Week 2 - Cartilage Flashcards
What makes up articular catilage?
- 65-90% water
- fibres (Type II collagen)
- GAGs
- chondrocytes
Where does the nourishment for articular cartilage come from?
Synovial fluid
(no blood supply)
What element of articular cartilage is responsible for compressive strength?
GAGs
What is an aggrecan?
- where is it located?
Aggrecan = hydrophilic molecule which consists of GAGs (Keratan sulfate, chondroitin sulfate, and hyaluronic acid)
- embedded within the extracellular collagen matrix
What are the three types of cartilage?
Hyaline cartilage
Elastic cartilage
Fibrocartilage
What type of collagen forms elastic cartilage?
Elastin
What type of collagen forms articular cartilage?
Type II collagen
What type of collagen forms fibrocartilage?
Type I collagen
Where is fibrocartilage found in the body?
Meniscus of knee;
Labrum of shoulder and hip
What are tendons?
tissues that cross a joint and join muscle to bone
What type of collagen forms tendons?
Type I and Type II collagen
What are the general functions of cartilage?
- sliding
- shock absorber (ex. intervertebral disk)
- flexible support for soft tissues
- growth of bones
Where is hyaline cartilage found?
ribs trachea/bronchi joint surfaces physis skull sutures
Where is elastic cartilage found?
Epiglottis
Ear/External auditory meatus
Eustachian tube
Where is fibrocartilage found?
meniscus
intervertebral disks
tendinous intersections with muscle
What are the 3 key components of cartilage?
- Perichondrium
- Chondrocytes
- ECM
What are the two layers of perichondrium?
- what are they made of?
Outer: fibrous connective tissue –> contains blood vessels
Inner: chondroblasts –> bone forming cells
What is a small group of chondrocytes called?
Isogenous nest
What is found in the ECM of cartilage?
- Collagen or Elastin
- Proteoglycans
The cartilage matrix is divided up into territorial matrix and interterritorial matrix. What is the difference?
Territorial: directly around each lacunae –>greater negative charge–>acidic sulfated GAGs on PGs
Interterritorial: in space between lacunae–>more collagen fibres here
Why are GAGs hydrophilic?
carboxyl groups and sulfhydral groups in the repeating disaccharide units
What is fibrocartilage made up of?
Dense regular connective tissue & cartilage
- collagen type I fibres
What is a tendon made of?
Dense regular connective tissue (Collagen Type I & fibroblasts)
What is a muscle fascicle made up of?
- list smaller divisions of the muslce fascicle
Fascicle is a bundle of muscle fibres (which are bundles of fibrils, which are made from filaments)
What sarcomeric element contains myosin thick fibres?
“A” band
What sarcomeric element contains only actin without myosin?
“I” band
What is the precursor of collagen?
Procollagen
In what form is collagen secreted?
Tropocollagen (3 polypeptide chains in helical structure)
What happens to tropocollagen after it is secreted?
Aggregates into bundles and fibrils to provide mechanical support.
