Bone tissue Flashcards
What is osteology?
the study of bones
what is osseous tissue
bone
the hardening process of bones is called
calcification/ mineralisation
list types of bones
flat bones
short bones
long bones
irregular bones
list flat bone examples
cranial bones sternum scapula ribs hip bones
list long bones
femur
humerus
tibia
fibula
list short bones
carpals
tarsals
list irregular bones
sphenoid,
ethmoid
general anatomy of long bone
-enclosed by outer compact (dense/lamellar) bone
-medullary cavity for bone marrow
-at the end of the bone the central space is occupied by loosely organised form of osseous tissue called spongy (cancellous) bone
diaphysis
epiphysis
epiphyseal line
- externally bone is covered in sheath called periosteum
which provides strong attachment for muscles and tendons - in kids - epiphyseal plate of hyaline cartilage separates the marrow spaces of the epiphysis and diaphysis
bone cells
-osteogenic (osteoprogenitor cells) are stem cells that develop fromn embryonic mesenchymal cells
found in the endosteum
they multiply and continually and go on to form into osteoblasts
-osteoblasts - are bone forming cells
-osteocytes - former osteoblasts, that have become trapped in the matrix they deposited
-osteoclasts - bone dissolving cells
what is the formation of bone called
ossification or osteogenesis
two methods of formation of bone
intramembranous and endochondral ossification
intramembranous - produces flat bones of the skull and most of the clavicle
endochondral - process whereby the bone is preceded by hyaline cartilage model
where is the thickest part of a long bone
the middle of the shaft - where most stress is applied
classification of fractures
stress fracture- caused by abnormal trauma to a bone, such as fractures incurred in falls, athletics and military combat
pathological fractures - break in bone weakened by some other disease, such as bone cancer, osteoporosis, usually caused by a stress that would not normally fracture a bone
- also classified by direction of fracture line, whether the skin is broken or not, whether the bone is cracked or broken into separate pieces
stages of bone healing post fracture
1- formation of hematoma and granulation tissue
a bone fracture severs blood vessels of the bone and periosteum, causing bleeding and the formation of a blood clot (fracture haematoma). blood capillaries soon grow into the clot, while WBCs invade the tissue from both the periosteal and medullary sides of the fracture. Osteogenic cells become very abundant within the 48 hrs of injury. All of the capillary and cellular invasion converts the blood clot to a soft fibrous mass called granulation tissue
2- formation of a soft callus - fibroblasts deposit collagen in the granulation tissue, while some osteogenic cells become chondroblasts and produce and produce patches of fibrocartilage called the soft callus
3- conversion to hard callus- other osteogenic cells differentiate into osteoblasts which produce a bony collar called the hard callus - it takes 4-6 weeks for the hard callus to form - important that a broken bone be immobilised by traction or a cast to prevent re injury
4- remodelling - hard callus persists for 3-4 months
meanwhile osteoclasts dissolve small fragments of broken bone and osteoblasts deposit spongy bone to bridge the gap between the broken ends. gradually fills to become compact bone in manner similar to intramembranous ossification.
