1. Hyaline Cartilage 2. Elastic Cartilage 3. Fibrocartilage

MIDTERM: BONE AND CARTILAGE Flashcards by Chin Lys

A tough, durable form of supporting connective
tissue, characterized by an extracellular matrix (ECM) with high concentrations of GAGs and proteoglycans, interacting with collagen and elastic fibers.

cartilage

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has a firm consistency that allows the tissue to
bear mechanical stresses without permanent
distortion

cartilage

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provides cushioning and sliding regions
within skeletal joints and facilitates bone
movements

cartilage

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lack vascular supplies, Also lacks nerves

cartilage

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Embedded in the ECM which unlike connective
tissue proper contains no other cell types.
- Synthesize and maintain all ECM
components and are located in matrix cavities
called ________

chondrocytes, lacunae

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Cartilage consists of these cells

chondrocytes

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Chondrocytes receive nutrients by ________ in surrounding connective
tissue (the perichondrium).

diffusion from capillaries

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a sheath of dense connective tissue that surrounds cartilage

perichondrium

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harbors the blood supply serving the
cartilage and a small neural component

perichondrium

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PHYSICAL PROPERTIES OF CARTILAGE:

 TYPE II COLLAGEN FIBRILS
 HYALURONAN
 PROTEOGLYCANS

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covers the ends of bones in movable joints and which erodes in the course of arthritic degeneration
- Lacks perichondrium and is sustained by the diffusion of oxygen and nutrients from the synovial fluid

articular cartilage

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3 TYPES OF CARTILAGE

Hyaline Cartilage
Elastic Cartilage
Fibrocartilage

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Most common of the three types
- Homogeneous and semitransparent in the fresh state

hyaline cartilage

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__________,hyaline cartilage is located in the:
o articular surfaces of movable joints
o in the walls of larger respiratory passages (nose, larynx, trachea, bronchi)
o in the ventral ends of ribs, where they articulate with the sternum
o and in the epiphyseal plates of long boneswhere it makes possible longitudinal bone growth.

in adults

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__________,hyaline cartilage forms the temporary skeleton that is gradually replaced by bone.

in the Embryo

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a chronic condition that commonly occurs during aging
involves the gradual loss or changed physical properties of the hyaline cartilage that lines the articular ends of bones in joints.

Osteoarthritis

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The dry weight of hyaline cartilageis _________ collagen embedded in a firm, hydrated gel of proteoglycans and structural glycoproteins.

matrix, is nearly 40%

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most collagen in hyaline cartilage

type 2

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most abundant proteoglycan of hyaline cartilage
- bind further to the surface of type II collagen fibrils

aggrecan

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Structural multiadhesiveglycoprotein
- Binds specifically to GAGs, collagen and integrins mediating the adherence of chrondrocytes to the ECM

CHRONDRONECTIN

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makes matrix generally basophilic and thin collagen fibrils barely discernable

PROTEOGLYCANS:

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elliptic shape, with long axes parallel to the surface

CHONDROBLAST

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Common in aging
degenerative changes in the chondrocytes
resembles endochondral ossification by which bone is formed.

Calcification

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a pituitary-derive protein which is a major regulator of hyaline cartilage growth

Somatotropin or growth hormone

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acts indirectly, promoting the endocrine release from the liver of insulin-like growth factors, or somatomedins, which directly stimulate the cells of hyaline cartilage

Somatotropin or growth hormone

benign or slow growing tumor which cells produce normal matrix components.

Chondroma

malignant tumor which cells produce normal matrix components. - seldom metastasize and are generally removed surgically.

