40.tissues of MS Flashcards
fmost abundant protein in the body
collagen
T/Fproteoglycans are one class of glycoproteins
TRUEGlycoprotein = polypeptides covalently linked by carbohydratesProteoglycan = one class of glycoproteins, they are a polypeptide that is covalently linked to amino sugars (GAGs)
define stress vs strain
stress= force per unit areastrain= deformation produced in a given direction
what is adaptation of a tissue
ability of the tissue to actively maintain specific properties (such as strength and stiffness) that are required for their function and integrity
properties of all musculoskeletal tissue
contain a small amount of progenitor cellsmechanosensitivitymechanotransductioncellular interconnectedness (except NOT in cartilage)
components of ECM
–collagen–proteoglycans (aggrecan)–elastin/elastic fibers–Misc proteins, proteolipids, glycoproteins (fibronectin)
tensile properties of collagen rich connective tissues are determined by what factors
–intrinsic mechanical properties of collagen type–orientation–packing–diameter of collagen fibrilsex. tendon–parallel and dense collagen, therefore withstand unidirectional tensile loads and high stiffness in that directionarticular cartilage–smaller, sparse, weblike collagen, therefore withstands multidirectional tension and resistance to deformation in several directions
major proteoglycan in the body
glycoprotein–>proteoglycan = AGGRECAN (made up on GAGS–keratin and chondroitin sulfate)massive 100 aggrecan per hyaluronic acid backbone, linked to hyaluronic acid via link protein, high level of hydration and turgidity (critical for compressive properties—ex. articular cartilage)
types of classes of glycosaminoglycans
- glycosaminoglycans–keratan sulfate, heparan sulfate2. galactosaminoglycans–chondroitin sulfate
what is hyaluronic acid
nonpeptideconjugated, nonsulfated glycosaminoglycan
what is the most abundant GAG in the body
chondroitin sulfate
name the non sulfated GAG
hyaluronic acid
where is keratin sulfate most prevalent in
bone and cartilage
most negatively charged GAG
heparan sulfate
characteristics of elastin/elastic fibers in connective tissue
flexibleextensibleresilientinsolublerecoilundergo elastogenesis during reparative phase fun fact: make up majority of Nuchal Ligament
deformation or strain of elastic fibers
70% of their resting lengthmax extension: 220% before losing strength
two forms of bone in the adult:
- cortical—compact, osteonal bone 2. cancellous—spongy, trabecular bone
what type of collagen is the periosteal ECM and bone primarily made up of
type I(articular cartilage is type II)
difference btwn woven and lamellar bone
lamellar bone–highly organized, layered bone, alternating orientationwoven bone–loose, disorganized (seen in initial phases of endochondral ossification either during growth or indirect fracture healing)
mineral content of bone
calcium hydroxy apatite
T/Fbone is least strong under tension
TRUEstrongest under compressionweakest under tension
what is wolff’s law
ability of bone to remodel adaptively in response to a mechanical load
which cell is the primary mechanotransducer in bone
osteocyte
most bone remodeling occurs on what surface
trabecular or cortical surfacesHOWEVER, can still occur WITHIN Haversian system of cortical bone (osteoclasts cutting cones, followed by osteoblasts–direct or primary cortical remodeling)
how fast do osteoclastic cutting cones travel per day
cutting cones progress by 50-100 microns per daydirect bone healing WITHIN Haversian system
what makes up cartilage
- water2. collagen (type II for articular cartilage, type I for fibrocartilage)3. proteoglycan (aggrecan)4. glycoproteins
zones of articular cartilage
3 unmineralized zones—TIDEMARK—1 mineralized zoneI superficial or tangential zone—highest cell density, small flat chondrocytes, orientated with long axis parallel w surfaceII transitional zone; larger rounder chondrocytesIII radiate zone; larger cells arranged perpendicular to surfaceIV calcified zone
collagen and proteoglycan turnover in the adult dog
VERY SLOWcollagen turnover 120 YEARSproteoglycan turnover 300 DAYS
T/FThe low modulus of elasticity of articular cartilage allows it to deform and increase the congruity of opposing articular surfaces
TRUE
fx of tendons
attach muscle to bonetransfer force of muscle to skeleton
fx of ligaments
originate and insert onto bonesjoint stability and constrain joint motion
type of collagen in tendons and ligaments
type I collagen
what does it mean that tendons and ligaments are highly anisotropic
directionally dependenthigh stiffness/strength during TENSIONnegligible stiffness/strength during COMPRESSION
viscoelastic property of tendons and ligaments
rate of loading effects their responsestress relaxation and creep occur during low loading over a long time
what is an entheses
specialized region of tendon or ligament at sites of insertion upon a bonefibrous or fibrocartilaginous (ligaments)ex. Sharpey’s fibers
largest organ in the body
skeletal muscle
contractile unit of a myofibril
sarcomere (overlapping Actin and Myosin)repeating sarcomere–>myofibril–>myofibers–>muscle fibers (endomysium)–>fascicles (perimysium)–>muscle bellies (epimysium)
describe a sarcomere unit
heavy central chain of myosinoverlapping light chains of actinA band = central where actin and myosin overlapZ disc = each side of the sarcomereI band = centered around Z disc , contain only actin
describe muscle contraction physiology
nerve signal–Ach and release of calciumCa bind troponin–>structural change to move tropomyosin away from binding site for myosin on actinglobular head of myosin attaches to actinuses free ATP to drive ratchet life change and sliding of actin along myosin–>shortening of sarcomere, contraction of muscle
two basic types of muscle fibers in skeletal muscle
type 1: slow twitch, rich in mitochondria for sustained contraction of low velocity, low force (oxidative mx)type II: fast twitch, fewer mitochondria, rich in myofibrils; work in transient high force high velocity contractions
T/Ftransfer of force to muscle occurs primarily at the level of the perimysium
TRUEforce transfer occurs primarily at the level of the perimysium which has more densely organized and multilayered collagenous structure compared to the endomysium.
