Lecture 7 Flashcards
(29 cards)
information about bones
-206 bones
- consists if organic an inorganic elements
- bone forming cells are osteoblasts and osteocytes
- bone digesting cells are osteoclasts
- during bone development osteoblast predominates but when the skeleton reaches maturity, action of osteoblasts and osteoclasts are equal and by the 3rd decade, osteoclast predominates
what is remodelling
constant breakdown and renewal of bones
2 different types of ossification
direct: intramembraneous ossification
pre- existing cartilage:endochondral ossification
what is achondroplasia & Thanatrophoric
- congenital
- dwarfism
- autosomal dominant
- defect in cartilage synthesis growth due to mutation of gene FGFR3 on chart arm of chromosome 4, causing failure of longitudinal bone growth and short limbs
FGFR3 is a receptor with tyrosine kinase that transmits intracellular signals, singles transmitted by FGFR3 inhibit the proliferation and function of. growth plate chondrocytes
thanatophoric is more thermal and we have extreme shortening of limbs and also an extremely small thorax which can be the cause of fatal respiratory failure.
achondroplasia occurs as a sporadic mutation, their membraneous ossification is not affected
osteogenesis imperfecta
brittle bone disease
autosomal dominant
diff types
many genes mutated that encode for collagen type 1 so it results in too little bone causing skeleton fragility
we have a defect in the alpha 1 or alpha 2 chains of type 1 collagen, most fractures happen in the diaphysis
hearing loss and blue sclera in both eyes and deformed teeth.
4 clinical features
- osteoporosis
- blue sclera
- dentinogensis imperfecta
- hearing impairment
osteopetrosis
congenital and rare
- dysfunction of osteoclasts, decrease in turn over rate
so we have tick and dense bones and also there is a carbonic anhydrase deficiency.
- higher tendency of recurrent infections
4 metabolic bone diseased
hyperparathyroidism
osteoporosis
parents bone disease
osteomalacia
osteomalacia and rickets
osteomalacia in adults and rickets in children
- abnormal calcification and mineralisation due to vitamin D deficiency
due to:
- malnutrition
- malabsorption
- renal diseases
pagets disease
excessive uncontrolled destruction of bone by abnormally large and active osteoclasts, there is a production of physically weak bones
can result from a paramyovirus
asymptomatic
ape like post, pain in back, joints, skeletal deformity, hearing is affected
hyperparathyroidism
excessive secretion of PTH produced increased osteoclastic activity, excessive restriction of cortical and tabular bone
osteoporosis
reduced bone mass leading to to bone fragility
slowly progressive increase in bine erosion
causes :
primary - due to ageing or postmenopausal state in women due to the drop of oestrogen levels, envirmoent, decreased physical activity, women at higher risk then men
secondary - endocrine disorders, e.g hyperthyroidism, acromegaly, obesity, corticosteroid therapy.
osteoporosis fractures: neck of femur, wrists
diagnosis
prognosis
prevention
of osteoporosis
diagnose: X ray, dual emission
prognosis: patients have increase mortality rate and hope fractures can lead to decreased mobility
- vertebral bodies fractures can lead to progressive loss of height and pain or may cause deformity of the spine
- prevention , goof diet and train g hormonal replacement therapy
stages of bone healing
healing by callus formation
- haematoma formation (occurs immediately
- inflammation and cellular proliferation ( 8 hour to 1-2 weeks, migration of inflammatory cells)
regulation of fracture healing
- TGF-B: promotes proliferation or diff stem cells and stimulates collagen synthesis
- PDGF: stimulates T1 collagen synthesis by osteoblast and stimulates osteoclast resorption
- FGF: stimulates fibroblast proliferation, stimulates angiogenesis
- VEGF: stimulates angiogenesis
types of bone healing
- direct bone healing (primary bone healing)
- indirect bone healing ( secondary)
avascular necrosis
osteonecrosis, aspic necrosis, ischemic boen necrosis
- cellular death of bone components due to interruption of blood supply
- affects bones w a single terminal blood supply
osteomyelitis
infection of the bone leading to inflammatory process
microorganisms can reach the bones via blood stream, or ny direct invasion
factors affecting development:
- virulence, host factors, local factors
2 types:
hematogenous - bavterial seeding from blood, mainly seen in children, metaphysics at the end of long lines in children and vertebrae in adults
direct - open fracture or surgical operation, involves multiple organisms mainly S aureus
bone tumors
primary
secondary (metastasis) ]
bone forming tumors - osteoma, osteoid osteoma, osteosarcoma
miscellaneous tumor - Ewing tumor, giant cell
cartilage forming tumor - chondroma, osteochondroma, chondrosarcoma
osteoma
osteoma are benign lesions of bone that in
many cases represent developmental
aberrations or reactive growths rather than true neoplasms.
Osteosarcoma
Osteosarcoma is a
bone-producing malignant
mesenchymal tumor .
*Osteochondromas
*Osteochondromas are mushroom shaped and range in size from
1 to 20 cm.
*The outer layer of the head of the osteochondroma is composed
of benign hyaline cartilage varying in thickness
Newly formed bone forms the inner portion of the head and stalk,
with the stalk cortex merging with the cortex of the host bone.Osteochondromas
chondrosarcoma
■Chondrosarcomas comprise a
variety of tumors sharing the
ability to produce neoplastic
cartilage
giant cell tumor
This is a neoplasm that contains
large numbers of osteoclast like
giant cells admixed with
mononuclear cells.
■ These tumors are slightly more
common in females.
metastatic
Metastatic tumors are the most
common malignant tumor of
bone.