Chondrosarcoma

all hyaline cartilage is covered by a layer of dense connective tissue - essential for the growth and maintenance of cartilage

PERICHONDRIUM

consists largely of collagen type I fibers and fibroblasts

outer region of perichondrium

adjoining the cartilage matrix also contains mesenchymal stem cells

inner layer of perichondrium

similar to hyaline cartilage

elastic cartilage

contains an abundant network of elastic fibers in addition to a meshwork of collagen type II fibrils,

elastic cartilage

give fresh elastic cartilage a

yellowish color

More flexible than hyaline cartilage

elastic cartilage

elastic cartilage Found in the:

o auricle of the ear o the walls of the external auditory canals o auditory (Eustachian) tubes o epiglottis o upper respiratory tract

Mingling of hyaline cartilage and dense connective tissue - Found in intervertebral discs, attachment of certain ligaments, and in pubic symphysis

fibrocartilage

the only cartilage that dont have perichondrium

fibrocartilage

All place where it serves as VERY TOUGH, YET CUSHIONING SUPPORT tissue for bone

fibrocartilage

occur single and often in aligned isogenous aggregates producing type II collagen and other ECM components

fibrocartilage chondrocytes

scarcity of proteoglycans

fibrocartilage is acidophilic

fibrocartilage act as lubricated cushions and shock absorbers preventing damage to adjacent vertebrae from abrasive forces of impacts

INTERVERTEBRAL DISCS OF SPINAL COLUMN

A process where all cartilage forms from embryonic mesenchyme

CHONDROGENESIS

Poor capacity of cartilage for repair or regeneration is due in part to its

AVASCULARITY and LOW METABOLIC RATE

Is the main constituent of the adult skeleton

Bone (or osseous) tissue

provides solid support for the body, protects vital organs (such as cranial and thoracic cavities and medullary cavities) containing bone marrow where blood cells are formed

Bone (or osseous) tissue

Serves as a reservoir of calcium, phosphate and other ions that can be released or stored in a controlled fashion to maintain constant concentrations in body fluids

Bone (or osseous) tissue

is a specialized connective tissue composed of calcified extracellular material, bone matrix and three major cell types

Bone (or osseous) tissue

3 major cells types of bone

osteocytes osteoblast osteoclast

Found in cavities (lacunae) between bone matrix layers (lamellae) with cytoplasmic processes in small canaliculi that extend into the matrix

Osteocytes

Growing cells which synthesize and secrete the organic components of the matrix

Osteoblasts

Bone forming cell

Osteoblasts

Immature cells before turning into osteocytes Has a prominent nucleus

Osteoblasts

Which are giant, multinucleated cells mvolved in removing calcified bone matrix and remodeling bone tissue

Osteoclasts

Bone consuming cell

Osteoclasts

Macrophage of bone

Osteoclasts

Contains the capillaries, fibroblasts and osteoprogenitor stem cells

Mesenchymal regions

internal surface surrounding the marrow cavity

Endosteum

external surface of the bone

Periosteum

Originated from mesenchymal stem cells Produce the organic components of bone matrix, including type I collagen fibers, proteoglycans and matricellular glycoproteins such as osteonectin Are polarized cells with ultrastructural features denoting active protein synthesis and secretion

Osteoblasts

a layer of unique collagen-rich material between osteoblast layer and the pre-existing bone surface

OSTEOID

a vitamin K-dependnet polypeptide, prominent among the noncollagen proteins secreted by osteoblasts

OSTEOCALCIN

release membrane-enclosed by osteoblast rich in alkaline phosphatase and other enzymes which raisies the local concentration of PO4 3− ions - serve as foci for the formation of hydroxyapatite crystals, the first visible step in calcification

MATRIX VESICLES

Most abundant cell in bone

OSTEOCYTES

Enclosed singly within the lacunae spaced throughout the mineralized matrix

OSTEOCYTES

where diffusion of metabolites between osteocytes and blood vessels occurs

CANALICULI

detects mechanical load on the bone as well as stress-or fatigue-induced micro-damage and trigger remedial activity in osteoblasts and osteoclasts

MECHANOSENSORS

paracrine and endocrine that helps regulate bone remodeling

proteins

It maintains the calcified matrix and their death is followed by rapid matrix resorption

OSTEOCYTES

Are very large, motile cells with multiple nuclei that are essential for matrix resorption during bone growth and remodeling

Osteoclasts

For the development it needs 2 polypeptides (produced by osteoblasts):

Macrophage-colony-stimulating factor (M-CSF) Receptor Activator of Nuclear factor B ligand (RANKL)

Areas of bone that undergo resorption. osteoclasts on the bone surface lie within enzymatically etched depression or cavities in the matrix

