Circulatory Shock, types and stages, compensatory mechanisms
Anatomy and histology of bone
1. ANATOMY AND HISTOLOGY OF BONE
PROFESSOR & HOD,
DEPTT OF ORTHOPAEDICS,
SILCHAR MEDICAL COLLEGE AND HOSPITAL
2. FUNCTION OF BONE
Serves as attachment sites for muscles.
Protection of organs(eg cranium,ribs
and pelvis).
Acts as reservoir for mineral in the body
99% calcium stored as hydroxyapatite
crystals.
3. BONE FORMS
LONG BONES
Formed by
enchondral
ossification.
Primary in shaft and
and sec. growth
centers
FLAT BONES
Formed by
intramembranous
ossification.
eg pelvis,scapula.
4. PARTS OF LONG BONESs
DIAPHYSIS-Shaft,made of thick cortical
bone,filled with bone marrow.
METAPHYSIS –Widening of bone near
the end made of cancellous bone.
EPIPHYSIS –End (usuallyarticular) of
bone,forms from secondary ossification
centers.
5.
6.
7. MICROSCOPIC BONE TYPES
WOVEN- Immature or pathologic bone,
poorly organised not stress oriented.
eg bones in infants ,fracture callus and
pathological tumours.
8. LAMELLAR TYPES
Mature bone highly organised with stress
orientation.
Mature cortical and cancellous bone are
made of lamellar bones.
9.
10. STRUCTURES OF CORTICAL
BONES
Strong dense bone,constitute 80% of skeleton.
Composed of multiple osteons.
Osteons are made up of concentric bone
lamellae with a central canal(haversian canal)
containing osteoblasts.
11.
12.
13. Lamellae are connected by canaliculi,
cement lines mark outer limit of osteon,
cortical bone is found in diaphysis of long
bones.
Volkmann′s canals – radially oriented ,
have arteriole and connect adjacent
osteons.
14. STRUCTURE OF CANCELLOUS
BONE Crossed lattice structure,makes upto
20% of the skeleton.
High bone turnover rate,bone is resorbed by
osteoclasts in howship lacunae and formed on the
opposite side of trabeculae.
Osteoporosis is common and found in vertebral
bodies,femoral neck,distal radius , tibial plateau and
found in metaphysis and epiphysis.
19. INORGANIC PHASE
Approx 60% of body weight.
Ca10(po4)6(OH)2 is primary mineral in bone.
Adds compressive strength .
Brushite is secondary mineral in bone.
20. ORGANIC PHASE
Collagen
Known as osteoid before its mineralization
Approx 35% of bone weight.
Type 1 collagen gives tensile strength.
Proteoglycans – Hyaluronic backbone with
multiple glycosaminoglycans.
gives compressive strength.
21. Non collagenous protein- Osteocalcin
is indicator of bone turnover rate.
eg Pagets disease.
osteonectin and osteopontin.
Cells include osteoblasts,osteocytes and
osteoclasts.
22. OSTEOBLASTS
Produce bone matrix ,makes type 1
collagen.
Follow osteoclasts in cutting cones.
Receptors –PTH ,vitamin D,glucosteroids
estrogens,PGs.
23. OSTEOCYTES AND OSTEOCLASTS
Osteoblast surrounded by bone matrix cons
90% of bone cells.
Preserves bone,long cell process
communicate via canaliculi receptors include
PTH and calcitonin.
Osteoclast are large multinucleated derived
from monocytes and macrophages absorbs
bone and found in howship lacunae.