joints, synovial fluid and cartillage Flashcards
What are the 3 types of joints
fibrous, synovial and cartilaginous
Describe the structure of fibrous joints
2 bones connected by fibrous connective tissue which is densely packed collagen which makes the joint very rigid
Describe the structure of cartilaginous joint
2 bones connected by cartilage
What type of joint has the most movement
synovial joint
What are examples of fibrous joints
cranial sutures and interosseous membranes
Where are interosseous membranes
In between radius and ulna
In between tibia and fibula
What kind of cartilage is in primary cartilaginous joints
Hyaline
What kind of cartilage is in a secondary cartilaginous joint
Hyaline and fibrocartilage
Where are primary cartilaginous joints seen
In the epiphyseal growth plate of long bones
What is an example of secondary cartilaginous joints
Intervertebral discs - made of fibrocartilage but with hyaline cartilage on both sides of the vertebrae which is in contact with the intervertebral disc
What is another name for primary cartilaginous joint
Synchondrosis
What is another name for a secondary cartilaginous joint
Symphysis
What are common features of a synovial joint
Synovial capsule surrounded by a fibrous capsule made of collagen fibres and a synovial cavity within the capsule lined by synovial membrane which produces synovial fluid
What lines the bones in a synovial joint so that the bones don’t rub directly against each other
Articulate cartilage (hyaline)
Why is the shoulder joint incrogruent (not a good fit)
The glenoid cavity is quite deep while the humeral head is very round so they do not match up great - this makes the joint quite unstable although there is high movement
What prevents dislocation of the shoulder joint
Fibrous capsule and ligaments which provide stability
The rotator cuff muscles also stabilise the joint
What are the attributes of articular cartilage
High water content, impermeable and strong under compression
What makes hyaline cartilage hydrophilic
Presence of glycosaminoglycans in them which are highly polar and therefore attract water into the cartilage
What is the thickness of articular cartilage on average
2-3 mm
Does cartilage have blood, lymphatic or neural supply
No, cartilage is avascular, aneural and alymphatic
What is the name of the synovial fluid
Synovium
What cells in the synovial membrane produces synovium
Synoviocytes
What is required for the synoviocytes to produce synovium efficiently
A rich capillary network and no epithelial lining which allows for direct exchange of nutrients such as O2, CO2 and metabolites between blood and synovial fluid
What is the function of type A synoviocytes
Removing of debris from the synovial cavity and contribute to the production of synovial fluid
What is the function of type B synoviocytes
Main producer of synovial fluid
What are the properties of synovial fluid
It is quite viscous
Hyaluranic acid and lubricin are found in the synovial fluid
The fluid component of the synovial fluid comes from the plasma
Why is synovial fluid used as a lubricant
Reduces friction in the joint and therefore there is less wear
What is fluid film lubrication
The two surfaces are kept completely apart by a layer of fluid
What is weeping lubrication
Some of the interstitial fluid is squeezed out of the cartilage into the synovial cavity to increase the fluid volume
What is the boundary lubrication
There is contact between surfaces but the surfaces are coated in bio lubricants like lipids, hyaluronic acid and lubricin
What are bursae and what is their function
Fluid filled sacs e.g supra-patellar bursa - they cushion the joint
What are fat pads and what do they do
They are filled with adipocytes and help lubricate the joints
What is the effect of ageing on cartilage
Thinning of articular cartilage
Water content of cartilage decreases
The quantity of molecules such as hyaluronic acid which affects the viscosity change
Summary effect - increased stiffness, brittleness, reduced shock absorption and less protection of articular surfaces and increased risk of damage