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 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 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