Resorption lacunae (or Howship lacunae)

the membrane domain that contacts the bone forms a sealing zone that binds the cell tightly to the bone matrix and surrounds an area with many surface projections, called ruffled border

Active osteoclast

Allow the formation of a specialized microenvironment between the osteoclast and the matrix which bone resorption occurs

Circumferential sealing zone

of the dry weight of bone matrix is inorganic materials

About 50%

is the most abundant but bicarbonate, citrate, magnesium, potassium and sodium are also found

Calcium hydroxyapatite

90% but also include small proteoglycans and multi-adhesive glycoproteins such as OSTEONECTIN - Calcium binding proteins, osteocalcin, and the phosphatases release from matrix vesicles promotes calcification of the matrix - Because of its high collagen content, decalcified bone matrix is acidophilic

type 1 collagen

notably osteocalcin and the phosphatases released from cells in matrix vesicles promote calcification of the matrix.

Calcium-binding proteins

External and internal surfaces of all bones are covered by connective tissue of periosteum and endosteum

PERIOSTEUM & ENDOSTEUM

Is organized much like the perichondrium of cartilage with an outer fibrous layer of dense connective tissue, containing mostly bundled type I collagen but also fibroblasts and blood vessels

PERIOSTEUM

penetrate the bone matric and bind periosteum to the bone - Periosteal blood vessels branch and penetrate the bone, carrying metabolities to and from bone cells

Perforating (or Sharpey) fibers

inner layer and more cellular, includes osteoblasts, bone lining cells, and mesenchymal stem cells - play a prominent role in bone growth and repair - proliferate extensively and produce new osteoblasts

OSTEOPROGENITOR CELLS

Internally (inner layer) Very thin endosteum covers small trabeculae of bony matrix that project into marrow cavities Also contains osteoprogenitor cells, osteoblasts and bone lining cells but within sparse delicate matrix of fibers

ENDOSTEUM

Types of bone in Macroscopic/Gross Observation Level

1. Compact/cortical bone 2. Cancellous/ Trabecular bone

Typex of bone in Microscopic level

Lamellar bone Woven bone

Constituting 20% of the total bone mass/ lamellar bone

Cancellous (trabecular) bone

Deeper areas with numerous interconnecting cavities

Cancellous (trabecular) bone

Dense areas near the surface Found mostly in the diaphysis of long bones Also includes parallel lamellae organized as multiple external

Compact (cortical) bone

Represents 80% of the total bone mass/ lamellar bone

Compact (cortical) bone

At the microscopic level both compact & cancellous bone typically show 2 types of organization:

(a) Mature lamellar bone - With matrix existing as a discrete sheets (b) Woven bone - Newly formed with randomly arranged components

With matrix existing as a discrete sheets

Mature lamellar bone

Newly formed with randomly arranged components

Woven bone

outer and innermost areas of compact bone enclose and strengthen the middle region containing vascularized osteons

Lamellae

Most bone in adults, compact or cancellous, is organized as

Lamellar bone

- Bulbous ends - Composed of cancellous bone covered by a thin layer of compact cortical bone

EPIPHYSES

Almost totally dense compact bone with a thin region of cancellous bone on the inner surface around the central marrow cavity

DIAPHYSES

Flat bones that form the calvaria (skullcap) have two layers of compact bone

PLATES

a thicker layer of cancellous bone that separates the plates

DIPLOE

Refers to the complex of concentric lamellae surrounding a central canal that contains small blood vessels, nerves and endosteum It is the one that usually form the compact bone

Osteon (haversian system)

A transverse use by canals in communicating with one another

PERFORATING CANALS (Volkmann canals)

Scattered among the intact osteons are numerous irregularly shaped groups of parallel lamellae

INTERSTITIAL LAMELLAE

Beneath the periosteum

EXTERNAL CIRCUMFERENTIAL LAMELLAE

Around the marrow cavity

INNER CIRCUMFERENTIAL LAMELLAE

Pathway of bone

Lamellae/lamellar

Occurs continuously thoughout life - In compact bone, remodeling resorbs parts of old osteons and produce new ones - In healthy adults, 5%-10% of the bone turns over annually

