chapter 6: skeletal system

acromegaly

a condition caused by the overproduction of growth hormone in adults, characterized by a thickening of bones and an enlargement of cartilages and other soft tissues

appositional growth

the enlargement of a cartilage or bone by the addition of cartilage or bony matrix at its surface

bone tissue

a strong connective tissue containing specialized cells and a mineralized matrix of crystalline calcium phosphate and calcium carbonate

calcification

the deposition of calcium salts within a tissue

canaliculi

microscopic passageways between cells

-bone: permit the diffusion of nutrients and wastes to and from osteocytes

central canal

longitudinal canal in the center of an osteon that contains blood vessels and nerves

-aka Haversian canal

compact bones

dense bone that contains parallel osteons

diaphysis

the shaft of a long bone

endochondral ossification

the replacement of a cartilaginous model with bone

-formation of all bones except cranium, clavicles, and patella

endosteum

an incomplete cellular lining on the inner (medullary) surface of bones

epiphyseal cartilage

the cartilaginous region between the epiphysis and diaphysis of a growing bone

-epiphyseal plate

epiphysis

the head of a long bone

fracture

break or crack in the bone

-compound, transverse, spiral, greenstick, fissure, comminuted

intramembranous ossification

formation of bone within a connective tissue without prior development of a cartilaginous model

lamellae

concentric layers of bone within an osteon

medullary cavity

the space within a bone that contains the marrow

metaphysis

the region of a long bone between the epiphysis and diaphysis, corresponding to the location of the epiphyseal cartilage of the developing bone

ossification

replacement of a cartilagenous model with bone

-mode of formation for bones other than cranium, clavicles, sesamoid

osteoblast

cells that produce the fibers and matrix of bone

-osteoBlast = Build

osteoclast

cells that dissolve the fibers and matrix of bone

-osteoClast = consume

sutural bones

small irregular bones that form in fibrous tissue between the flat bones of the developing cranium

osteoctye

bone cell

-responsible for the maintenance and turnover of the mineral content of the surrounding bone

osteolysis

the breakdown of the mineral matrix of bone

osteon

the basic histological unit of compact bone

-consists of osteocytes organized around a central canal and separated by concentric lamellae

osteoporosis

reduction in bone mass that causes brittle, fragile bones and comprises normal function

parathyroid glands

four small glands embedded in the posterior surface of the thyroid gland that secrete parathyroid hormone

parathyroid hormone (PTH)

a hormone secreted by the parathyroid glands when blood calcium levels decrease below the normal range

-increased osteoclast activity, increased calcium uptake, decreased calcium ion loss by the kidneys

perforating canals

passageways within compact bone that extend perpendicular to the surface

periosteum

outer layer that surrounds a bone

-outer fibrous region and inner cellular region

sesamoid bone

bone that forms within a tendon

spongy bone

bone that consists of an open network of struts and plates that resemble a 3D garden lattice