phase 1 week 5 Flashcards
What types of bone are there?
long bone short bone irregular bone flat bone sesamoid bone
give an example of a long bone
humerus
give an example of a short bone
carpal bone
give an example of an irregular bone
vertebra
give an example of a flat bone
sternum
give an example of a sesamoid bone
patella
Describe the diaphysis of a bone
main shaft-like portion
hollow and cylindrical shape with thick compact bone on the outside
strong but not too heavy
describe the epiphysis of a bone
both ends of a long bone
bulbous shape which provides space for muscle attachment
red marrow fills the spaces of cancellous bone
describe the metaphysis of a bone
the region where the epiphysis and diaphysis meet
describe the periosteum
dense, white, fibrous membrane
covers bone except for joint surfaces
periosteum fibres penetrate the underlying bone
tendon fibres and periosteum fibres interlace to attach muscle to bone
contains bone remodelling cells and blood vessels
Describe articular cartilage
thin layer of hyaline cartilage that covers the articular surfaces of bones
resilient material that cushions jolts and blows
describe the medullary cavity
hollow space in diaphysis of long bone.
in adults filled with yellow marrow
Describe the endosteum
thin, fibrous membrane that lines the medullary cavities and spaces of cancellous bone
contains bone cells and their precursors
Describe compact bone
cylindrical-shaped osteons or haversian systems
each osteon surrounds a canal which runs longitudinally through the bone
Describe cancellous bone
no osteons
tiny needle-like branches called trabeculae
nutrients and waste products diffuse via tiny canaliculi that extend to the surface of the very thin bony branches
Describe osteoclasts
large cells with many nuclei
share lineage with blood cells (macrophages)
Precursors circulate in blood and bone marrow
When RANK-ligand (from osteoblasts) binds with RANK receptors - mature osteoclast form from fusion of progenitor cells
osteoclasts resorb bone
release acids and enzymes
then undergo apoptosis
What is OPG?
osteoprotogerin
binds to RANK-ligand so can regulate osteoclast activity
Describe osteoblasts
cuboidal and columnar shape with central nucleus
found on bone surface
from mesenchymal stem cells
osteoblasts make proteins to form the organic matrix of the bone and regulate mineralisation
Receptors for vitamin D, oestrogen and parathyroid hormone
secrete RANK-ligand to activate osteoclasts
can differentiate into osteocytes, lining cells or undergo apoptosis
Describe osteocytes
long branches that allow them to contact each other and the lining cells at the bone surface
sense mechanical strain
secrete growth factors to activate lining cells or osteoblasts
Describe lining cells
flat and pancake-shaped
responsible for immediate release of calcium
Protect bone from chemicals that dissolve crystals
receptors for hormoes and factors that effect bone remodelling
What are BMPs?
bone morphogenetic proteins
produced in bone or bone marrow
bind to BMP receptors on mesenchymal cells
cells produce cbfa1 - a transcription factor
cells mature into mature osteoblasts
Describe IGFs in regards to bone
Insulin-like growth factors
produced by osteoblastic cells in response to parathyroid hormone, oestrogen or BMPs
released from matrix during bone remodelling and stimulate osteoblastic cell replication
Describe RANK-ligand
a cytokine that is produced in response to systemic hormones such as 1,25dihydroxyvitaminD3 and other cytokines such as IL6
Induces osteoclast development
What hormones increase bone resorption?
parathyroid hormone
glucocorticoids
thyroid hormone
vitamin D metabolites
What hormones decrease bone resorption
calcitonin
gonadal steroids
what hormones increase bone formation?
growth hormone
vitamin D metabolites
gonodal steroids
What hormones decrease bone formation?
glucocorticoids
what are the main type of inorganic salts found in bone?
hydroxyapatite crytals
What is the organic matric of bone composed of?
collagenous fibres and “ground substance”
name features of a synovial joint
articular cartilage
synovial cavity
synovial membrane
joint capsule
what are the two names for the three kinds of joints?
synarthroses (fibrous)
ampiarthroses (cartilaginous)
diarthrosis (synovial)
Describe synarthrosis movement
immovable
describe ampiarthoses movement
slightly moverable
Describe diarthrosis movement
freely moveable
What types of fibrous joints are there?
