Lecture 3 - Tissues under load 1

Question 1

List all the types of load

Answer 1

• tension
• compression
• bending
• shear
• torsion
• combined loading

Question 2

true or false, loading tissues is a negative change

Answer 2

mostly false, there is a healthy level to which tissues should be loaded

Question 3

true or false, an unloaded tissue is most common

Answer 3

false, unloaded tissues are rare

Question 4

what type of loading happens when we lock our knees?

Answer 4

torsion

Question 5

what is the major tensile molecule?

Answer 5

collagen

Question 6

what is the most common collagen type?

Answer 6

I

Question 7

how many different types of collagen are there?

Answer 7

42 genes worth, about 30 different types

Question 8

the collagen types we are talking about have __________ fuctions

Answer 8

structural

Question 9

what is the common property between all collagen types?

Answer 9

they are formed from a triple helix of alpha chains

Question 10

list the locations of type I collagen

Answer 10

everywhere bro
- skin, tendons, bone, etc

Question 11

list the functions of type I collagen

Answer 11

• withstands tensile force
• stability
• protection

Question 12

list the locations of type II collagen

Answer 12

cartilage and cornea

Question 13

list the functions of type II collagen

Answer 13

• tensile strength
• cartilage cushioning and support

Question 14

list the location of type III collagen

Answer 14

Loose connective tissue -> reticular connective tissue

Question 15

list the functions of type III collagen

Answer 15

• thinner version of type I
• holds together tissue
• structure and movement of components

Question 16

list the location of type IV collagen

Answer 16

basement membrane (forms a mesh)

Question 17

list the functions of type IV collagen

Answer 17

• forms a network at the basement membrane
• thin and strong layer that allows diffusion
• selective?

Question 18

what is a feature that must be present in a collagen type I alpha helix?

Answer 18

coil must be tight in order to resist tensile forces

Question 19

what are post-translational modifications?

Answer 19

the addition of hydroxyl and sugar groups in order to increase tightness of the collagen type I alpha helix

Question 20

what micronutrient is essential for post-translational modifications of type I collagen?

Answer 20

vitamin C

Question 21

which amino acid ensures the collagen type I coil is tight?

Answer 21

Glycine

Question 22

along with glycine, what are the other common amino acids that form collagen type I?

Answer 22

proline or hydroxyproline

Question 23

in type 1 collagen synthesis, which step comes after translation of the proteins?

Answer 23

formation of the pro-alpha chains and then post-translational modifications

Question 24

in type 1 collagen synthesis, which step comes after the post-translational modifications?

Answer 24

pro-alpha chains form a helix with pro-peptides on either end

Question 25

what do the pro-peptides do?

Answer 25

prevent the premature collagen strand from self assembling while in the cell

Question 26

in type 1 collagen synthesis, which step comes after helix formation?

Answer 26

collagen moves out of the cell and the pro-peptides are cleaved off

Question 27

in type 1 collagen synthesis, which step comes after pro-peptide cleavage?

Answer 27

cross-linking (covalent bonding) between adjacent collagen strands and self assembly occurs.

Question 28

in type 1 collagen synthesis, which step comes after cross-linking and self-assembly?

Answer 28

formation of a fibril and eventually, a bundle of fibrils will make a collagen fibre.

Question 29

how does puberty affect bone growth?

Answer 29

increases in sex hormone, growth hormone and thyroid hormones rapidly increase osteoblast activity and ECM synthesis

Question 30

how does our final height occur?

Answer 30

the bones synthesis outpaces the growth plate cartilage growth, and the growth plate closes, leaving the epiphyseal line

Question 31

what are the two major clinical implications involving growth plate disruption?

Answer 31

- slipped capital femoris epiphysis SCFE (slipped growth plate) - precocious puberty

Question 32

what kind of a final height does precocious puberty lead to?

Answer 32

a lower final height, as the bone synthesis outpaces cartilage far earlier than it should.

Question 33

what are the features of SCFE?

Answer 33

- high prevalence in NZ - common in teens - associated with increased weight, family history and metabolic disorders - generally doesn't heal

Question 34

how does a bone grow in length?

Answer 34

epiphyseal growth plates

Question 35

how does a bone grow in thickness?

Answer 35

appositional growth