skeleton Flashcards
what is skeletal system
consists of bones, cartilage, ligaments tightly joined to form a strong, flexible framework for the body
osteology
skeleton
bone is living tissue
adult human = 206 bones
newborn = 350 bones, eventually fuse together
functions of skeletal system I
support = structural support and framework for attachment of soft tissues and organs
movement = attachment of skeletal muscles to bones either side of joints enables movement
protection = many soft tissue and organs surrounded by. bone
functions of skeletal system II
storage of minerals = calcium salts, important for maintaining normal conc of calcium and phosphate ions
storage of lipids in areas of yellow marrow
blood cell production
bone formation and growth
ossification = formation of bone and replacing other tissues with bone
two forms;
endochondral = bone replaces existing cartilage model
intramembranous = bone develops directly from mesenchyme or fibrous connective tissue
endochondral ossification
bone originates as cartilage model
cartilage = flexible connective tissue found in many areas of Body
chondrocytes only cells found in healthy cartilage
produced and maintain cartilaginous matrix, which consists mainly of collagen
stages of endochondral ossification
stage 1 = chondrocytes begin to increase in size while matrix calcifies around them
chondrocytes become starved and die
stage 2
- blood vessels grow into perichondrium
- cells in perichondrium differentiate into osteoblasts and begin forming bone around edge of cartilage shaft = periosteum
stage 3:
- blood vessels and fibroblasts migrate into the cartilage. fibroblast differentiate into osteoblasts
- calcified cartilage matrix breaks down and is replaced by trabecular bone
stage 4:
- wave of ossification spread towards end of long bone
- osteoclast absorb bone from centre leaving marrow cavity
- bone grows inwards from periosteum forming compact bone surrounding the marrow cavity
stage 5:
- capillaries and osteoblast migrate into epiphyses and ossification begins = known as secondary ossification centres
- timing of appearance of secondary ossification centres vary greatly
immature long bone
formation of trabecular bone in epiphysis leaves two areas of cartilage
an articular cartilage = articular cartilage from another bone, prevent bone on bone articulations
growth of cartilage
interstitial growth
- growth from within
appositional growth = new layers of cartilage are added to the surface
factors that affect bone development I
normal bone growth and maintenance depends on combination of environmental, nutritional and hormonal factors
genetic
activity = bone adapts to meet functional demand
nutritional = availability of nutrients
hormonal = several hormones, calcitonin, parathyroid hormone, growth hormone
pathological = disease processes, infection, bone tumours, tuberculosis can affect bone growth
aging
divisions of skeleton
divided into:
- axial
- appendicular
axial division
forms central supporting axis of body
includes: skull, vertebral column, ribs, sternum
apendicular division
includes: bones of upper limb, pectoral girdle, bones of lower limb and pelvic girdle
classification of bone by shape
long bones = elongated tubular shafts, central medullary cavity, expanded ends for articulation
short bones = thin outer shell of compact bone with interior completely occupied by cancellous bone
flat bones = typified by bones of vault of the skull, where structure consists of two shells of compact bone, separated by layer of cancellous bone
irregular bones = anything that won’t fit into other categories
sesamoid bone = formed In tendon
the vertebral column
32-33 bones
divided into 5 regions
vertebral column = not straight and rigid, but instead consists of 4 curves
- cervical curvature
- thoracic curvature
- lumbar curvature
- sacral curve
produce S shaped spine, compared with C shaped spine present at. birth. allow for bipedal walking by ensuring head is balanced over bodies centre of gravity
