Shoulder trauma - 119 Flashcards
Name 3 diseases that affect collagen.
Scurvy - Vitamin C deficiency, impaired collagen synthesis.
Osteogenesis imperfecta - mutation in DNA coding for collagen I
Ehler’s Danlos - collagen III mutation, fragile skin, blood vessels, hypermobile joints.
Chondrodysplasias - collagen II mutation, joint and bone deformities.
What are the components of bone? (organic and inorganic)
Organic (40% of bone) = 95% collagen, proteoglycans, non-collagenous proteins.
Inorganic (60%) = calcium hydroxyapatite crystals.
What are the types of bone cell and what do they do?
Osteoblasts - producers. Secrete bone ECM, deposit new layers of matrix on bone surface.
Osteocytes- producers. Osteoblasts that became enclosed in secretory product, now osteocytes. Lie in lacunae.
Osteoclasts - destroyers. Resorb bone in remodelling, develop from monocytes. Live in Howship’s lacunae.
What do PTH and Vitamin D3 both stimulate?
What does RANKL do?
What does OPG do?
Bone resorption.
RANKL - increases resorption
OPG - decreases resorption
What is articular cartilage composed of?
Collagens, proteoglycans, chondrocytes.
What are the characteristics of cartilage?
Avascular, aneural, hypocellular, no lymphatics, no basement membrane.
What are the wet and dry weights of cartilage?
WET: 70% water, 20% collagen, 7% proteoglycans, 2% cells.
DRY: 75% collagens, 22% proteoglycans, 3% other proteins.
What is the function of collagen II?
Tensile strength.
What is the predominant cartilage proteoglycan? How does it work?
Aggrecan.
Provides osmotic resistance necessary for cartilage to resist compressive loads. A very large molecule. Hydrophilic (attracts H2O)
What are the main metalloproteinases and what do they do?
MMPs and ADAMTs. They are proteolytic enzymes that degrade cartilage in health and disease.
