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Flashcards in Joint Physiology Deck (35):
1

What is a fibrous joint?

Bones united by a fibrous tissue

2

What is a cartilaginous joint?

bones united by cartilage

3

What is the synovial membrane?

vascular connective tissue with capillary networks and lymphatics that lines the inner aspect of fibrous capsule
contains synovial cells (fibroblasts) which produces the synovial fluid

4

What covers the articular surfaces of bones?

cartilage

5

How do you differentiate between a simple and compound synovial joint?

simple - one pair of articular surfaces
Compound - more than one pair of articular surfaces

6

What is the physiological functions of joints?

structural support
purposeful motion

7

What are the 3 main roles of joints during purposeful motion?

- stress distribution
- confer stability
- joint lubrication

8

What is joint lubrication provided by?

- cartilage interstitial fluid
- Synovium - derived hyaluronic acid (mucin) - a polymer of disaccharides
- Synovium-derived lubrcin - a glycoprotein

9

What helps to confer stability?

shape of articular component
ligaments
synovial fluid

10

What are the functions of synovial fluid?

- lubricates joints
- facilitates joint movements to reduce friction
- helps minimise wear and tear
- aids in nutrition of articular cartilage (avascular)
- supplies chondrocytes with O2 and nutrients and remove CO2 and waste products

11

Give the general characteristics of synovial fluid?

- fills the joint cavity
- continuously replenished
- high viscosity (varies with joint movement)
- other constituents are derived from blood plasma
- contain few cells (mainly mononuclear leucocytes)

12

How does the synovial fluid change during movement in terms of viscosity and elasticity?

Rapid movement is associated with decreased viscosity and increased elasticity

13

What does normal synovial fluid look like?

clear and colourless

14

What happens to the synovial fluid in pathology?

WBC count increased in inflam and sepsis
Turns red in traumatic synovial tap and in haemorrhage arthritis

15

What are the main functions of articular cartilage and why?

low friction lubricated gliding surface to help prevent wear and tear
distributes contact pressure to subchondral bone

16

Name the layers of articular cartilage from the articular surface down.

Superficial zone
Middle zone
Deep zone
Calcified zone

17

In the different zone of articular cartilage, how do the collagen fibres differ?

organization of collagen fibres
relative content of cartilage component

18

What is the articular cartilage made of? Describe it’s properties.

Hyaline cartilage
elastic and has sponge like properties

19

What is the ECM of the articular cartilage made up of?

water 70% (most at top zone)
collagen type 2 20%
proteoglycans 10% (highest conc in middle and deep zone)

20

What happens to the cartilage water, chondroitin and collagen content with age?

Decreases

21

What is the purpose of water in the articular cartilage component, water?

Maintain the resiliency of the tissue and contribute to the nutrition and lubrication system

22

What is the function of collagen in the articular cartilage?

Maintain cartilage architecture
Provides tensile stiffness and strength

23

What is the proteoglycan component made up of?

mainly of glycosaminoglycan e.g. chondroitin sulphate

24

Give the function of having proteoglycans in the cartilage.

Responsible for the compressive properties associated with load bearing

25

What synthesises, organises, degrades and maintains the ECM of articular cartilage?

Chondrocytes

26

The articular cartilage is avascular. How does it receive nutrients etc?

Chondrocytes receive nutrients and O2 via the synovial membrane

27

The rate of degradation is/is not equal to the rate at which it is replaced?

Is - in normal jointa

28

What could change the mechanical properties of cartilage?

changes in the relative amount of water, collagen and proteoglycans

29

If the rate of ECM degradation exceeded the rate of it's synthesis, what would happen?

joint disease

30

What are the catabolic factors relating to cartilage matrix turnover?

Stimulate proteolytic enzymes and inhibit proteoglycan synthesis

31

What are the anabolic factors relating to cartilage matrix turnover?

Stimulate proteoglycan synthesis and counteract effects of IL-1

32

Name the markers of cartilage breakdown?

Increased levels of serum and synovial keratin sulphate
Increased levels of type 2 collagen in synovial fluid

33

What may go wrong in a joint?

- cartilage and synovial composition and function deteriorate leading to wear and tear
- synovial cell proliferation and inflammation
-deposition of salt crystals
- injury and inflammation to periarticular structures

34

What are the effects on the subchondral bone of cartilage deterioration?

- Cyst formation
- Sclerosis (increased density)
- Osetophyte formation (spiky bony formation into joint cavity)

35

What shape are the crystals which cause gout and pseudogout?

Needle shaped uric acid crystals causes gouty arthritis

Rhomboid shaped calcium pyrophosphate crystals causes pseudo-gout