PBL 5 Flashcards
What is cartilage?
A type of connective tissue
What is cartilage made of?
A dense network of collagen or elastin, and the associated matrix materials which will provide strength and resilience.
What is the cartilage extracellular matric deposited by?
Chondroblasts, which mature into chondrocytes
Where do the chondrocytes sit in the extracellular matrix?
The spaces - lacunae
What is the perichondrium?
A sheet of connective tissue that covers the surface of most cartilage throughout the body
What are the classifications of cartilage?
Hyaline cartilage, fibrocartilage, and elastic cartilage
What is hyaline cartilage composed of?
Fine type II collagen fibres bound together by a resilient gel like matrix material.
What is hyaline cartilage?
The most abundant yet weakest cartilage
Where is hyaline cartilage found?
All over the body
What is the function of hyaline cartilage?
to provide flexability and support, reducing friction, and absorbing shock. It covers the articular surfaces of joints and provides support to the resp system
What is the function of hyaline cartilage in the foetus?
It forms a temporary skeleton, which is then gradually ossified.
What else does hyaline cartilage form?
The epiphyseal plates in growing long bones
What is fibrocartilage composed of?
Thick bundles of collagen fibres interspersed with chondrocytes in their lacunae
What is fibrocartilage?
The strongest cartilage in the body
What is the function of fibrocartilage?
provides strength and rigidity
Where is fibrocartilage found?
Intervertebral discs, tendon attachment to bones, and the junctions between the flat bones of the pelvis
Does fibrocartilage have a perichondrium?
No
What is elastic cartilage?
Strong and elastic
What is elastic cartilage composed of?
A thread-like network of elastic and collagen fibres interspersed with chondrocytes in their lacunae
What is the function of elastic cartilage?
provides and maintains the shapes of various structures
Where is elastic cartilage found?
The auricle of the ear, the walls of the external auditory meatus, and the epiglottis of the larynx
How is cartilage nourished?
Its avascular so is nourished through diffusion. There is no nerves in cartilage
What is bone?
A specialised type of connective tissue which has a mineralised extracellular component
What is the periosteum?
A layer of connective tissue that surrounds bone
What is the function of periosteum?
To nourish the tissue and provide an interface for attachment of tendons and ligaments
What are the two types of bone?
Compact bone and spongy bone (trabecular or cancellous)
What are the differences between the two types of bone?
depend on the relative amount of solid matter and the number and size of the spaces they contain
What do all bones have?
A superficial thin layer of compact bone around a central mass of spongy bone (except where the spongy bone is replaced by a medullary cavity)
What happens in the medullary cavity and spicules of spongy bone of adult bone?
Blood cells and platelets are formed
What is the function of compact bones?
Provide strength for weight bearing in long bones, designed for rigidity and attachment of muscles and ligaments
Where is most of the compact bone found?
Near the middle of the shaft (body) of the bone, where it has the most risk of buckling
What is the rigidity and elasticity of living bones like?
A little bit of elasticity (flexibility) and great rigidity (hardness)
What are the different shapes of bones?
Long bones, short bones, flat bones, irregular bones and sesamoid bones
What are long bones?
Tubular structures (e.g. humerus and femur)
What are short bones?
Cuboidal structures (e.g. bones of the wrist and ankle)
What are flat bones?
Serve protective functions - consist of two compact bone plates separated by spongy bone (e.g. skull)
What are sesamoid bones?
round or oval bones that develop in tendons
When do bone markings appear?
Wherever tendons, ligaments and fascia are attached or where arteries lie adjacent to or enter bones
How do other bone formations occur?
In relation to the passage of a tendon or to control the type of movement occurring at a joint
What are the 4 main types of bone cells responsible for?
the formation, repair, development and destruction of bone
What are the 4 main types of bone cells?
osteogenic cells, osteoblasts, osteocytes, osteoclasts
What are osteogenic cells?
Unspecialised mesenchymal cells.
where are osteogenic cells found?
Predominantly alongside membranes that surround the bones and the blood vessels in bone canals
What do osteogenic cells do?
The only bone cells that undergo cell divisions with the resulting cells becoming bone producing cells
What is a mesenchymal cell?
A tissue from which most connective tissue is derived
what are osteoblasts?
Bone producing cells
Where are osteoblasts found?
regions of bone formation such as the surface of growing bones or areas undergoing active bone remodelling
What is the function of an osteoblast?
to synthesize and secrete collagen fibres and other organic components.
What are the components synthesized by osteoblasts used for?
To build the extracellular matrix of bone tissue and to initiate calcification
What happens when the matrix is formed by osteoblasts?
the osteoblasts become trapped in their own secretions and eventually are turned into osteocytes
What are osteocytes?
the major cell type found in mature bone
What are osteocytes derived from?
osteoblasts
Where are osteocytes found?
within the matrix of the bone
What is the function of osteocytes?
Maintain the daily metabolism of bone tissue, which includes the exchange of nutrients and waste within the blood
What are osteoclasts?
large cells derived from the fusion of monocytes present within the bone marrow or from other blood producing tissue
Where are osteoclasts present?
in close contact with the bone surface in bone surface resorption bays and are mainly concentrated within the layer of connective tissue on the inside of the bone
What is the function of osteoclasts?
local removal of bone growth and the subsequent remodelling of the bone surface.
What is resorption?
local removal of bone growth and the subsequent remodelling of the bone surface.
Where is resorption commonly seen?
The normal development, maintenance and repair of bone
How do osteoclasts carry out resorption?
They release HCL
What is the organic part of the bone matrix composed of?
Osteoid
What is osteoid produced and secreted by?
Osteoblasts
What is osteoid maintained by?
osteocytes
What is osteoid made up of?
Predominantly type 1 collagen fibres and a small proportion of ground substance
How much of bone is made up of inorganic mineral?
approximately 50%
What is the inorganic mineral in bone called?
Hydroxyapatite
What is hydroxyapatite formed from?
Mineral salts which combine with additional salts on the matrix (calcium and phosphate)
What is the process that forms hydroxyapatite called?
Calcification
what is a joint?
Where two or more bones articulate
What does articulate mean?
Where two or more bones meet
what three categories are joints put into structurally?
Fibrous, cartilaginous and synovial?
What are fibrous joints?
connected by dense connective tissue, have no joint cavity. Most are synarthrotic or amphiarthrotic
What are cartilaginous joints?
Connected by hyaline cartilage and have no joint cavity
What are synovial joints?
Have a synovial, fluid filled cavity that surrounds the articulating bones
what three categories are joints put into functionally?
synarthrosis, amphiarthrosis, diarthrosis
What are synarthrosis joints?
joints that don’t provide any movement
What are amphiarthrosis joints?
Joints that provide only a small degree of movement
What are diarthrosis joints?
Joints that allow free movement
How can joints be classified?
By their structural components, the tissue that holds the bones together, their functions or the degree of movement that they provide
What are the three types of fibrous joints?
suture, gomphosis and syndesmosis
Where are suture joints found?
between the plate bones of the skull
Where are gomphosis joints found?
the tooth junction
What are syndesmosis joints?
two bones are held together by an interosseous ligament. These joints are amphiarthrotic
What does an interosseous ligament consist of?
long collagenous fibres
What are the two types of cartilaginous joints?
Synchondrosis and symphyses
