Exam 1 Flashcards by Austin Gunderson

What are the 4 primary tissue components

Collagen
Elastin
Ground substance
Water

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What’s special about collagen

Continuous metabolic turnover through growth and maturity.

At maturity the fibers become MORE STABLE

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Collagen is made by?

Fibroblasts

They are aligned in the extracellular matrix in a parallel arrangement

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What can collagen do?

Stretch 110%

Increases ligaments size and strength

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What does degeneration in ligaments result in?

Decrease in

Diameter
Density
Number
Mass
Metabolism

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How far can elastin stretch?

150% from original length without breaking

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What is ground substance

Aka Cement Substances

Water consists of 60-70% of total connective tissue content

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What are the 4 main GAGs

Hyaluronic acid
Chondroitin 4- sulfate
Chondroitin-6-Sulfate
Dermatan Sulfate

Glucosamine is found in high concentration within GAGs *

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What is the function of water in collagen

It acts as a powerful lubricant

Also helps maintain a CRITICAL DISTANCE between collagen fibers

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What is tissue biomechanics

The development, maintenance, and re molding of tissue as well as the development of damage and disease

Ability to react to external forces

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What are the types of mechanical forces acting on tissue

Compression
Tension
Shear
Torsion
Bending

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What is compression

When a load produces forces that push the material together

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What is tension

When a structure is stretched longitudinally

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What is shear

Forces acting parallel to each other in opposite directions

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What is torsion

Forces twisting/rotating in opposite directions about the long axis

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What is bending

Combination of tensile and compressive loads

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Compression is almost constantly acting on what……….

The vertebral body and the inter vertebral disc

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What are compression injuries

Bruises
Crushing injuries
Compression fractures
Pinching

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Tension occurs during what kind of movements

Rotational

The annular fibers tend to bear the tensile loads

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What are examples of tension injuries

Sprain/strain injuries
Avulsion fractures
Nerve traction injuries

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What type of bone are most at risk for fracture from shear forces

Cancellous bones

Ex. Femoral condyles and tibial plateaus

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What resist the shear forces in the spine?

The facet joints and the annulus fibrosis

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What are examples of shear injuries

Brain injuries
Tibiofemoral translation such as ACL and PCL
Blisters
Spine injuries

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What elements of the spine resist torsion and fail

Facets
Pars interarticularis
Capsular tears
Tears in the annulus

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Spiral fractures of long bones are an example of ___________________

Torsional load failure

What are the most common responses to mechanical loading of tissues

Deformation Growth and remolding Failure

Deformation is when the object may translate or rotate unless in static equilibrium when results in local shape change True or false

TRUE

What does the extent of deformation depend on

Material properties Size and shape of object Environmental factors Forces

What is stress

The external force trying to deform the material Measure the intensity of the force

What is strain

Magnitude of deformation from applied stress Measure of the degree of deformation

Stress is what is ______ to an object while strain is _______ the object responds

Done, how

In addition to strain in direction of the applied stress there is also strain in an _______________ direction of loading

Orthogonal

What are three other qualities of tissues

Strength Ductility Toughness

What is strength

The maximum stress a tissue can withstand without permanent deformation

What is yield strength

Stress at the yield point of a material beyond which permanent deformation will occur

What is ultimate strength

The maximal stress that a material can withstand prior to the intimidation of failure

What is failure strength

The stress at which the material actually breaks or ruptures

What is ductility

Force per unit of area required to deform a material, REPRESENTED BY THE STEEPNESS OF THE STRESS/STRAIN CURVE

____________ tissues fail at low stress but can withstand large strain

Ductile

_____________ tissues can withstand high stress but fail with relatively low strain

Brittle

What is toughness

The total energy required to cause a material to failure Can be estimated by observing the TOTAL AREA under the stress/strain curve

Bone is

More brittle, very strong. Overall toughness is low

Tendons are

Moderate for both strength and ductility. Overall toughness is HIGH

Ligament is

More pliant, lower strength. Overall toughness MODERATE

Elasticity is....

