Osteoporosis
diseases in which bone resorption exceeds deposit. Matrix remains normal, but bone mass declines. Spongy bone of spine and neck of femur most susceptible(Vertebral and hip fractures common)
Paget's disease
Excessive and haphazard bone deposit and resorption cause bone to be made fast and poorly
osteomalacia
Bones are poorly mineralized, results in soft, weak bones (Pain upon bearing weight) Rickets on children
four stages of healing in a fracture
Hematoma formation, Fibrocartilaginous callus formation, bony callus formation, bone remodeling
Position of bone ends after fracture
Nondisplaced: ends retain the normal position Displaced: ends are out of normal alignment
Completeness of break
Complete: broken all the way through Incomplete: not broken all the way through
Whether skin is penetrated
Open (compound): skin is penetrated Closed (simple): skin is not penetrated
epiphyseal line
remnant of the epiphyseal plate, seen in adult bones
epiphyseal plate
Growth plate, made of cartilage, gradually ossifies
Long Bone
a bone that has a shaft and 2 ends and is longer than it is wide
Flat Bone
skull and the thoracic cage
Irregular Bone
spinal column (sacrum, vertebrae) and the pelvis
Sesamoid Bone
patella
Short Bone
tarsals (ankle bones), patella (kneecap), and carpals (wrist bones)
Look at a long bone and identify the parts
Closed Reduction
physician manipulates to correct position
Open reduction
surgical pins or wires secure ends
Hyaline cartilage
Provides support, flexibility, and resilience Most abundant type; contains collagen fibers only EX: Articular (joints), costal (ribs), respiratory (larynx), nasal cartilage (nose tip)
Elastic cartilage
Similar to hyaline cartilage, but contains elastic fibers EX: External ear and epiglottis
Fibrocartilage
Thick collagen fibers: has great tensile strength EX: Menisci of knee; vertebral discs
Red Marrow
found within trabecular cavities of spongy bone and diploë of flat bones, such as the sternum
Yellow bone marrow
made mostly of fat and contains stem cells that can become cartilage, fat, or bone cells Found in long bones
Yellow marrow can convert to red if...
person becomes anemic
Osteoblasts
Bone-forming cells that secrete unmineralized bone matrix called osteoid
Osteogenic cells
Mitotically active stem cells in periosteum and endosteum
Osteocytes
Maintain bone matrix
Bone lining cells
Flat cells on bone surfaces believed to also help maintain matrix (along with osteocytes)
Osteoclasts
bone resorption (breakdown of bone)
Endochondrial ossification
Bone forms by replacing Hyaline Cartilage. Forms essentially all bones inferior to base of skull, except clavicles
intramembranous ossification
Bone develops from Fibrous membrane Bones are called membrane bones Forms frontal, parietal, occipital, temporal, and clavicle bone
interamembranous ossification steps
-Ossification centers appear in the fibrous connective tissue membrane. -Osteoid is secreted within the fibrous membrane and calcifies. -Woven bone and periosteum form. -Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears.
endochondrial ossification steps
-Bone collar forms around hyaline cartilage model. -Cartilage in the center of the diaphysis calcifies and then develops cavities. -The periosteal bud invades the internal cavities and spongy bone forms. -The diaphysis elongates and a medullary cavity forms. Secondary ossification centers appear in the epiphyses. -The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages.
Growth hormone
most important hormone in stimulating epiphyseal plate activity in infancy and childhood
Thyroid hormone
modulates activity of growth hormone, ensuring proper proportions
testosterone
(males) at puberty promote adolescent growth spurts
estrogen
(females) at puberty promote adolescent growth spurts
What is diploe?
the spongy layer between the inner and outer compact layers of the flat bones of the skull.
Functions of bones
support protection movement triglyceride(fat) storage mineral storage blood cell formation hormone production
What is an osteon?
(Haversian system) structural unit of compact bone;Acts as tiny weight-bearing pillars
Sharpey's fibres
(bone fibres, or perforating fibres) are a matrix of connective tissue consisting of bundles of strong collagenous fibres connecting periosteum to bone
Fibrous layer
outer layer consisting of dense irregular connective tissue consisting of Sharpey's that secure to bone matrix
Periosteum
Fibrous layer, Osteogenic layer
Perforating (Volkmann's) canals
canals lined with endosteum that occur at right angles to the central canal
Central (Haversian) canal
runs through core of osteon, contains blood vessels and nerve fibers
appositional growth
growth in width
Interstitial growth
growth in length
What is responsible for the strength and allows bone to resist compression?
collagen fibres
What is the effect on calcitonin in humans?
lower calcium levels in your blood
What makes up spongy bone?
Spongy bone consists of plates (trabeculae) and bars of bone adjacent to small, irregular cavities that contain red bone marrow.
What is osteogenesis?
the process of bone tissue formation
Comminuted fracture
bone breaks into 3 or more fragments
Spiral fracture
a fracture in which the bone has been twisted apart
greenstick fracture
(incomplete fracture) bending and incomplete break of a bone; most often seen in children
Compound fracture
bone breaks through the skin
Displaced fracture
bone ends are out of normal alignment
Depressed fracture
broken bone portion is pressed inward
Simple fracture
bone is broken cleanly; the ends do not penetrate the skin
Compression fracture
bone is crushed
What is Wolf's law?
states that your bones will adapt based on the stress or demands placed on them. When you work your muscles, they put stress on your bones. In response, your bone tissue remodels and becomes stronger