ANATOMY (Cartilage and Bone) Flashcards
Connective tissue fibers:
- Collagenous fibers (20 types)
- Reticular fibers
- Elastic fibers
-each connective tissue will have 3 fibers
*produced inside the fibroblasts
Collagen fibers:
-most common
-more than 20 types
-fibril forming (Type I, II, III, V, XI)
-fibril anchoring (Type IX, XII, XIV)
-anchoring fibril forming (Type VII)
-networking forming (Type IV)
Reticular fibers:
-fibril forming collagen (Type III)
-singular collagen fiber
Elastic fibers:
-stretchable (elastin and fibrillin)
Fascia:
-loose irregular connective tissue
Aponeurosis:
-dense irregular connective tissue
*when need more strength
Tendons and ligaments:
-dense regular connective tissues
-runs in ONE direction
-prevents pulling
Cartilage:
-pliable and firm matrix
-considerable tensile strength
Ex. trachea: use cartilage to maintain the shape and keep it open
Properties of cartilage:
-avascular: no blood (no bleeding)
-alymphatic: no lymph
-aneural: no nerves (no pain)
Cartilage cells:
-chondroblasts
-chondrocytes
Chondroblasts:
-located at periphery of growing cartilage
-oval basophilic cell located in a lucuna
-dividing cell and forms matrix
Chondrocytes:
-elongated to spherical cell
-glycogen and lipid droplets in older chondrocytes
-fill lacunae in living state, but have artifactual space in fixed tissue
Cartilage matrix:
-ground amorphous substances (GAGs) and fibers
-mainly type II collagen fibers (Type I collagen in fibrocartilage)
-proteoglycans
-aggrecan
Proteoglycans:
-bind to collagen to create sieves
Aggrecan:
-formed by binding of proteoglycans to hyaluronic acid
>role in transporting water and electrolytes
GAGs:
-7 types
-non-sulfated GAG (hyaluronic acid: present in cartilage)
-sulfated GAGs (3 present in cartilage)
Perichondrium:
- Inner cellular layer (chondrogenic)
- Outer fibrous layer
*surrounds cartilage (except on articular surface)
Classification of cartilage:
-based on type of fibers in matrix
>hyaline cartilage
>elastic cartilage
>fibrocartilage
Hyaline cartilage:
-firm gel with type II collagen fibers
>have some refractive index as ground substance, so NOT visible
-periphery: small chondrocytes
-deep part: large and polyhedral chondrocytes
-sometimes 2,4 or more chondrocytes per lacuna
Hyaline cartilage location:
-everywhere in body
-80-90%
-cover articulate service of bone or embedded within tissues (ex. trachea)
Small chondrocytes: hyaline cartilage
-in elliptical lacunae running parallel to surface
Elastic cartilage:
-located where elasticity and rigidity are needed
-only few elastic fibers near perichondrium
-dense network of elastic fibers within deeper part
-greater variation in size of lacunae than hyaline cartilage
Elastic cartilage location:
*purpose to make it more flexible
-ear
-epiglottis
Fibrocartilage:
-least frequent occurrence
-type I collagen fibers are present in the matrix (visible with routine stains)
-rows of small lacunae with chondrocytes parallel to collagen bundles
-amorphous matrix close to lacunae
Fibrocartilage lacks:
-cellular chondrogenic layer of perichondrium
Fibrocartilage location:
-between a tendon and a cartilage
Ex. vertebral disks and stifle joint
Development of cartilage:
-embryological origin from mesenchymal cells
-cell (chondroblasts) cluster as center of chondrification
-secrete amorphous substance and Type II collagen (increased matrix)
Increased matrix:
-leads to isolation of chondrocytes
During development growth of cartilage can occur by:
-interstitial growth
-appositional growth
Nutrition of cartilage:
-avascular: nutrition by diffusion
>from capillaries outside the perichondrium
>from synovial fluid
>vascular channels penetrate if cartilage is thicker than 3mm
Bone:
-dynamic tissue (constant renewal and remodeling)
-vascular
-contain bone marrow in medullary
Bone cells and fibers:
-embedded in hard unbending mineralized matrix
Bone cells:
-osteoblasts
-osteocyte
-osteoclast
Osteoblast:
-active formation and mineralization of matrix
-deposits osteoid (collagen I and proteoglycans)
-located near surfaces (flattened to columnar cell)
-basally located nucleus
-basophilic cytoplasm (prominent rER and golgi)
Mineralization:
- Secretory vesicles in osteoblasts
- Released matrix vesicles and collagen fibers
- Early mineralization around vesicles
- Matrix becoming confluent
Osteoblasts to osteocytes:
-osteoblasts surround themselves by osteoid and change to osteocytes
Osteocyte:
-principal cell in mature bone
-essential for preserving bone structure
-lesser rER and golgi than osteoblast
-more lysosomes
-resides in lacuna and extend process through canaliculi
-removes and replaces perilacunar bone (up to 1microm meter)
Osteoclasts:
-large (40-100 micrometer)
-multinucleated (15-30)
-on surface of bone
-resorb bone
-ruffled borders in activated cells (ie. Infoldings)
-secrete acid and lysosomal enzymes
Resorb bone: osteoclasts:
-create resorption bays: Howship lacunae
Bone matrix:
-osteoid
-collagen fibers course spirally in each lamella of osteon
-osteoid mineralization: store house of calcium and phosphorous
Osteoid: bone matrix
-type I collagen and ground substance
Osteoid mineralization
-by deposition of needle-like hydroxyapatite crystals between collagen fibers
>are mobilized when needed
Macroscopic structure of bone:
-epiphyses
-diaphysis
-medullary cavity
-physis and metaphysis
Epiphyses:
-at both extremities
-spongy bone covered by articular cartilage
Diaphysis:
-shaft of the bone
-compact bone containing a medullary cavity
-covered by periosteum and lined by endosteum
Medullary cavity:
-young animals: filled with red bone marrow
-adults: yellow bone marrow
Physis and metaphysis:
-hyaline cartilage
-growth plate
-separates the epiphysis and diaphysis in growing animals
Microscopic structure of bone:
-decalcified bone (ground preparation)
-osteons
-central and perforating canals
-periosteum
Osteons:
-central (haversian)canal
-concentric or haversian lamellae
-lacunae located between concentric lamellae
-interstitial lamellae
-outer and inner circumferential lamellae
-perforating (Volkman’s canal)
Periosteum:
-anchored to outer circumferential and interstitial lamellae by perforating fibers
-inner osteogenic layer
-outer fibrous layer
Inner osteogenic layer: periosteum
-more prominent in young
Outer fibrous layer (periosteum)
-dense
-irregular connective tissue
Bone differences from cartilage:
-presence of canalicular system
-direct vascular supply
Structural and functional characteristics of bone:
-unique lacunar-canalicular system for nutrition
-canaliculi travel from one lacuna to another and to bone surface to open in connective tissue close to capillaries
-no osteocyte more than 100 micrometre away from a capillary
Cartilage take away:
-bendable but firm
-no bleeding
-no pain
-contains perichondrium, chondroblasts, chondrocytes in lacunae and matrix
-three types: hyaline, elastic and fibrocartilage
Bone take away:
-hard and vascular
-dynamic tissue (osteoid and minerals)
-contains osteoblasts, osteocytes and osteoclasts
-compact bone
Compact bone take away:
-arranged in osteons, interstitial and circumferential lamellae
-lined by periosteum and endosteum
