Tendon variation Flashcards
What are the two roles of tendons?
transfer load and energy store
What are the two types of tendon?
Positional and energy storing
What do enrgy storing tendons do?
Stretch and recoil to store and release energy, maximising exercise efficiency.
What are the main energy storing tendons?
Achilles and patellar tendons
What is the primary mechanism by which energy storing tendons can stretch and recoil efficiently?
Sliding between adjacent fascicles
To achieve this, the IFM must be highly specialised to facilitate low stiffness inter-fascicles sliding and elastic recoil
What are mechanical properties needed by energy storing tendons?
Increased extensibility
Elasticity
Fatigue resistance
Compare an energy storing tendon to a positional one
Collagen: Lower total collagen content Type III collagen elevated. Collagen crosslink profile differ Differences at the fibril level Collagen crimp angles are greater Fascicles have smaller diameter Lower levels of collagen turnover
Non-Collagenous components:
Increased total proteoglycans
Increased levels of sulphated GAGs
Higher water content
Higher levels of lubricin and elastin in the IFM
Higher DNA content due to higher cellularity
What kind of tissue is type III collagen abundant in?
tissues that require a high degree of compliance (e.g. skin and blood vessels).
May provide greater extensibility and improved recoil
What effect do collagen crosslink profiles have?
Likely influence fibril stiffness and subsequent local mechanics throughout the tendon hierarchy
Exact influence yet to be determined
What are the differences at fibril level between energy storing and positional tendons and why?
Energy storing fibrils have a lower average fibril diameter. May help increase compliance
Why do energy storing tendons have greater crimp angles?
May provide greater energy storing capacity
What does the low turover of collagen in energy storing cells result in?
Result in extremely long half-life of ~200 years
What effect does water content have on tendon properties
Negatively correlated with tissue stiffness
What effects do higher lubricin and elastin levels in the IFM have in energy storing tendons?
Lubricin probably facilitates inter-fascicular slidin
Elastin enables efficient recoil of the IFM
Compare the mechanical properties of an energy storing tendon to a positional one
Lower elastic modulus compared to positional because positional are required to be relatively inextensible so that inefficiency doesn’t occur
Energy storing must stretch and recoil
