Clinical Relevance of ECM Fibrous Proteins, GAGs, and Proteoglycans

Ehlers-Danlos

aortic/intestinal rupture, eyeball rupture, increased articular motility (joint luxation)

• shoulder popping outdue to weakened connective tissue and hypermobility of joints.

Scurvy

vitamin C (ascorbic acid) deficiency; co-factor required for collagen synthesis

• bleeding gums/tooth loss

  • teeth anchored by collagen ligment so collagen has rapid turnover but this disease weakens this ability

Osteogenesis imperfecta

defective bone collagen leading to fractures

Marfan Syndrome

mutation in fibrillin gene → detect in elastic fiber ssytem → aortic rupture

which disease has to do with type 1 collagen defect?

osteogenesis imperfecta

what diseases are from collagen biosynthesis failure?

ehlers-danlos, scurvy, osteogenesis imperfecta

Why are GAGs and proteoglycans described as "highly hydrated and viscous"?

They pull water (H₂O) into the tissue, creating a viscous fluid.

What is the clinical basis for taking glucosamine supplements?

Joint lubrication — glucosamine supports GAG production, which pulls water in and keeps synovial fluid viscous.

Why does a joint injury often lead to swelling?

Injury triggers a large influx of fluid into the joint space, which presents as swelling.

What key mechanical property do GAGs/proteoglycans provide that allows for cushioning?

Resistance to compression.

In the "jelly donut" analogy for an intervertebral disc, what makes up the outer ring, and what is it called?

A collagen ring called the annulus fibrosus

What fills the inner region of the intervertebral disc (the "jelly" of the jelly donut), and what is it called?

The nucleus pulposus — full of hydrated sugars, GAGs, and proteoglycans.

What happens in a herniated disc, and why is it painful?

The nucleus pulposus is pushed to one side and presses against spinal nerves, causing pain.

How do GAGs/proteoglycans help form a barrier against bacterial penetration in epithelia?

The epithelial layer secretes a basal lamina — a specialized ECM matrix containing sticky, viscous GAGs/proteoglycans — which forms a protective barrier layer.

Why is the epithelial layer particularly reliant on this GAG/proteoglycan barrier?

It is directly exposed to the outside environment, making it vulnerable to bacterial penetration without this protective layer