Ability to return to the original shape when the load is removed

What is yield point

Point at which the applied stress can lead to permanent deformation

What is the plastic region?

The nonlinear response of material after the yield point- some degree of deformation will persist after removal of the stress

What is viscosity

Property of materials to resist load that produce shear or tensile forces Viscous (plastic) stretch= is putty like behavior

Viscoelasticity will show what 3 time dependent loading characteristics

Creep Relaxation Hysteresis

What is creep

Continued deformation over time when constantly loaded

Relaxation is......

Eventual decrease in stress that will occur as fluid is no longer exuded

Hysteresis is...........

Energy loss exhibited by viscoelastic materials when they are subjected to loading and unloading cycles

What is micro-failure

Still elastic in this region, small amount of damage to the tissue Grade one sprain

Yield stress is

The stress when plastic deformation starts

What is macrofailure

The tissue undergoes plastic deformation= grade 2 sprain Ruptures result in a= grade 3 sprain

What is anisotropic

Exhibits distinct mechanical properties when loaded along various axes because its structure differs in the transverse and longitudinal directions

Cortical bone can withstand the most stresses in what order?

Compression>tension>shear Also can tolerate longitudinal loads > transverse loads

Cartilage is __________ tissue

Nonvascular Composed of collagen, chondrocytes and ground substance

Articular cartilage is ________ and subject to _______ and _______

Viscoelastic Creep, relaxation

Interfacial wear of articular cartilage is caused by

Adhesion and abrasion

Fatigue wear of articular cartilage occurs due to

Repetition of high loads over a relatively short period of time or with repetition of low loads over an extended period of time

Articular cartilage has only a __________ capacity for repair and regeneration

Limited

The magnitude of the stress sustained by the articular cartilage is determined by the _____________ and the ________

Total load, how the load is distributed over the articular surface contact area

Any intense stress concentration in the contact area will play a primary role in ___________________

Tissue degeneration

How many discs in the adult body

23 discs

How are the discs named?

Given a numeric name based on the segment ABOVE

What percent of the vertebral column height is attributed to discs?

20-33%

What are the three parts of a intervertebral disc

Nucleus pulposus Annulus fibrosus Cartilaginous end plates

A greater ratio of disc to vertebral body ratio means

Greater spinal segmental mobility

Where is the greatest disc to vertebral body height ratio in the spine

CERVICAL (2:5) Lumbar (1:3) Thoracic (1:5)= is the least ratio

What makes up 70-90% of the Nucleus Pulposus

Water 90% at birth 80% at age 20 70% at old age

Lumbar nuclei fill ____________ of total disc area. They are located more ________ than central

30-50%, posterior

Cervical annulus is ____________ on the lateral borders and only ________________

Minimal, a thin strip in back

How is the tissue arrranged in the annulus fibrosus

Concentric laminated bands, same direction within a band HOWEVER, opposite directions in any two ADJACENT bands

The annulus fibrosus is concentric laminated bands which appear to _________ one another obliquely, forming an angle of ______

Cross, 30 degrees

Annular fibers are firmly attached to what?

Cartilaginous endplates via SHARPEYS FIBERS

What structure narrows from the cervicals to lumbars in the spine?

Posterior Longitudinal Ligament

WHat is the weakest area of the annulus?

POSEROLATERAL ASPECT SAID IT WAS GONNA BE A TQ Most likely spot for disc herniation in the lumbar spine

What supplies the nucleus pulposus with most of its nutrition?

The end plate

The outer portion of the end plate is ______________

Impermeable

Diffusion of nutrients in the end plate occurs in the

Central portion

True or false Blood vessels go directly to the disc?

FALSE!

Where do the annular fibers in the disc get their blood supply from?

Adjacent soft tissues

The nucleus pulposus receives its blood supply from

Vertebral bodies

The intervertebral disc represents a

Avascular and aneural tissue

The disc undergoes

Rapid degernation and has limited self repair

As disc degeneration and osteoarthritis become worse the disc becomes more

Innervated by sensory nerve fibers