.
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Name 3 organic components of bone.
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Collagen, glycoproteins and aggrecans.
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90% of organic material in bone is...
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Type I Collagen
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What is osteopontin, sialoprotein and osteocalcin.
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1. Binding sites for mineral components and integrins of bone cells 2. Binds Ca; Also binds cells to matrix 3. Binds Ca and may be involved in calcification
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What is the difference between aggregans found in hyaline cartilage and those found in bone? How does this effect staining?
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Smaller with fewer GAGs. Does not stain basophilic b/c aggrecans masked by abundant collagen in bone.
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What are hydroxyapatite crystals? How are they organized?
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Composed of Ca and phosphorus. Major mineral component of bone matrix. Deposited in ordered array along collagen, residing in the gaps.
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What is the hydration shell?
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Water surrounding hydroxyapatite crystals permitting exchange of ions with ECF.
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What is the periosteum? Describe it's two layers.
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Covers the outer surface of bone. Outer layer of dense irregular collagenous CT. Inner layer with osteoprogenitor cells.
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What is the endosteum?
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Lines bone cavities. Has osteoprogenitor cells and osteoblasts.
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What are osteoblasts?
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Derived from osteoprogenitor cells. Produce matrix organic components. Line up in single layer along bone surface.
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What is the role of osteocytes? Where are they located and how do they communicate?
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Derived from osteoblasts surrounded in matrix. Involved in maintenance of matrix. Found in lacuna. Connect to other cells through extensions into canaliculi using gap junctions.
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What are the only bone cells capable of mitotic division?
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Osteoprogenitor cells
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What are osteoprogenitor cells derived from? What can they become? Where are they located?
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Mesenchyme. Osteoblasts or chondroblasts. Inner layer of periosteum, endosteum, and lining Haversian canals.
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What are Howship's lacunae?
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Small depressions on bone surface where osteoclasts can be found.
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How are osteoclasts formed?
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Arise from mononuclear phagocytic blood cells.
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Where doe intramembranous bone formation occur?
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At condensations of mesenchymal tissue such as in flat bones and to increase the girth of long bones.
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What are spicules and trabeculae?
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Maze like network formed by accumulating matrix in intramembranous bone formation.
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What is osteoid?
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Initial matrix laid down but not yet calcified in IMBF.
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How do bones form from intramembranous bone formation?
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Growth of multiple primary ossification centers proceeds radially until fusion occurs (Re: fontanelles).
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What are two general steps in endochondrial bone formation?
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1. Hyaline cartilage laid 2. As cartilage grows it is simultaneously reabsorbed and replaced by bone.
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What is the diaphysis and epiphysis.
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1. Central, cylindrical shaft. 2. One at each end connected to diaphysis.
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What is the bone collar?
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Tube that forms on the outer boundary of diaphysis.
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Define osteogenic bud.
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A combination of blood vessels, osteoclasts and progenitor cells that penetrate the bone collar and invade cavities left by apoptosed chondrocytes.
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How does the bone marrow cavity form in the diaphysis?
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Osteoclasts
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What type of bone growth occurs in the diaphysis?
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Longitudinal
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How does the secondary ossification center differ from the primary?
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Occurs at each epiphysis. No bone collar develops and no periosteum is assoc. with the epiphysis.
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How does bone grow lengthwise?
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Cartilage at the epiphyseal plate contines to be deposited and chondrocytes proliferate on the epiphysis side while on the diaphysis side cartilage is being replaced w/bone.
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Name and briefly describe the 5 zones of the epiphyseal plate from epiphysis to diaphysis.
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1. ZO reserve cartilage 2. ZO proliferation (chondrocytes rapidly dividing, packed in rows) 3. ZO hypertrophy 4. Zone of calcification (chondrocyte apoptosis and hydroxyapatite deposit) 5. Zone of ossification (bone appears)
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What is appositional growth and what type of bone does it form?
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Increases width of diaphysis. Compact bone.
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What are lamellae?
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Concentric rings formed from collagen fiber depostion in compact bone.
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What is a haversian system or osteon?
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Serious of lamellae arranged as concentric rings around a haversian canal.
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What is a harvesian canal?
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Carries blood vessels and nerves.
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What are Volkmann's canals?
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Connect Haversian canals
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What is interstitial lamallae?
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Remnants of old osteons wedged btw. complete osteons.
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What is outer circumferential lamallae?
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Parallel layers of compact bone just deep to the periosteum.
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What is inner circumferential lamallae?
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Parallel layers of compact bone covering the marrow cavity side of bone.
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