Exam 1 Flashcards
fibroblasts
- in tendon, ligament, skin, bone
- creates mostly type I collagen
chondroblasts
- in cartilage
- produces mostly type II
Osteoblasts
- found in bone
- produces type I collagen and
what forms periarticular connective tissues:
- fibrous proteins: collagen, elastin
- ground substance: glycosaminoglycans (GAG), water, solutes
- cells: fibroblasts, chondrocytes
difference between collagen and elastin?
Collagen triple helix
Elastin: net like, no helix, has more give than collagen
Type I collagen
- thick fibers that elongate little when stretched
- comprise ligaments, tendons, fascia, fibrous joint capsules
Type II collagen
- thinner fibers
- framework for maintaining general shape and consistency of structures
- hyaline cartilage
dense connective tissues
- abundant type I collagen
- limited blood supply
- low PG’s/Elastin/cells so low metabolism
acute trauma happens mostly to which joints?
-joints with longest bones since they form longest external moment arms
chronic trauma
- overuse, damage over time
- instability = abnormal loading
- loss of proteins, GAG, water
joint pathology from aging
- protein/PG replacement slows
- dissicated ligaments/cartilage don’t slide as well
- tendons become less stiff and can’t produce muscle force
- weaker bones (reduced cell differentiation
How to regenerate tendon/ligament
-cell: fibroblast
-Stimulus: tension along lines of stress
EX: ext knee for MCL
how to regenerate cartilage
cell: chondrocyte
Stimulus: load/unload along with gliding
EX:bike for patellofemoral irriation
how to regenerate muscle
cell: myocyte
Stimulus: tension to cause disruption of myofibrils
EX: take it to the point of microtearing
how to regenerate bone
cell: osteocyte
Stimulus: compression or tension
EX: with rod through bone for fracture, walk on it; compression stimulates new bone matrix
enthesis organ
- reduces tensile load on insertion
- confers a mechanical advantage on muscle-tendon unit
- different tissues with different Youn’s moduli gliding along each other cause inappropriate cell stimulation
mechanotransduction
: how mechanical forces cause protein expression
bone has what type of collagen?
type I
cartilage has what type of collagen?
type II
tissue type of joint capsules
- dense irregular
- stretched in all directions so striations not in same direction
tissue type of tendon/ligament
dense regular
-striate in uniform direction
loose connective tissue
does not have as much collagen
collagen is a ___
protein
Scleraxis Protein
- leads to new tendon building blocks
- turned on by amount of load (in its line of stress)
- imperfect restoration
Tissue make up effected by:
- activity
- inactivity
- age
- trauma
example of a planar joint
- facet joints in vertebral columm
- carpals (hamate and triquetrum)
example of a hinge joint
humeroulnar joint at elbow
example of pivot joint
atlas on dens of axis
example of a saddle joint
thumb carpal to metacarpal joint
example of a condyloid joint
carpal MCP joint
diarthrodial joints
- synovial joints
- freely moveable
- joint cavity separates bones
Layers of synovial joint (superficial to deep)
- ligament
- joint capsule
- fat pad
- synovial membrane
- articular cartilage
- synovial fluid
location of nerves in a synovial joint:
- bone
- articular cartilage
- in outer layer of joint capsule
thickness of articular cartilage
1-7 mm
-thicker at weight bearing joints; thickest at the hip
articular cartilage
- to disperse loads
- doesn’t have pericondrium so it is harder to heal
- avascular and aneural (may have some sensory nerves but mostly no pain until cartilage breaks down)
difference of cells in the superficial zone of articular cartilage?
- more cells (chondrocytes)
- smaller
- closer together
tide mark in articular cartilage
on top of the calcified zone
-
nutrition above and below the tidemark
above: synovial fluid
below: vascular supply
what is the first line of defense against loads
articular cartilage
articular carilage extracellular matrix
- fibrillar (protein: collagen (70% of dry weight), elastin)
- interfibrillar (ground substance: PGs)
GAG is mechanism for maintaining articular cartilage__
hydration
-water attaches to it
___ is better at resisting shearing
collagen
more water then ____ premeability
greater
-the less it will resist the compressive force
as GAG contact increases then…
creep stiffness increases
stiffness in shear is directly proportional to__
amount of collagen
relationship of the axis and plane of motion
axis is perpendicular to the plane of motion
close packed
- good congruency
- taut ligaments
- increased stability
- little accessory motion
loose packed
- decreased congruency
- loose ligaments
- max accessory motion
position you do mobilizations
loose packed
joint position you test in
loose packed
creep is a phenomenon of_____
viscoelasticity
slope of the stress/strain curve =
stiffness
young’s modulus
: measure of stiffness of a solid material
toe region is caused by
the uncrimping of collagen
the solid phase of articular cartilage resists…
tension
optimal stimulus for articular cartilage
load/unload with gliding
an osteoarthritic joint is ____ stiff
less
creep
- constant load (stress)
- deformation over time (strain)
- may not be permanent
stress relaxation
- constant position (strain)
- change in stress over time
moment arm
perpendicular distance from axis to line of pull of force
moment arm is 0 if:
- the force pierces the axis
2. the force parallels the axis
first class lever
EF
Axis
IF
-neck extensors
second class lever system
axis EF IF -gastrocnemius -less muscle force required -less motion of the bone -less speed
third class
axis IF EF -bicep brachii -greater muscle force required -more motion at distal end of bone -higher speed
mechanical advantage of 2nd class lever systems
greater than 1
mechanical advantage of 3rd class lever systems
less than one
synarthroses
reinforced by fibrous and cartilaginous connective tissues
-permit slight to no movement
diarthroses
- possess a synovial fluid-filled cavity
- permit moderate to extensive movement
joint capsule
- external fibrous layer
- nerve endings
- internal/synovial membrane
cell membrane
-secretes fluid
capsule external layer
- attaches to periosteum, then bone via sharpey’s fibers
- richly innervated
- joint receptors
ligaments
-thickening of capsule or separate (extra-capsular)
internal joint capsule
-synovial membrane
3-10 cell layers thick
differentiation of connective tissue comes from
mesenchymal cells
connective tissue
- large varience
- dependent on function
dense connective tissue
- few cells
- low proteoglycans and elastin
- type I collagen
- limited blood supply
purpose of carbohydrates in GAG
to attract water
what happens to collagen leaves with degeneration?
they start to separate
purpose of type II collagen
provide a framework for maintaining shape and consistency of the structure
phase 1 protects against
compression by water leaving
phase 2 protects against
tension by collagen
hoop stresses
- tension forces generated from compressive forces
- hoop stresses keep articular cartilage contained during compression
what is most predictable of crack formation?
shearing forces