Joints, Synovial fluid and Cartilage Flashcards
Name the 3 different types of joints:
Structural classification:
-1) Fibrous
- 2) Cartilaginous
- 3) Synovial
(Fibrous = Bone – fibrous connective tissue/ collagen fibres – Bone)
(Cartilaginous = Bone – Cartilage – Bone)
(3 different types
1) Holding the 2 bones is densely packed collagen fibres- strong so difficult to pull the 2 bones apart
2) Cartilaginous- a layer of cartilage between the 2 bones
3) Synovial joint: most mobile joints in the body and found in the limbs )
Name 3 locations in the body where fibrous joints are found:
- Peridontal ligament (teeth)
- Cranial sutures
- Interosseus membranes (between radius and ulna however it doesn’t prevent pronation in the forearm)
What are the 2 types of cartilaginous joints and describe them?:
- Primary cartilaginous: only hyaline cartilage (also called SYNCHONDROSIS)
- Secondary cartilaginous joint: hyaline & fibrocartilage (also called SYMPHYSIS)
(Primary c. joint is found in growing long bones- primary cartilaginous joint- epiphyseal growth plate)
(Secondary c. joint is found in intervertebral disc)
List some common features of synovial joints:
- Synovial cavity (fluid filled)
- Articular cartilage
- Fibrous capsule
- Synovial membrane
MAY ALSO CONTAIN:
-Articular discs
- Ligaments
- Bursae
(Fluid is synovial fluid
2 types of membrane surrounding the synovial cavity
Bursae are fluid filled sacs of membrane that are around joints)
Name the 6 different types of synovial joints:
- Plane
- Hinge
- Pivot
- Condylar (ellipsoid)
- Saddle
- Ball and socket
(IV discs are not synovial joints- they are symphysis, the articular joints are however)
Name some things which contribute to Joint stability:
- Shape of articulating surfaces
- Capsule & Ligaments
- Muscles
(musculature stabilizes the joint)
Name the 2 different types of cartilage found in synovial joints:
Hyaline cartilage and Fibrocartilage
(Blue articular cartilage covering joint surface of tibia (fibrocartilage)
menisci sitting on top of the articular cartilage
Menisci are hyaline cartilage
Densely packed collagen fibres that make up fibrocartilage = strong
Hyaline- also have collagen fibres- hyaline is mechanically weaker than fibrocartilage – rounded cells are chondrocytes)
What is another name for hyaline cartilage?
Articular cartilage
Describe the Superficial/ tangential layer of articular cartilage:
Flattened chondrocytes that produce collagen and glycoproteins (e.g. lubricin)
What do chondrocytes produce?
Collagen and glycoproteins
chondrocytes produce collagen fibres
Describe the Transitional layer of articular cartilage:
Round chondrocytes that produce proteoglycans such as aggrecan
(aggrecan is an enormous molecule and binds water very well)
(-proteoglycans - more carb than protein
-glycoprotein- more protein than carb)
Describe what happens to collagen from superficial to deep layers:
change in collagen orientation from sup to deep layers
what is articular cartilage mostly made up of?
> 75 % water (water = incompressible)
articular cartilage has a v. high concentration of water, water makes cartilage very strong under compression
Articular cartilage: Describe cartilage thickness and forces:
- average: 2-3mm
- interphalangeal joint: 1mm
- Patella: 5-6mm
Cartilage is 3 things, what?
- Avascular (cartilage doesn’t have a blood supply like bone- important, thus synovial fluid is an important means to transport nutrients and waste products)
- Aneural
- Alymphatic
What is synovial fluid produced by?
synovial membrane (synovium)
Describe what the SYNOVIUM is?
- Synoviocytes producing the fluid
- rich capillary network
- No epithelial lining
–> direct exchange of oxygen, co2 and metabolites between blood and synovial fluid
(-same type of tissue also found tendon sheaths
-No epithelial lining thus direct exchange)
What are the 2 types of synoviocytes?
Type A and Type B
Describe type A synoviocytes:
- look like macrophages
- remove debris
- contribute to synovial fluid production
(TYPE A IMPORTANT FOR REMOVING WASTE PRODUCTS)
Describe Type B synoviocytes:
- Fibroblast like
- Main producer of synovial fluid
What is synovial fluid?
Viscous fluid
Hyaluronic acid & lubricin
Fluid component (from blood plasma)
Small volumes (knee joint: 0.5ml)
Rapid turnover (approx 2 hrs)
What are some functions of synovial fluid?
Nutrition of cartilage (articular c., menisci/ discs)
Removal of waste products
Lubrication –> less friction –> less wear
(synovial fluid- main function is for lubrication)
Name the 3 different types of lubrication:
Boundary
Hydrodynamic
Weeping
Describe boundary type of lubrication:
Glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film
Describe Hydrodynamic (like aquaplaning) type of lubrication:
- Surfaces kept apart by liquid pressure
- Viscosity changes with load and velocity of movement
Describe Weeping type of Lubrication:
Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume
(Weeping- synovial fluid is pushed out of cartilage when pressure is applied and into the cavity)
What are BURSAE?
- Synovial membrane
- Fluid filled
- Reduce friction
- Bursitis
(Structures that reduce friction between different tissues at the joint)
Describe what happens with ageing:
VISCOSITY of synovial fluid INCREASES: slower joint movements, reduced lubrication
WATER CONTENT of cartilage DECREASES: reduced shock absorption
Less protection of articular surfaces & increased risk of damage
(less water content in cartilage as a result of ageing)
Describe osteoarthritis:
- Bone spur
- Narrowed disc