Joints, Synovial Fluid And Cartilage Flashcards
What are the 3 types of joints?
Fibrous, cartilaginous, synovial
3 examples of fibrous joints?
Cranial sutures, periodontal ligament, interosseus membranes
Types of cartilaginous joints?
Synchondrosis (primary cartilaginous), symphysis (secondary cartilaginous)
Difference between primary and secondary cartilaginous joint?
Primary- only hyaline cartilage
Secondary- hyaline and fibrocartilage
Synovial joints common features?
Synovial cavity, articular cartilage, synovial membrane, fibrous capsule
May also contain- articular discs, ligaments, bursar
Types of synovial joints?
Plane, hinge, pivot, condylar, saddle, ball and socket
How are joints stabilised?
Shape of articulating surfaces, capsule and ligaments, muscles
Types of cartilage in synovial joints?
Hyaline cartilage, fibrocartilage
What are the layers called of articular cartilage?
Superficial/ tangential layer and
Transitional layer
Describe the superficial/ tangential layer of articular cartilage
Flattened chondrocytes that produce collagen and glycoproteins (eg lubricin)
Describe the transitional layer of articular cartilage?
Round chondrocytes that produce proteoglycans such as aggrecan
Does articular cartilage contain water?
Yes it is >75% water
What is the collagen orientation in articular cartilage?
Varys form superficial to deep layers,
Horizontal@ articular surface
Diagonal @ centre
Horizontal-ish @ deep
What is lubricin?
A glycoprotein
What is aggrecan?
A proteoglycans
WHat is hyaluronic acid?
A glycosaminoglycan (GAGs)
Define a glycoprotein
Proteins to which oligosaccharide chains are attached i.e more protein than a carbohydrates e
What is a proteoglycan
Proteins that are heavily glycosylated i.e tend to be more carb than protein
What is a glycosaminoglycan
Long unbranched polysaccharides, which are highly polar and thus attract water
Average thickness of articular cartilage?
2-3mm
Thickness of interphalangral joint?
1mm
Thickness of patella?
5-6mm
What is present in the synovium?
Synoviocytes and synovial fluid,
No epithelial lining
What do synoviocytes produce?
Synovial fluid
What is the function of the synovium?
Direct exchange of O2, CO2 and metabolites between blood and synovial fluid
Describe a Type A synoviocyte?
Look like macrophages,
Remove debris,
Contribution to synovial fluid production
Describe Type B synoviocytes
Fibroblast like,
Main producer of synovial fluid
Composition of synovial fluid?
Viscous fluid,
Hyaluronic acid and lubricin,
Fluid component (from blood plasma)
Function of synovial fluid?
Nutrition of cartilage,
Removal of waste products,
Lubrication
Types of lubrication demonstrated by synovial fluid
Boundary, hydrodynamic, weeping
Boundary lubrication?
Glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film
Hydrodynamic lubrication
Surfaces kept apart by liquid pressure,
Viscosity changes withload and velocity of movement
Weeping lubrication?
Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume
What is the bursae?
A synovial membrane that is fluid filled and reduces friction
How can ageing affect your synovial fluid?
There is increased synovial fluid viscosity:
— causing slower joint movements,
— reduced lubrication
Decreased water content of cartilage:
—reduced shock absorption
