Skeletal System 7.2

Classifications of bones

long, short, flat, or irregular

long bones

• longitudinal axes and expanded ends

• ex: forearm and thigh bones

short bones

• roughly equal lengths and widths

• wrist and ankle bones

• special type called sesamoid or round bone

• typically small and nodular and develops within a tendon or adjacent to a joint

irregular bones

• variety of shapes

  • most connected to several other bones

• ex: vertebrae and many facial bones

flat bones

• platelike structures with broad surfaces

• ex: ribs, scapulae, sutural bones

epiphysis

the expanded portion at the end of the long bone

farthest from trunk of body called distal epiphysis

articular cartilage

outer surface of the articulating portion of the epiphysis coated with a layer of hyaline cartilage

diaphysis

shaft of the bone, between the epiphysese

epiphyseal line

region where epiphysis and diaphysis fuse together during growth

while bone still growing, called epiphyseal plate, or growth plate

periosteum

tough covering of dense connective tissue (CT) that completely encloses the bone, except for the articular cartilage on the bone’s ends

compact bone

makes up the wall of the diaphysis

aka cortical bone

continuous EM with no gaps

spongy bone

makes up epiphyses

aka cancellous bone

thin layers of compact bone on their surfaces

trabeculae

makes up spongy bone

numerous branching bony plates

helps reduce bone’s weight

medullary cavity

the hollow chamber that is continuous with the spaces of the spongy bone in the diaphysis of a long bone

endosteum

thin layer of cells that lines the medullary cavity

marrow

specialized type of soft CT that fills the medullary cavity

lacunae

bony chambers that osteocytes occupy

lamellae

forms concentric circles around central canals and hosts lacunae

canaliculi

how osteocytes exchange substances with nearby cells

living tissues that make up a bone

dense CT, blood, cartilage, nervous tissue, bone tissue

functions of bone tissue

supports, protects, produces blood cells, and stores minerals

the _______ is a tough CT that covers the outer portion of the bone, including the diaphysis

periosteum

the periosteum is located ____ and plays a role in ____.

in the medullary cavity; mineral balance

most bones have both types of bone tissue. the more superficial one is ___ bone which overlies ___ bone

compact/cortical; spongy/cancellous

the ___ is the vascular CT membrane that covers bones and plays an important role in bone growth and repair

periosteum

in ___, bone mass declines, bones easily fracture and may spontaenously break because they no longer can support body weight

osteopenia

the body of a mature bone cell (osteocyte) occupies a small chamber called

lacunae

the boney matrix of compact bone is organized into concentric circles called ___ that encircle central canals

lamallae

osteoporosis is characterized by ___

fragile bones that fracture easily

the two prominent components of bone’s EM are the protein ___ and inorganic ___.

collagen, salts

blood vessels run through a tunnel that is situated in the middle of an osteon. this tunnel is called a ___ ____.

central canal

what are canaliculi?

spaces in bone that house the cellular processes of osteocytes

the lamellae in compact bone are arranged in cylinder-shaped units called __.

osteons

the EM of bone tissue is largely composed of what two components?

collagen and inorganic salts

osteons are the structural unit of ___ bone, and contain ___ in the center.

compact; blood vessels and nerves

bone is hard due to ___ ____ but resilient due to ___

inorganic salts; collagen

perforating canals connect __ and communicate with the bone surface

central canals

in a bone, where can bone marrow be found?

irregular spaces in spongy bone, medullary cavity, central canals of compact bone

where is marrow found in bone?

in the spaces of spongy bone