BONE REMODELING

Is nonlamellar and characterized by random disposition of type I collagen fibers and is the first bone tissue to appear in embryonic development and in fracture repair Is usually temporary and is replaced in adults by lamellar bone, except in some places of the body

Woven Bone

newly calcified

Woven bone

Remodeled from woven bone

Lamellar bone

80% of all lamellar bone

Compact bone

20% of the lamellar bone

Cancellous bone

Irregular and random arrangement of cells. and collagen, lightly calcified

Woven bone

Parallel bundles of collagen in thin layers (lamellae) with regularly spaced cells between; heavily calcified

Lamellar bone

Parallel lamellae or densely packed osteons with interstitial lamellae

Compact bone

Interconnected thin spicules or trabeculae covered by endosteum

Cancellous bone

Bone development occurs by one of two processes:

Intramembranous ossification Endochondral ossification

In which osteoblasts differentiate directly from mesenchyme and begin secreting osteoid Bone generates through membranes By which most flat bones begin to form, takes place within condensed sheets ("membranes") of embryonic mesenchymal tissue

Intramembranous ossification

Preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts which then begin osteoid production

Endochondral ossification

Takes place within hyaline cartilage Shaped as a small version or model of the bone formed Bones are well studied in developing long bones where it consists a sequence of events

Endochondral ossification

Also called epiphyseal plate At the age of 18, bone growth stops ➤ Is responsible for the growth in length of the bone and disappears upon completion of bone development at adulthood

Epiphyseal cartilage

Is composed of typical hyaline cartilage

Zone of reserve (or resting) cartilage

Cartilage cells divide repeatedly, enlarge and secrete more type II collagen and proteoglycans and become organized into columns parallel to the long axis of the bone

Proliferative zone

Chondrocytes undergo mitosis and appear stacked within elongated lacunae

Zone of proliferation

Mature chondrocytes in lacunae swell up. compress matrix and undergo apoptosis closer to the large primary ossification center

Zone of Hypertrophy

Spaces created in the matrix by these events When they are invaded by osteoblasts, osteoclasts and vasculature from the primary center

zone of cartilage calcification

Woven bone is laid down initially by osteoblasts and remodeled into lamellae bone

Zone of ossification

Increases the circumference of a bone by osteoblasts activity at the periosteum and is accompanied by enlargement of the medullary marrow cavity

Appositional bone growth

Raises low blood calcium levels by stimulating osteoclasts and osteocytes to resorb bone matrix and release Ca2+ PTH effect on osteoclast is indirect

Parathyroid hormone (PTH)

Produced within the thyroid gland, can reduce elevated blood calcium levels by opposing the effects of PTH in bone

Calcitonin

Are regions where adjacent bones are capped and held together firmly by other connective tissues

JOINTS

2 types of joints

Diarthroses (freely movable joints) Synarthroses (immovable joints)

Allow very limited or no movement and are subdivided into fibrous and cartilaginous joints, depending on the tissue joining the bones

Synarthroses joints

Major subtypes of Synarthroses:

Synostases Syndesmoses Symphyses

Involve bones linked to other bones and allow essentially no movement In older adults, it unites the skull bone In children and young adults, it is held together by sutures or thin layers of dense connective tissue with osteogenic cells

Synostases

Join bones by dense connective tissue only Ex interosseous ligament of inferior tibiofibular joint & posterior region of sacroiliac joints

Syndesmoses

Join bones by dense connective tissue only Ex interosseous ligament of inferior tibiofibular joint & posterior region of sacroiliac joints

Syndesmoses

Have thick pad of fibrocartilage between thin articular cartilage covering the ends of the bones Ex. intervertebral discs

Symphyses

In a diarthroses ligament and a capsule of dense connective tissue Freely mobile joints Classified as free bone movement

Diarthrosis Joints

In a diarthroses ligament and a capsule of dense connective tissue Freely mobile joints Classified as free bone movement

Diarthrosis Joints

2 specialized cells of diarthrosis joints:

(a) Macrophage-like synovial cells (type A cells) (b) Fibroblastic synovial cells (type B cells)

