Physiology of Joints Flashcards

1
Q

What are the three types of joints?

A
  1. Synovial
  2. Fibrous
  3. Cartilaginous
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2
Q

Within a synovial joint, what is the inner aspect of the fibrous capsule lined by?

A

Synovial membrane

(composed of vascular connective tissue with capillaries and lymphatics)

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3
Q

What type of cells are synovial cells and what is thier function?

A

Fibroblasts

They produce synovial fluid

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4
Q

What is a simple synovial joint?

A

A synovial joint with one pair of articular surfaces

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5
Q

What is a compond synovial joint?

A

A synovial joint with more than one pair of articular surfaces

(e.g. the elbow)

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6
Q

Joint lubrication is achieved by which three things?

A
  1. Interstitial fluid - from cartilage
  2. Hyaluronic acid (mucin) - derived from the synovium
  3. Lubricin (a glycoprotein) - derived from the synovium
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7
Q

Why does synovial fluid have a high viscosity?

A

Hyaluronic acid (mucin)

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8
Q

The synovial fluid is a constant pool.

True or false?

A

False

The synovial fluid is continously removed and replenished via the synovial membrane

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9
Q

Which two properties of synovial fluid change during movement?

A
  1. Elasticity
  2. Viscosity

e.g. during rapid movement, elasticity increases and viscosity decreases

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10
Q

Describe normal synovial fluid properties

A
  • Normally around 3.5ml present (in knee)
  • Clear and colourless
  • <200 WBCs
  • High viscosity
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11
Q

If synovial fluid is opaque what does this suggest?

A

The synovial fluid is septic

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12
Q

High white cell counts in the synovial fluid may suggest which two things?

A
  1. There is an inflammatory process (e.g. arthritis)
  2. The synovial fluid has become septic (e.g. infective arthritis)
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13
Q

Synovial joints are known by which other name?

A

Diarthrosis

Which means two articulations.

Arthritis - inflammation of articulation

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14
Q

What is the main purpose(s) of articular cartilage?

A
  • Provides a smooth surface with low friction to prevent wear and tear
  • Distributes contact pressure over a larger surface area
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15
Q

Hyaline cartilage, the cartilage type usually associated with articulation, is composed mainly of which three components?

A
  1. Water
  2. Type II collagen
  3. Proteoglycans
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16
Q

The extracellular matrix of the cartilage comprised what percentage of total cartilage volume?

A

98%

17
Q

Where does the articular cartilage receive nutrients and O2 from?

A

Synovial fluid

(Articular cartilage is avascular - nutrients and O2 diffuse from the synovial fluid into the extracellualr matrix, and chondrocytes)

18
Q

Which catabolic factors may chondrocytes secrete to break down the extracellular matrix?

A
  • Tumour necrosis factor (TNF)-a
  • Interleukin (IL)-1

These prevent proteoglycan synthesis

19
Q

Which anabolic factors may chondrocytes secrete in order to build up the extracellualr matrix?

A
  • Tumour growth factor (TGF)-β
  • Insulin-like growth factor (IGF)-1

These cause proteoglycan synthesis

20
Q

Increased levels of which two things suggest cartilage breakdown?

A
  1. Serum and synovial keratin sulphate
  2. Type II collagen in synovial fluid

Can give clues in diagnosis and/or act as seritity markers for osteoarthritis or rheumatoid arthritis

21
Q

In simple terms, what gives rise to rheumatolid arthritis?

A

The proliferation and inflammation of synovial cells

22
Q

An osteoarthritis knee may show which distinctive physical and histological features?

A
  • Thickened capsule
  • Hypertrophied synovial membrane
  • Fibrillated articular cartilage
  • Cyst formation
  • Osteophyte formation (bony projections from joint margins)
  • Sclerosis in subchondral bone
23
Q

Goutry arthritis is caused by a deposition of what?

A

Uric acid crystals

24
Q

Pseudo-gout is caused by deposition of what?

A

Calcium pyrophosphate crystals

(rhomboid shaped)