Joints, synovial fluid and cartilage Flashcards
What are the three types of joints
Fibrous
Cartilagenous
Synovial
Describe fibrous joints
Not much movement
Strong
Collagen fibres inbetween bones
Where are fibrous joints found
Found in skull (periodontal ligament and cranial sutures
Also interosseous membrane
Describe cartilaginous joints
Cartilage between
Primary or secondary
Describe a primary cartilaginous joint
Only hyaline cartilage – SYNCHONDROSIS
Found on growth plate
Describe a secondary cartilaginous joint
hyaline & fibrocartilage – SYMPHYSIS
Found in intervertebral disc
What are the types of synovial joint
- Hinge, Pivot, Saddle, Plane, Condylar, Ball and socket
What determines joint stability
Shape of articulating surfaces
Fibrous capsule and ligaments
Muscles
Cartilage (in synovial joints)
What is the type of cartilage found in synovial joints
Fibrocartilage
Hyaline cartilage
What does fibrocartilage look like and what is its function in synovial joints
Half moon shaped menisci which make the articulating surfaces fit better (increases movement and stability). They also play a role in shock absorption (because they are made up on fibrocartilage (v strong).
What does hyaline cartilage look like and what is its function in synovial joints
Hyaline cartilage : found In articular surfaces of joints. Also contains collagen but not as densely bound and so it weaker.
What kind of proteins are found in joints
Glycoprotein
Proteoglycans
Glycosaminoglycans
What is a glycoprotein
Glycoproteins (e.g. lubricin): proteins to which oligosaccharide chains are attached, i.e. more a protein than a carbohydrate!
What is a proteoglycan
- Proteoglycans (e.g. aggrecan): proteins that are heavily glycosylated (= a protein core to which one or more GAGs attach), i.e. tend to be more carb than protein!-
What is a Glycosaminoglycans
Glycosaminoglycans or GAGs (e.g. hyaluronic acid): long unbranched polysaccharides, which are highly polar and thus attract water (helps maintain high water content)
What is a chondrocyte
A cartilage cell
What do the chondrocytes look like and what to do they do at the superficial layer of hyaline cartilage
They are flattened and produce collagen and glycoproteins (lubricin)
What do the chondrocytes look like and what to do they do at the transitional/deep layer of hyaline cartilage
They are round and produce proteoglycans (aggrecan)
What % of hyaline cartilage is water and why is this important
> 75% water
Water is incompressible
What 3 A words are used to describe cartilage
Avascular
Aneural
Alymphatic
How does cartilage get its nutrients
The synovial fluids help provide nutrients to the cartilage. . It also helps with lubrication (less friction)
Where is synovial fluid made
It is produced by synoviocytes in the synovial membrane (the synovium)
Describe the synovium
Synoviocytes producing the fluid
Rich capillary network
No epithelial lining
What exchanges at the synovium
Direct exchange of oxygen, carbon dioxide & metabolites between blood & synovial fluid
What are the categories of synoviocyte
Type A
Type B
Describe type A synoviocytes
Look like macrophages
Remove debris from tissue
Contribute to synovial fluid production
Describe type B synoviocytes
Fibroblast like
Main producer of synovial fluid
What does synovial fluid contain
Contains Hyaluronic acid & lubricin
How long does it take to turnover synovial fluid
2 hours (rapid)
What are the types of lubrication at a joint
Boundary
Hydrodynamic
Weeping
What is boundary lubrication
Glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film
Hydrodynamic (like aquaplaning)
What is Hydrodynamic lubrication
Surfaces kept apart by liquid pressure
Viscosity changes with load and velocity of movement
What is weeping lubrication
Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume
What happens to joints in the normal aging process
Viscosity of synovial fluid increases
Slower joint movements Reduced lubrication
Water content of cartilage decreases
Reduced shock absorption
