Lecture 14- Cartilage And Bone Flashcards
Name the three types of cartilage
1) fibrocartilage
2) elastic cartilage
3) hyaline cartilage
Is cartilage an example of connective tissue ?
Yes
What type of collagen is mainly found in hyaline cartilage
Type 2 collagen
What type of cartilage is found in fibrocartilage
- collagen 1
What cell type is found in hyaline cartilage ?
Chondrocytes ONLY
Does cartilage contain blood vessels ?
No , they are avascular
Why is hyaline cartilage very resilient?
- because they contain a lot of the ground substance hyaluronic acid , which brings in water into the tissue. Water is non compressible ,
- contain many type 11 collagens too which aid with flexibility.
What is the role of the perichondrial region?
- produces fibroblast precursors which develops into chondroblasts.
What makes up a hyaluronate proteoglycan in cartilage tissue ?
- proteoglycans monomer and hyaluronicn acid.
How many hyaluronate proteoglycan aggregates are there per collagen fibril are there in cartilage compared to loose connective tissue ?
- 100.
- compared to 10.
Where is hyaline cartilage found ?
Pcartilage sin the nose
- articular cartilage of a joints in shoulder , knee , elbows , ankles and wrists
- costal cartilage In ribs
- cartilage in invertebral discs
- larynx
- trachea
What is growth from the periphery called ?
Appositional growth
What is growth from the centre called ?
Interstitial growth
What is the role of hyaline cartilage in trachae ?
- keeps the airway open to prevent collapsing of the trachea when the pressure drops
What type of epithelium lines the trachae ?
Pseudostraified epithelium
Why do people with rheumatoid arthritis have pain ?
- in adults , chondorcytes do not repair once they are damaged.
- so when cartilage is damaged, they cannot be repaired.
- instead fibroblasts lay down scar tissue.
-
What cell type is present in elastic tissue ?
CHONDORCYTES ONLY
What is the main fibre in elastic cartilage ?
Elastic fibres
Where are the 3 places in the body you would find elastic cartilage ?
1) Pinner of the ear ( external ear)
2) Eustachian tube
3) epiglottis
What are the cell types of fibrocartilage ?
1) fibroblasts
2) chondrocytes
What is fibrocartilage a combination of what two tissues ?
1) regular dense connective tissue
2) hyaline cartilage
Is there a perichondrium in fibrocartilage ?
No
What are 3 differ ncs between fibrocartilage and elastic cartilage ?
1) elastic cartilage could contain a perichondrium whereas fibrocartilage cannot.
2) fibrocartilage contains chondrocytes and fibroblasts , whereas elastic cartilage contains chondrocytes only.
3) elastic cartilage is found in the pinna of the ear , Eustachian tube , epiglottis whereas fibrocartilage is found in the intervertebral discs , articular discs in the sternoclavicular and temporomandibular joints , the meniscus in the knee , pubic symphysis
Where is fibrocartilage found ?
Intervertebralmdiscs
- articular joints of the temporomandibular joints , sternoclavicular joints
- the meniscus of the knee
- pubic symphysis
What are the two most common injuries that patients come to the GP with !
1) knee meniscus injuries
2) intervertebral discs
What is the main role of the fibrocartilage ?
1) 1) act as a shock absorber
2) resist shearing forces eg when we jump up and then down - the reason why we don’t break ourselves is because the fibrocartilage found in the places they are found.
What is the cause of rheumatoid arthritis ?
— an autoimmune disease
- there is inflammation in the synovial membrane because antibodies attack the synovial membrane- the tissue that lines the joint.
- joint capsule becomes swollen.
- immune cells number increases which in turn causes damage to the cartilage and bone - causing it to erode.
What is the cause of osteoarthritis?
- narrowing of joint space which causes bone to rub together
- mechanical failure of the articular cartilage
What is articular cartilage ?
- tissue that covers the ends of the bones where they come together to form joints.
- they do not have perichondrium
- avascular
- nourished from synovial fluid
Outline the steps in endochrondral ossification
1) at 6-8 weeks a hyaline cartilage model is formed,
2) Still at 6-8 weeks , a bone collar forms ( which later develops into compact bone)
3) at 8-12 weeks : central ossification centre forms through calcification. Nutrient artery penetrates which provides bone-depleting osteogenic cells.
4) POST NATAL: cartilage forms epiphyseal growth plate. Medulla becomes cancellous bone. Secondary ossification centres form.
4) PRE PUBERTAL : epiphyses ossify.
5) PUBERTY : growth of bone is stimulated by IGF, oestrogen
6) MATURE ADULT : there are no longer epiphyseal plates as they are replaced by bone. Hyaline articular cartilage persists to prevent friction between bones.
What type of cell forms an osteoblasts?
Osteoprogenitor which is a stem cell - often called an osteogenic cell
What are the functions of osteoblasts ?
- cannot be divided
- lays down new bone during skeletal development and re modelling.
Where are oestoblasts found ?
They are usually found in large numbers in the periosteum and the endosteum.
Function of oestoclasts
Huge cells
- they are fused monocytes
- found on the surface of cortical bone ( periosteum ) and on the inner surface of cortical bone being the endosteum.
- reabsorption of existing bone.
How do osteocytes form ?
they are formerOsteoblasts that have been trapped in the matrix they made.
Where are osteocytes located ?
- occupies a small region in the bone called lacuna
- which is contained within calcified matrix of bone
What secretes osteoids??
- osteoblasts
Are osteoclasts found in cortical bone ?
No , they are only found in the periosteum and endosteum.
What are osteons
- they are cylinder structures found in compact bone.
- they contain osteocytes
- connected by cannaniculi which transports blood.
- each osteon contains lamellae of compact mineralised collagen
What is periosteum and endosteum?
- periosteum is the outer surface layer of the compact /cortical bone. Whereas endosteum is found on the inner surface of the cortical / compact bone.
What does an osteon contain ?
- consists of lamellae which are layers of compact matrix that surround a central canal called the Haversian canal.
- the Haversian canal contains the bones blood vessels and nerves.
What is the role of the Volkmans canal ?
- they connect adjacent osteons and connect the blood vessels of the Haversian canals with the periosteum.
