Tendons Exam 3

tendon

connects muscle to bone

ligament

connects bone to bone

Two types of tendons/ligaments

1. positional

2. energy storing

positional tendon type

low strain and low elasticity, responsible for keeping things in place

energy storing tendon type

high strain and high elasticity, responsible for load-bearing

tendon structure

crimp pattern of collagen fibers

hierarchical structure of tendon connective tissue

1. endotenon (inner)

2. epitenon (middle)

3. paratenon (outer)

interfascicular matrix

matrix surrounding fasicles of collagen fibers, surrounded by paratenon

Fascicular matrix components

1. collagen type I

2. collagen type III

3. COMP

4. decorin

Interfascicular matrix components

1. elastin

2. lubricin

3. low levels of collagen

How does hierarchical structure support tendon function?

Allows for interfascicle sliding and collagen fiber crimping and elongation

Biomechanics of tendons and ligaments

1. toe region

2. elastic region

3. yield point

4. plastic region

5. failure point

Tendon cells are…

avascular and acellular relatively

tenocytes

cells in tendons that produce collagen

matrix synthesis

1. tenocytes synthesize collagen molecules and secrete them extracellularly

2. collagen assembly and arrangement occurs extracellularly

Collagen Assembly

1. amino acids join to form alpha chain

2. three alpha chains coil to form triple helix (collagen molecule)

3. link to form tropocollagen or microfibril

4. collagen fiber