Bone and Joint Flashcards
What are fibroblasts?
They are connective tissue cells that synthesise the synovial membrane, tendons and ligaments.
What are chondrocytes?
They are connective cells that synthesises and secrets cartilage.
What are osteocytes?
They are connective tissue cells that synthesise and secret bone.
What are the three main molecules the extracellular matrix is composed of?
Collagens, proteoglycans and glycoproteins.
Give 4 examples of proteoglycans.
Aggrecan, Verisican Decorin and Fibromodulin.
Give an example of an glycosaminoglycan (GAG) and two proteoglycans that function as biolubricants at joints.
GAG = Hyaluronan
Proteoglycan = Lubricin and Aggrecan.
What is are Bursa?
A bursae is a sac filled with synovial fluid that lines the synovial membrane and helps with joint movement.
What is Bursitis?
Bursitis is inflammation of the bursa.
What are the two types of synovial cells that are in the synovial fluid. What are they are what is each of their function?
Type A = acts as a macrophage to remove wear-and-tear debris from the synovial fluid.
Type B = has a synthetic function and synthesises hyaluronan and lubricin.
What are the three dominant amino acids present in collagen fibrils?
Glycine, Proline and Hydroxyproline.
Which three collagen types are the major structural collagens?
Collagen types I, II and III.
What collagen type provides tendons their tensile strength.
Type I collagen.
What is cartilage mainly composed of?
Type II collagen, aggrecan and hyaluronan.
Name four members of the Matrix Metalloproteinases (MMP) family
Acrhetypal, Gelatinases, Matrilysins, and Furin-activated MMPs.
What is the function of Matrix Metalloproteinases (MMPs)?
MMPs functions to degrade the proteins in the extracellular matric
Name two proteins that can inactivate Matrix Metalloproteinases (MMPs)?
α2-macroglobulins and tissue inhibitors of metalloproteinases (TIMPs).
Which two cytokines can activate pro-MMPs?
Interleukin-1 (IL1) and Tumour Necrosis Factor (TNF).
What is Osteoarthritis?
Osteoarthritis is a degenerative disease that affects the joints and bones. It occurs as a result of increased ECM degradation relative to synthesis.
What is Rheumatoid arthritis?
It is a disease that affects all connective tissues that results in inflammed joints. It occurs as a result of increased matrix degradation relative to synthesis.
What is Tendinopathy (tendinitis)?
It is a degenerative disease that affects the joints and occurs as a result of increased matrix degradation and synthesis.
What are the major proteins types that degraded in patients with Osteoarthritis?
Proteoglycans.
What is Scelerosteosis & Van Buchem Disease?
It is an autosomal recessive disease characterised by increased bone growth, resistance to bone fracture and excessive height.
It is associated with reduced production of the protein ‘Sclerostin’.
What is the Medullary cavity?
It is the central cavity of bones where the bone marrow is stored - it is the site of blood cell formation.
What are the two types of bone structures?
Cortical bone (compact) and trabecular (spongy).
What is the basic unit of cortical (compact) bone called?
The Haversian System or the ‘Osteon’.
What hormone stimulates bone formation and how?
Calcitonin.
1) an increase in blood [calcium] stimulated the release of calcitonin.
2) Its release reduces calcium uptake in the kidney and stimulates calcium deposition in the bones.
What hormone and vitamin works together to stimulate bone remodelling and calcium release, and how?
The Parathyroid hormone (PTH) and Vitamin D.
1) Low calcium stimulates PTH release, which activated vitamin D.
2) This promotes calcium uptake in the kidney and intestines.
What is the main active form of Vitamin D?
1,25 Hydroxy Vitamin D.
What is the difference between osteoblasts, osteocytes and osteoclasts?
Osteoblasts = synthesizes bone cells (e.g. osteocytes).
Osteocyte = a bone cell.
Osteoclasts = a type of bone cell that reabsorbs breaks down bone tissue.
Which signalling pathway is essential for bone formation?
Wnt/beta-catenin signalling.
How does the inhibition of the Wnt/beta-catenin signalling pathway result in reduced bone formation?
1) Sclerostin binds to LRP and prevents Wnt binding to its receptor.
2) As a result beta-catenin is targeted for degraded and so does not translocate to the nucleus.
3) Consequently, the target genes are not activated and osteoblast formation is reduced.
What is Sclerostin and what is its function?
Sclerostin is a negative regulatory of bone formation - reduced sclerostin results in bone formation.
It functions to inhibit the Wnt/beta-catenin pathway to reduce bone formation.
