The Articular System Flashcards
The articular system is comprised of:
Bone
Cartilage
Synovial Fluid
Synovial Membrane
Highly vascularlized, mineralized connective tissue that is living and constantly changing in response to external stress
Bone
Consists of cells and extracellular matrix
Bone
Compact bone on the shaft of a bone that surrounds the marrow cavity and provides strength
Cortical bone
_______ bone always surrounds cancellous bone (below) but the relative quantity of each type varies among bones and within individual bones according to functional requirements
Cortical
Can only deform 2% before fracture occurs
Compact bone
Dense bone
Compact bone
Spongy Bone
Cancellous Bone
Does not contain osteons, always located in the interior of the bone
Cancellous bone
Facilitates cellular action of adding to or withdrawing from calcium and phosphate reservoir within the body
Cancellous bone
Tough outer connective tissue sheath and its associated blood supply that surrounds bone surface
Periosteum
Hollow, cylindrical space within the diaphysis (shaft) that contains fatty yellow bone marrow and blood vessels
Medullary cavity
The periosteum is attached to underlying bone by perforating fibres – thick bundles of collagen that extend from the periosteum into the bone extracellular matrix known as:
Sharpey’s fibers
Protects the bone, assists in fracture repair, helps nourish bone tissue, serves as an attachment point for ligaments and tendons
Periosteum
Thin membrane that lines the medullary cavity, contains single layer of bone-forming cells and small amount of connective tissue
Endosteum
Mature bone cells, main cells in bone tissue and maintain its daily metabolism
Osteocytes
in the bone matrix: Fibre direction is random in the young but highly-ordered and parallel in the older population and consists mainly of collagen fibre bundles
Organic component
There is a greater loss of the ______ fibres in osteoporosis
transverse fibres
Compression strength and modulus of elasticity is the greatest in bones when the fibres are mainly _______ and lowest when the fibres are mainly _______
transverse
longitudinal
Composes 70% of the bony matrix; made up of inorganic component (55%) and water (15%)
Ground substance
consists of salts and minerals which impregnate the collagen fibres and crystallize to provide tissue hardness and rigidity
Inorganic component (of ground substance)
The remaining 15% of bone; provides the flexibility (distortion tolerance) of the bone
Water
The _________ allows bone to increase in length until adulthood, bone is added on to diaphysis side
epiphyseal plate
__________ cartilage remains between the diaphysis and epiphysis as the epiphyseal growth plate
hyaline
bone can resist _______ load better than a torsional or longitudinal load
compressive
Loss of ______ strength causes the bones to become very brittle and susceptible to fracture
tensile
________ fractures occur when the high energy from a high load can not be dissipated fast enough through a single crack in the bone
comminuted
_______ fracture occurs when the remodeling process is outpaced by the load frequency
fatigue
Bone is laid down where needed and reabsorbed where not needed
Wolff’s Law
When bone is placed under _________ bone tissue becomes stronger through increased deposition of mineral salts and production of collagen fibres by osteoblasts
stress (weight bearing exercise)
Bone loss begins after 30 in females, accelerates greater around 45 as levels of _______ decrease and continues until as much as 30% of the calcium in bone is lost by age 70
estrogen
In males, bone loss typically does not begin until age _______
60
Loss of ______ from bones is one of the problems in osteoporosis
calcium
Brittleness results from a decrease rate of _________
protein synthesis
the two principle effects of aging on bone tissue are:
loss of bone mass and brittleness
What are the functions of bone?
Supports soft tissue
Protects internal organs
Serves as levers for movement
Contains red bone marrow which produces blood cells
Stores mineral salts, calcium, phosphate
Contains yellow bone marrow which stores triglycerides
________ are responsible for building articular cartilage during development and maintaining the integrity of the tissue in adulthood
chondrocytes
provides the structural framework of the tissue giving the tissue its shape and tensile stiffness and therefore provides resistance to tensile loads; it additionally anchors the cartilage to the subchondral bone
collagen fibrils (mainly type II)
Consists of proteoglycans and water
Interfibrillary matrix
Provides resilience, lubrication, elasticity, and resists compression
interfibrillary matrix
metabolism of chondrocytes is dependent upon diffusion of oxygen and nutrients from the synovial fluid and subchondral bone through the tissue matrix and this diffusion is aided by ________ , which create the flow of extracellular fluid in and out of the tissue
joint motion and load
What type of articular cartilage is found over the ends of long bone
Hyaline cartilage
Which type of cartilage affords flexibility and strength
Hyaline
Which type of cartilage provides strength and rigidity
Fibrocartilage
Found in annulus fibrosis of the IV disc, symphysis pubis, knee menisci, TMJ disc
Fibrocartilage
Compression of the articular cartilage tissue forces large volumes of _______ to exit the middle zone towards the superficial zone and into the ________ space; this fluid returns after removal of compression
water
synovial
The only vascularized region of articular cartilage
calcified zone
Articular cartilage has a low capacity for regeneration except in _________ with a delicate balance of synthesis and breakdown
perichondrium
What are the functions of articular cartilage?
Protection: collagen provides tensile strength; matrix provides smoothness and firmness
Reduced Friction: provides a smooth and gliding surface with a very low coefficient of friction
Resistance to Compression and Shear Forces: afforded by the elastic and viscoelastic properties of cartilage
Immobilization of joints leads to atrophy of the articular cartilage and therefore continuous ______ motion is believed to be beneficial to healing
passive
What are the functions of synovial fluid?
Nutrition of articular cartilage, discs, menisci
Lubrication: all apposed surfaces that have movement are lubricated by synovial fluid
Heat dissipation
What are the reactions to injury to the synovium?
Post-traumatic synovitis – increased white blood cells; increased proteins results in decreased viscosity due to fall in concentration of hyaluronate
Hemmorhage effusions
lines the non-articular components of synovial joints, as well as bursae and tendon sheaths
Is absent from intra-articular discs or menisci
synovial membrane
