Mass Transport In Tissues (D1)

Question 1

What are some key components of the vertebral disc?

Answer 1

• At the center is the Nucleus Pulposus
• Concentric lines of lamellae circle the nucleus called the anulus
• Endplates on bone tips
• Poor blood supply to cartilage centre due to no intrinsic blood supply

Question 2

What is the equation for Ficks Law

Answer 2

Question 3

What makes up the Intervertebral Discs?

Answer 3

• Water
• GAG (Glycosaminoglycans are large polysaccharides)
• Collagen (Protein)
• Metals (small amounts of sodium, iron, calcium)

Question 4

What are the challenges that come with a poor blood supply like the central parts of the IV disc?

Answer 4

• Poor supply of glucose and nutrients
• Poor removal of products such as lactic acid and CO2

Question 5

What is can be used as a model to replicate our spine

Answer 5

Ox Tail
- Consists of multiple Cartilaginous discs of slowly changing size

Question 6

From the Ox tail, what do we know about the outer anulus of the smallest disc in comparison to the largest disc

Answer 6

• Since blood supply is on the periphery of the discs, the outer anulus (furthest from the centre) for both have the highest levels of cell density.
• The smaller discs have higher cell density than the larger discs
• Increasing density of cells, increases production of lactate, so lactate production increases from larger discs to smaller ones

Question 7

What do we know about GAG content and Water content levels across a single IV disc?
What does this tell us about GAG?

Answer 7

Both Water and GAG content increase as we measure from the outer anulus to the centre. (Similar looking profile)
- Telling us that GAG is hydrophilic

Question 8

What do we know about the Relationship of Collagen, Water and GAG?

Answer 8

• Collagen content profile is inverse of water and GAG, being the lowest at the centre of the disc
• Collagen contains little water and is Hydrophobic

Question 9

What are some major challenges faced by IV disc prophylactic drugs?

Answer 9

• Diffusion time into an intervertebral disc depends largely on the size of the disc and molecule
• Pharmacokinetics (breakdown) times of drugs tend to be much shorter than the diffusion time to act in the disc
• The timing and magnitude of concentrations, geometry and cell densities vary hugely between discs, hard to cater to all!

Question 10

What does this tell us?

Answer 10

The solute is able to diffuse entirely into the smaller C3 disc within 2 hours, while it has only not yet diffused into the majority of the centre of the L3 disc.
- Because it is twice the radius and 8x the volume
- Greater distance, poorer cell density, poorer blood supply