Lecture 3 - Tissues under load 1 Flashcards
List all the types of load
- tension
- compression
- bending
- shear
- torsion
- combined loading
true or false, loading tissues is a negative change
mostly false, there is a healthy level to which tissues should be loaded
true or false, an unloaded tissue is most common
false, unloaded tissues are rare
what type of loading happens when we lock our knees?
torsion
what is the major tensile molecule?
collagen
what is the most common collagen type?
I
how many different types of collagen are there?
42 genes worth, about 30 different types
the collagen types we are talking about have __________ fuctions
structural
what is the common property between all collagen types?
they are formed from a triple helix of alpha chains
list the locations of type I collagen
everywhere bro
- skin, tendons, bone, etc
list the functions of type I collagen
- withstands tensile force
- stability
- protection
list the locations of type II collagen
cartilage and cornea
list the functions of type II collagen
- tensile strength
- cartilage cushioning and support
list the location of type III collagen
Loose connective tissue -> reticular connective tissue
list the functions of type III collagen
- thinner version of type I
- holds together tissue
- structure and movement of components
list the location of type IV collagen
basement membrane (forms a mesh)
list the functions of type IV collagen
- forms a network at the basement membrane
- thin and strong layer that allows diffusion
- selective?
what is a feature that must be present in a collagen type I alpha helix?
coil must be tight in order to resist tensile forces
what are post-translational modifications?
the addition of hydroxyl and sugar groups in order to increase tightness of the collagen type I alpha helix
what micronutrient is essential for post-translational modifications of type I collagen?
vitamin C
which amino acid ensures the collagen type I coil is tight?
Glycine
along with glycine, what are the other common amino acids that form collagen type I?
proline or hydroxyproline
in type 1 collagen synthesis, which step comes after translation of the proteins?
formation of the pro-alpha chains and then post-translational modifications
in type 1 collagen synthesis, which step comes after the post-translational modifications?
pro-alpha chains form a helix with pro-peptides on either end
what do the pro-peptides do?
prevent the premature collagen strand from self assembling while in the cell
in type 1 collagen synthesis, which step comes after helix formation?
collagen moves out of the cell and the pro-peptides are cleaved off
in type 1 collagen synthesis, which step comes after pro-peptide cleavage?
cross-linking (covalent bonding) between adjacent collagen strands and self assembly occurs.
in type 1 collagen synthesis, which step comes after cross-linking and self-assembly?
formation of a fibril and eventually, a bundle of fibrils will make a collagen fibre.
how does puberty affect bone growth?
increases in sex hormone, growth hormone and thyroid hormones rapidly increase osteoblast activity and ECM synthesis
how does our final height occur?
the bones synthesis outpaces the growth plate cartilage growth, and the growth plate closes, leaving the epiphyseal line
what are the two major clinical implications involving growth plate disruption?
- slipped capital femoris epiphysis SCFE (slipped growth plate)
- precocious puberty
what kind of a final height does precocious puberty lead to?
a lower final height, as the bone synthesis outpaces cartilage far earlier than it should.
what are the features of SCFE?
- high prevalence in NZ
- common in teens
- associated with increased weight, family history and metabolic disorders
- generally doesn’t heal
how does a bone grow in length?
epiphyseal growth plates
how does a bone grow in thickness?
appositional growth
