chapter 6 - skeletal system
6.1 BONE FUNCTION
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ab- from
acetabulum- vinegar cup
ad- toward
amphi- both sides
arthros - joint
blast- precursor
circum - around
clast- break
clavius- clavicle
concha- shell
corona- crown
cranio- skull
cribrum- sieve
dens- tooth
dia- through
duco- to lead
e- out
gennan- to produce
vocab
gomphosis- a bolting together
in- into
infra- beneath
lacrimea- tears
lamella- thin plates
maleolus- little hammer
meniscus- crescent
osteon- bone
penia- lacking
planta- sole
porosus- porous
septum- wall
stylos- pillar
supra- above
sutura- screwing together
teres- cylindricals
trabecula- wall
trochlea- pulley
vertere- to turn
support
1.the bones in legs and pelvis support the trunk
2.the atlas (first vertebra) supports the skull, etc.
protection
of underlying organs
body movement
1.skeletal muscles attached to bones by tendons. - serves as levers to move bones
hematopoiesis
definition: blood cell formation 1. all blood cells are formed in the red marrow of certain bones
inorganic salt storage
1.bones store many minerals EX: calcium, phosphorus, etc. 2.also a means of calcium homeostasis 3. bone remodeling and repair
energy storage
- yellow marrow in the shaft of long bone 2. serve as an important chemical energy reserve
6.2 BONE STRUCTURE
bones are classified according to their shape
Long bones- consist of a shaft with two ends EX: thigh bone = femur, Upper arm bone = humerus
short bones- are cube like EX: wrist bones = carpals, ankle bones = tarsals
flat bones- thin and usually curved EX: most skull bones, breast bone = sternum, shoulder blades = scapulae, rubs
irreg. bones- not long, short, or flat EX: vertebrae, auditory ossicles
sesamoid bones- develop within a tendon 1.the patella is a human sesamoid bone
parts of a LONG BONE
diaphysis = shaft 1.consists of a central medullary cavity (filled with yellow marrow) 2. surrounded by a thick collar of compact bone
epiphyses = expanded ends 1. consist mainly of spongy bone 2. surrounded by a thin layer of compact bone
epiphyseal line = remnant of epiphyseal disk/plate 1.cartilage at the junction of the diaphysis and epiphyses (growth plate)
periosteum = outer, fibrous, protective covering of diaphysis 1. richly supplied with blood and lympth vessels, nerves (Nutrient Foramen: perforating canal allowing blood vessels to enter and leave bone) 2. osteogenic layer contains osteblasts and osteoclasts 3.serves as insertion for tendons and ligaments
endosteum = inner lining of medullary cavity. 1.contains layer of osteoblasts and osteoclasts
articular cartilage = pad of hyaline cartilage on the epiphyses where long bones articulate or join. "shock absorber"
parts of FLAT BONE
proximal epiphysis, diaphysis, distal epiphysis
articular cartilage, spongy bone, blood vessels, epiphyseal line, marrow cavity, endosteum, compact bone, periosteum
hematopoietic tissue (red marrow) is located in the spongy bone within the epiphyses of long bones and flat bones
Chemical composition of Bone
(organic components 35%) cells
osteoprogenitor cells
1, derived from mesenchyme 2.can undergo mitosis and become osteoblasts
ostroblasts
- form bone matrix by secreting collagen 2.cannot undergo mitosis
osteoclasts
- functions in bone resorption 2.import in development, growth, maintenance, and repair of bone
osteoid
1.primarily collagen 2.gives bone its high tensile strength 3.contains glycolipids and glycoproteins
(inorganic components 65%)
hydroxyapatite (mineral salts)
- primarily calcium phosphate 2.gives bone its hardness or rigidity
microscopic structure of compound bone
compact bone is solid dense and smooth
structural unit = haversain system or steon
microscopic structure of spongy (cancellous) bone
elongated cylinders cemented together to form the long axis of a bone
components of haversain system:
osteocytes (spider shaped bone cells that lie in the lacunae) that have laid down a matrix of collagen and calcium salts
in concentric lamellae (layers) around a central haversian canal
containing blood vessels and nerves
communicating canals within compact bone
canaliculi connect the lacunae of osteocytes
volkmann's canals connect the blood and nerve supply of adjacent haversian systems together
run at right angles and connects adjacent haversian canals
consists of poorly organized trabeculae (small needle like pieces of bone)
with a lot of open space between them
nourished by diffusion from nearby haversian canals
6.3 BONE DEVELOPMENT AND GROWTH
6.4 BONE REMODELING AND REPAIR
6.5 AGING PROCESS V. LIFE SPAN CHANGES
intramembranous ossification is when a bone forms on or within a fibrous CT membrane
flat bones are formed in this manner (skull bones, clavicles, etc)
endochondral ossification occurs when a bone is formed from hyaline cartilage model
a. most bones of the skeleton are formed in this manner
b. primary ossification center hardens as fetus and infant
c. secondary ossification centers develop in child and harden during adolescence and early adulthood
rate of remodeling varies
GROWTH AT THE EPIPHYSEAL PLATE
zone of resting cartilage
zone of proliferating cartilage
zone of hypertrophic cartilage
zone of calcified cartilage
distal femur is replaced every four months
diaphysis may not be fully replaced during one's lifetime
osteclasts are large multinucleated cells responsible for bone resorption
control of bone remodeling / calcium homeostasis
2 hormones: parathyroid hormone and calcitonin hormone
factors affecting bone development growth and repair
minerals needed for bone remodeling
calcium, phosphorus
vitamins needed for bone growth, remodeling, repair
vitamin D,C,A,B12
hormones needed for bone growth and remolding
human growth hormone, sex hormones: estrogens and androgens, thyroid hormones, PTH and calcitonin
exercise increases bone growth
height decreases begins at around age 33
by 70 bone loss between sexes is similar
fractures increase as bone ages
osteopenia osteoporosis
over age 45 :
29% of women
18% of men
after menopause
less common in men under 60