Derived from blood monocytes and remove wear and tear debris from the synovial fluid Represent approximately 25% of the cells lining the synovium which are important in regulating inflammatory events with diarthrotic joints

(a) Macrophage-like synovial cells (type A cells)

Produce abundant hyaluronan and smaller amounts of proteoglycans Materials is transported by water from the capillaries into the joint cavity to form the synovial fluid

(b) Fibroblastic synovial cells (type B cells)

Cancer originating directly from bone cells. (primary bone tumor) is fairly uncommon (0.5% all cancer deaths) Arise in osteoprogenitor cells The skeleton is often the site of secondary, metastatic tumors however arising when cancer cells move into bones via small blood or lymphatic vessels from malignancies in other organs • Most commonly breast, lung, prostate gland, kidney or thyroid gland Multiple production of bone

Osteosarcoma

Extensive network of osteocvte dendritic processes and other bone cells called "mechanostat" Monitoring mechanical loads within bones and signaling cells to adjust ion levels and maintain the adjacent bone matrix Resistance exercise can produce increased bone density and thickness in affected regions, While lack of exercise (or weightlessness experienced by astronauts) leads to deeased bone density, due in part to the lack of mechanical stimulation of the bone cells

Mechanostat

Common among postmenopausal women because it lacks of estrogen Estrogen is hormone responsible for strengthen bone in women Also common to immobilized patients

Osteoporosis

Characterized by dense, heavy bones ("marble bones") • Osteoclast lack ruffled borders and bone resorption is defective o Defective osteoclasts in most patients with osteopetrosis have mutations in genes for the cell's proton-ATPase pumps or chloride channels Opposite of osteoporosis & a genetic disease Result to overgrowth a thickening of bones, often with obiteracion of the marrow cavities, depressing blood cell formation and causing anemia and the loss of WBC

Osteopetrosis

Refers to a group of related congenital disorders in which the osteoblasts produce deficient amounts of type I collagen or defective type I collagen due to genetic mutations It will lead to a spectrum of disorders, all characterized by significant fragility of the bones The fragility reflects normal collagen, which normally reinforces and adds a degree of resiliency to the mineralized bone matrix

Osteogenesis imperfecta ("Brittle bone disease")

Is a fluorescent molecule that binds newly deposnea oreoramic during mineralization with high affinity and specifically labels new bone under the UV microscope Is has been found that it lowers the rate of bone growth A bone biopsy was performed, bone was sectioned without decalcification and examined Appears that fluorescent lamellae and the distance between the labeled layers is proportional to the rate of bone appositional growth This procedure is of diagnostic importance in such diseases as osteomalacia, in which mineralization is impaired and osteitis fibrosa cystica, in which osteoclast activity results in removal of bone matrix and fibrous degeneration

Antibiotic Tetracycline

Calcium deficiency in children A disease in which the bone matrix, does not calcify normally and the epiphyseal plate an be distorted by the normal strains of bone weight and muscular activity Insufficient calcium in the diet or failure to produce the steroid prohormone vitamin D with important absorption of Calcium oy cens of the small intestine

Rickets

Adults calcium deficiency • Dencient calcification of recently formed and partial decalcification of already calcified matrix

Osteomalacia

Lack of growth hormone during the growing years

Pituitary Dwarfism

Excess growth hormone causing excessive growth of the long bones

Gigantism

A disease in which the bones- mainly the long ones- becomes very thick

Acromegaly

Chronic inflammation of the synovial membrane causes thickening of this connecave ussue and stimulates the macrophages to release collagenases and other hydrolytic enzymes Some enzymes eventually causes destruction of the articular cartilage allowing direct contact o the bones projecting into the joint

Rheumatoid arthritis

Within an intervertebral dises Collagen toss or other degenerative changes in the annulus fibrosus are often accompanied by displacement of the nucleus pulposus Occurs most frequently on the posterior region of the intervertebral disc where there are fewer collagen bundles Affected disc dislocates or shifts slightly from its normal position The pain accompanying a slipped disc may be perceived in areas innervated by the compressed nerve fibers- usually the lower lumbar region

Slipped or herniated disc