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30 terms

Osseous tissue and bone structure

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Five primary function of skeletal system
Support, storage of minerals & lipids, blood cell production, protection, leverage
Six bone shapes
Sutural, irregular, short, flat, long, sesamoid
Long bone
Fairly long & slendar, located in the arm, forearm, thigh, leg, palms, soles,fingers & toes, fermur is the largest and heaviset bone
Sesamoid bone
Small,flat & shaped somehat like a seame seed, located near joints at the knee, hands and feet
Sutural bone
Small flat, irregularly shaped bones between the flat bones of the skull
Irregular bone
Complex shapes with short, flat, notched or ridged surfaces. Spinal vertebrae, pelvis, some skull bones.
Short bone
Are small and boxy. Found in carpal and tarsal bones
Flat bone
Are thin, parallel surfaces, parietal bones of the skull, protection for underlying soft tissue. Found in sternum, rib, and scapulae.
Epiphysis
Wide part of each end, articulation with the bones, mostly spongy (cancellous) bone, covered witht the compact bone (cortex).
Diaphysis
The shaft, a heavy wall of compact bone or dense, a central space called medullary cavity
Metaphysis
Where diaphysis and epiphysis meet
Diploe
Within cranium, the layer of spongy bone between the layers of compact bone
Four type of cells
Osteocytes, osteoblasts, osteoclasts, osteoprogenitor cells
Osteocyte
Mature bone cells, live in lacunae, between layer (lamellae) of matrix, does not divide,
Function: Maintain proteins & minerals content of matrix, help repair damaged bone
Osteoblast
Immature bone cells that screte matrix compound (osteogenesis), osteoid matrix produced but not yet calcified to form bone, surround by bone become osteocytes.
Osteoprogenitor cell
Assist in fracture repair, located in endosteum, the inner, cellular layer of periosteum Mesenchymal stem cell (partially differentiated squamous), divide to become osteoblasts
Osteoclast
Secrete acids, protein, and digesting enzymes, giant multinucleate cells, dissolve bone matrix and released stored minerals(osteolysis), are derived from cells that produce macrophages, found in small depression on the endosteal surfaces
Osteon
Osteocytes are arranged in concentric lamellae, around the central canal containing blood vessels.
Perforating canal
Perpendicular to the central canal, carry blood vessels into bone and marrow.
Spongy bone
Does not have osteons, open networks of trabeculae, red bone marrow is found between trabeculae of spongy & blood vessels, supplies nutrients to osteocytes, trabeculae has no blood vessels, yellow bone marrow stored fats.
Calcification
Process of depositing calcium salts, occurs during bone ossifications and other tissues
Endochondral
Ossifies bone that originate as hyline cartilage
Effects of Exercise on bone
Minerals recycling allow bone to adapt to stress, heavily stress bones becomes thicken & stronger, a lack of exercis can cause weak bone
Calcium homeostatis
Skeleton calcium reserve, bones store calcium & other minerals, calcium is the most adundant, calcium ion vital to membranes, neuron, muscle cells, especially the heart.
calcium regulation
Calcium ions in body fluid must be closely regulated, homeostasis is maintained by calcitonin & parathyroid hormone which control storage
Calcitonin & parathyroid hormone
Bones (where calcium is stored)
Digestive tract (absorbed calcium)
kidneys (excreted calcium)
Parathyroid hormone
Increases calcium ions levels by: stimulating osteoclasts, increasing intestinal absorption of calcium, decreasing calcium excretion of kidney
Calcitonin
Secreted by "C" cells (parafollicular cells) in thyroid, decreases calcium ions levels by: inhibiting osteoclast activity, increasing calcium excretion at kidney.
Calcium phosphate
About two-thirds of bone matrix is.
Collagen fiber
About one-third of bone matrix is protein.