40.tissues of MS

Question 1

fmost abundant protein in the body

Answer 1

collagen

Question 2

T/Fproteoglycans are one class of glycoproteins

Answer 2

TRUEGlycoprotein = polypeptides covalently linked by carbohydratesProteoglycan = one class of glycoproteins, they are a polypeptide that is covalently linked to amino sugars (GAGs)

Question 3

define stress vs strain

Answer 3

stress= force per unit areastrain= deformation produced in a given direction

Question 4

what is adaptation of a tissue

Answer 4

ability of the tissue to actively maintain specific properties (such as strength and stiffness) that are required for their function and integrity

Question 5

properties of all musculoskeletal tissue

Answer 5

contain a small amount of progenitor cellsmechanosensitivitymechanotransductioncellular interconnectedness (except NOT in cartilage)

Question 6

components of ECM

Answer 6

–collagen–proteoglycans (aggrecan)–elastin/elastic fibers–Misc proteins, proteolipids, glycoproteins (fibronectin)

Question 7

tensile properties of collagen rich connective tissues are determined by what factors

Answer 7

–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

Question 8

major proteoglycan in the body

Answer 8

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)

Question 9

types of classes of glycosaminoglycans

Answer 9

1. glycosaminoglycans–keratan sulfate, heparan sulfate2. galactosaminoglycans–chondroitin sulfate

Question 10

what is hyaluronic acid

Answer 10

nonpeptideconjugated, nonsulfated glycosaminoglycan

Question 11

what is the most abundant GAG in the body

Answer 11

chondroitin sulfate

Question 12

name the non sulfated GAG

Answer 12

hyaluronic acid

Question 13

where is keratin sulfate most prevalent in

Answer 13

bone and cartilage

Question 14

most negatively charged GAG

Answer 14

heparan sulfate

Question 15

characteristics of elastin/elastic fibers in connective tissue

Answer 15

flexibleextensibleresilientinsolublerecoilundergo elastogenesis during reparative phase fun fact: make up majority of Nuchal Ligament

Question 16

deformation or strain of elastic fibers

Answer 16

70% of their resting lengthmax extension: 220% before losing strength

Question 17

two forms of bone in the adult:

Answer 17

1. cortical—compact, osteonal bone 2. cancellous—spongy, trabecular bone

Question 18

what type of collagen is the periosteal ECM and bone primarily made up of

Answer 18

type I(articular cartilage is type II)

Question 19

difference btwn woven and lamellar bone

Answer 19

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)

Question 20

mineral content of bone

Answer 20

calcium hydroxy apatite

Question 21

T/Fbone is least strong under tension

Answer 21

TRUEstrongest under compressionweakest under tension

Question 22

what is wolff’s law

Answer 22

ability of bone to remodel adaptively in response to a mechanical load

Question 23

which cell is the primary mechanotransducer in bone

Answer 23

osteocyte

Question 24

most bone remodeling occurs on what surface

Answer 24

trabecular or cortical surfacesHOWEVER, can still occur WITHIN Haversian system of cortical bone (osteoclasts cutting cones, followed by osteoblasts–direct or primary cortical remodeling)

Question 25

how fast do osteoclastic cutting cones travel per day

Answer 25

cutting cones progress by 50-100 microns per daydirect bone healing WITHIN Haversian system

Question 26

what makes up cartilage

Answer 26

1. water2. collagen (type II for articular cartilage, type I for fibrocartilage)3. proteoglycan (aggrecan)4. glycoproteins

Question 27

zones of articular cartilage

Answer 27

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

Question 28

collagen and proteoglycan turnover in the adult dog

Answer 28

VERY SLOWcollagen turnover 120 YEARSproteoglycan turnover 300 DAYS

Question 29

T/FThe low modulus of elasticity of articular cartilage allows it to deform and increase the congruity of opposing articular surfaces

Answer 29

TRUE

Question 30

fx of tendons

Answer 30

attach muscle to bonetransfer force of muscle to skeleton

Question 31

fx of ligaments

Answer 31

originate and insert onto bonesjoint stability and constrain joint motion

Question 32

type of collagen in tendons and ligaments

Answer 32

type I collagen

Question 33

what does it mean that tendons and ligaments are highly anisotropic

Answer 33

directionally dependenthigh stiffness/strength during TENSIONnegligible stiffness/strength during COMPRESSION

Question 34

viscoelastic property of tendons and ligaments

Answer 34

rate of loading effects their responsestress relaxation and creep occur during low loading over a long time

Question 35

what is an entheses

Answer 35

specialized region of tendon or ligament at sites of insertion upon a bonefibrous or fibrocartilaginous (ligaments)ex. Sharpey’s fibers

Question 36

largest organ in the body

Answer 36

skeletal muscle

Question 37

contractile unit of a myofibril

Answer 37

sarcomere (overlapping Actin and Myosin)repeating sarcomere–>myofibril–>myofibers–>muscle fibers (endomysium)–>fascicles (perimysium)–>muscle bellies (epimysium)

Question 38

describe a sarcomere unit

Answer 38

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

Question 39

describe muscle contraction physiology

Answer 39

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

Question 40

two basic types of muscle fibers in skeletal muscle

Answer 40

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

Question 41

T/Ftransfer of force to muscle occurs primarily at the level of the perimysium

Answer 41

TRUEforce transfer occurs primarily at the level of the perimysium which has more densely organized and multilayered collagenous structure compared to the endomysium.