Syndesmoses
sutures
gomphoses
What are syndesmoses joints?
e.g. distal end of radius and ulna
ligament connects bones
What are sutures?
only found in the skull
interlocking teeth-like projections
What are gomphoses?
found at the root of the teeth
periodontal membrane
What type of cartilaginous joints are there?
synchondrosis
symphyses
What are synchondroses?
e.g. between first rib and sternum
hyaline cartilage between articulating surfaces
What are symphyses?
e.g. pubic symphysis
fibrocartilage disk
What kinds of synovial joints are there?
uniaxial - hinge, pivot
biaxial - saddle, condyloid
multiaxial - ball and socket, gliding
Describe the uniaxial joints
hinge - e.g. elbow, flexion and extension
pivot e.g. between C1 and C2, rotation
Describe the biaxial joints
saddle - e.g thumb joint. flexion, extension, adduction and abduction
condyloid - between radius and carpal bones - flexion, extension, adduction and abduction
Describe the multi axial joints
ball and socket - e.g. shoulder - wide range
gliding - e.g between articulating facets of vertebrae. Gliding
what are the three types of cartilage?
hyaline cartilage
elastic cartilage
fibrocartilage
How do chondrocytes get their nutrients?
only through diffusion from the periosteum or synovial fluid - cartilage is avascular unlike bone
Describe hyaline cartilage
most common
both collagen and elastic fibres
articular surfaces of bones, tracheal rings, bronchi of lungs, tip of the nose
Describe elastic cartilage
large numbers of elastic fibres
gives form to external ear, epiglottis, eustachian tubes
Describe fibrocartialge
small quantities of matrix and abundant fibrous elements
strong, rigid
pubis symphyses, IV disks, near site of attachment of some large tendons to bones
what are the main changes seen in an osteoarthritic joint?
thickened capsule cyst formation and sclerosis of subchondral bone fibrillated cartilage osteophytic lipping synovial hypertrophy altered contour of bone
What causes damage to cartilage in OA?
decreases in water content, proteoglycan synthesis, collagen cross linking, size of GAGs and hyaluronic acid
traumatic damage
What is osteoarthritis?
progressive disorder of the joints caused by gradual loss of cartilage and resulting in the development of bony spurs and cysts and the margin of the joint
What are the causes of OA?
primary - degenerative
secondary - trauma, hip dysplasia, infection, diabetes
who is most affected by OA?
women over 45
What is seen in an X-ray of an OA joint?
joint space narrowing
osteophytes
subchondral bone sclerosis
cyst formation
What is ECM?
extracellular matrix
a complex network of proteins and polysaccharides
secreted locally
provides structural, adhesive and biochemical signalling support
What makes up ECM?
fibres - collagen and elastin
ground substance - proteoglycans, glycosaminoglycans, glycoproteins
What are the functions of ECM?
mechanical and structural support
tensile strength
determines cellular movment
what are the five classes of macromolecules found in ECM?
collagens elastin proteoglycans glycosaminoglycans other glycoproteins
where is type I collagen found?
dermis, tendons, ligaments, bones
where is type II collagen found?
hyaline cartilage
Where is type III collagen found?
liver, bone marrow, lymphoid organs
Where is type IV collagen found?
basement membrane
Where is type V collagen found?
linker to basement membrane
Describe GAGs
also called mucopolysaccharides
chains of repeating disaccharide units
carbohydrate component of proteoglycans
What GAG is found in the synovial fluid?
hyaluronic acid
What GAGs are found in cartilage?
chondroitin sulphate and keratan sulphate
What GAG is found in the basement membrane?
Heparin sulphate
what makes aggrecan and where is it found?
chondroitin sulphate and keratan sulphate
cartilage
What is perlecan made from and where is it found?
heparan sulphate
basement membrane
What is syndecan made from and where is it found?
chondroitin sulphate and keratan sulphate
cartialge
What is decorin made from and where is it found?
chondroitin sulphate and dermatan sulphate
wide spread
Give examples of 5 glycoproteins
fibrillar fibronectin laminin entactin tenascin
What does fibrillin do?
controls deposition and orientation of elastins
what does fibronectin do?
linker role in BM
What does laminin do?
primary organiser in BM
What does entactin do?
linker role in BM
What does tenascin do?
linker role in connective tissue
How is collagen made?
synthesised as pro collagen
post-translational modification - glycosylation and hydroxylation
assembled as triple helix
How is elastin made?
synthesised as tropo elastin
post-translational modification - hydroxylation
assembled in fibrillin scaffold, cross-linked fibres
What are the three layers of the basement membrane?
lamina lucida
lamina densa
lamina fibroreticularis
what is the basement membrane composed of?
collagen
laminin
perlecan
entactan
what are the functions of the basement membrane?
support binding to underlying connective tissues mediates signalling determines cell polarity permits flow of nutrients path for cell migration barrier to downward growth
Give examples of disorders of BM
cancer - epithelial tumours malignant when breach BM
Diabetes - thickening of BM of glomerulus alters function
epidermolysis bullosa - attachment of epidermis to BM
Good pastures syndrome - autoantibodies to collagen IV destroy BM in lung and glomerulus
A condition caused by problem in elastin
supravalvular aortic stenosis
A condition causes by a problem with fibrillin I
Marstan syndrome
A condition caused by a problem with collagen
etlers danlos syndrome
a condition caused by problem in keratan sulphate
macular corneal dystrophy
a condition caused by problem with perlecan
Silverman-Handermaker type of dyssegmental dysplasia (DDSH) lethal dwarfism
