Joints, Synovial Fluid and Cartilage Flashcards
What different types of joint exist?
Fibrous
Cartilaginous
Synovial
What connects bone in fibrous joints?
Collagen fibres (dense fibrous connective tissue)
Has a high tensile strength making it hard to pull the bones apart
What connects bone in cartilaginous joints?
Cartilage
Give some examples of a fibrous joint (3)
Cranial sutures
Interosseous membranes
Periodontal ligaments (teeth)
What types of cartilaginous joints exist and give some examples
Primary joint - hyaline
Secondary joint - more in the axis
What is the function of a synovial membrane?
To produce synovial fluid and form the synovial cavity
What surrounds the synovial membrane?
Fibrous capsule
What are the different types of synovial joint?
Planar Condylar Hinge Saddle Pivot Ball and Socket
How can joint stability be worked out?
Shape of articulating surfaces
Capsule and ligaments holding in place
Muscles
What types of cartilage are there?
Hyaline cartilage
Fibrocartilage
What cartilages are there in the knee joint?
Meniscus - fibrous cartilage
Hyaline cartilage on kneecap
Explain the layers in articular (hyaline) cartilage
Superficial/tangential layer - flattened chondrocytes that produce collagen and glycoproteins
Transitional layer - round chondrocytes that produce proteoglycans such as aggrecan
Change in collagen orientation from superficial to deep layers
>75% water
Glycoproteins like lubricin act as lubricators of the joint
What does cartilage lack?
Blood supply
Nervous supply
Lymphatic drainage
Avascular
Aneural
Alymphatic
What is synovium?
Lines the inner of the capsule of the synovial joint
Made up of synoviocytes which produce the fluid
Has a rich capillary network and no epithelial lining
There is a direct exchange of oxygen, carbon dioxide and metabolites between blood and synovial fluid
What types of synoviocytes exist and what are their functions?
Type A - look like macrophages, remove debris
Type B - production of synovial fluid
What are the characteristics of synovial fluid?
Viscous fluid Hyaluronic acid and lubricin Fluid component (from blood plasma) Small volumes Rapid turnover
What are the functions of the synovial fluid?
Nutrition of cartilage (articular cartilage/minisci)
Removal of waste products
Lubrication causing there to be less friction and therefore less wear to the joint
What elements are there to the lubrication of a synovial joint?
Boundary - glycoproteins such a lubricin bind to receptors on the articular surfaces to form a thin film
Hydrodynamic - surfaces are kept apart by liquid pressure. Viscosity changes with load and the velocity of movement
Weeping - fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume
How is lubrication measured?
Co-efficient of friction
What are bursae?
Fluid filled synovial membrane sacs which surround joints which reduce friction
What happens to synovial joints during the ageing process?
Viscosity of synovial fluid increases due to slower joint movements and reduced lubrication
The water content of cartilage decreases causing reduced shock absorption
Less protection of articular surfaces and increased risk of damage
