Skeletal System
Monday, October 12, 2015
• Get out your leg bone diagrams
• Get out paper
• Get out something to write
with
Get out your skeletal system diagrams
• Using p. 144 as a guide, color code the axial
and appendicular skeleton
• Do anterior & posterior
• Use same color front & back
• Create a key / legend to go with your color
codes
Tomorrow
• Have hand & foot diagrams labeled
• Majority of class will be work day
• Wed. – Mrs. Glisson will not be here till 11 or
12; no office hours Wed. morning;
• Get out paper to take notes
Skeletal System Notes
Skeletal System Functions
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Muscle attachment
Protection & support
Blood cell production
Storage of minerals
Structure
• A bone’s shape make possible its function;
bony processes or grooves indicate places of
attachment for muscles
• Compact bones makes up the wall of the
diaphysis; the epiphyses are filled w/ spongy
bone
• Diaphysis also contains a hollow medullary
cavity that is lined w/ endosteum & filled w/
marrow
Microscopic structure
• Osteocytes are located within lacunae that lie in
concetric circles around osteonic canals
• Osteocytes pass nutrients & gasses in the matrix
through canaliculi
• Intercellular material consists of collagen &
inorganic salts
• Osteonic canals contain blood vessels & nerves
fibers, and extend longitudinally through bone
• In spongy bone, osteocytes & intercellular
material NOT arranged around osteonic canals
Bone Development & Growth
• Bones form by replacing connective tissue in
the fetus
• Some form within sheet-like layers of
connective tissue (intramembranous bones)
while others replace masses of cartilage
(endochondral bones)
Bone Development & Growth
• Intramembranous Bones = flat bones of the
skull; osteoblasts deposit bony tissue around
themselves
• Endochondral bones = most bones; first
develop as hyaline cartilage models & then are
replaced w/ bone
Homeostasis of Bone Tissue
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Osteoclasts tear down
Osteoblasts build bone
Happens throughout lifespan
An average of 3%-5% of bone calcium
exchanged annually
Specific Functions
• Support & Protection
– Give shape to head, thorax & limbs
– Provide support for body (i.e. pelvis & lower
limbs)
– Skull protects brain, ears, & eyes
• Body Movement
• Bones can act as levers
Specific Functions
• Blood cell formation
– 2 kinds of marrow occupy the medullary cavities
of bone
• Red marrow functions in the formation of red blood
cells, white blood cells, and platelets, and is found in
the spongy bone of the skull, ribs, sternum, clavicles,
vertebrae, and pelvis
• Yellow marrow occupies the cavities of most bones &
stores fat
Specific Functions
• Storage of Inorganic Salts
– The inorganic matrix of bone stores inorganic mineral salts
in the form of calcium phosphate; it is important in many
metabolic processes
– Calcium in bone is a reservoir for body calcium; when
blood levels are low, osteoclasts release calcium from bone
– Calcium is stored in bone under the influence of calcitonin
when blood levels of calcium are high
– Bone also stores magnesium, sodium, potassium &
carbonate ions
– Bones can also accumulate harmful elements such as lead,
radium and strontium
Organization
• Axial skeleton = skull, hyoid bone, vertebral
column (vertebrae & intervertebral disks), and
thorax (ribs & sternum)
• Appendicular skeleton = pectoral girdle (scapulae
& clavicles), upper limbs (humerus, radius, ulna,
carpals, metacarpals, & phalanges), pelvic girdle
(coxal bones articulating w/ the sacrum), and
lower limbs (femur, tibia, fibula, patella, tarsals,
metatarsals, phalanges).
For remainder of class…
•Work on skeletons