bones Flashcards
What are the functions of bones?
support, protection, movement/leverage, storage, and blood cell formation
Where does hematopoiesis occur?
red bone marrow
What is bone?
a supporting connective tissue; mostly composed of calcium phosphate salts and collagen fibers
What is the diaphysis?
composed of compact bone and surrounds the marrow cavity
What is the periosteum?
membrane that covers and protects the diaphysis
What is the epiphyses?
composed of spongy bone surrounded by a thin layer of compact bone; found at the end of long bones and covered by articular cartilage
What is articular cartilage?
glassy, hyaline cartilage that covers the epiphyses to provide a smooth, slippery surface at the joints
What is the epiphyseal plate?
growth plate composed of hyaline cartilage in young bone that causes lengthwise growth of long bones and turns to bone after puberty
What are the functions of the periosteum?
isolates the bone from surrounding tissue, provides a route for blood vessels and nerves, & actively participates in bone growth and repair
What are Sharpey’s fibers?
perforating fibers; anchor tendons and ligaments to the periosteum of the bones & provides an extremely strong attachment
What is the endosteum?
layer that lines the medullary cavity
What are the functions of the endosteum?
active during bone growth, repair, and remodeling, covers the trabaculae of spongy bone and lines the inner surface of the central canals, & it is where osteoblasts can remove or deposit matrix
What is the medullary cavity?
central cavity/marrow cavity; it is where red and yellow bone marrow are stored
What is the trabeculae?
open network matrix with no capillaries
What is red marrow?
contains blood vessels; fills the spaces between the trabeculae
What is yellow marrow?
adipose (fat) tissue; an energy reserve
What are the functions of osteocytes?
secrete chemicals that dissolve the bony matrix causing minerals to be released into circulatory system & help repair damaged bone
What are osteoblasts?
produce (build) new bone matrix by a process called osteogenesis
What are osteoclasts?
remove and recycle (break down) bone matrix
What is the bone matrix?
non-living part of bone
What is the osteon (haversian) system?
osteocytes are arranged in concentric layers/circles (matrix) called lamellae (“little lakes”) around a central canal
What are osteocytes?
mature bone cells found in the lacunae
What are lacunae?
“little lakes”; cavities containing osteocytes
What are haversian (central) canals?
they run lengthwise through the center; carries blood vessels and nerves to all areas of the bone
What are canaliculi?
tiny canals that connect bone cells; transport nutrients
What are perforating (Volkmann’s) canals?
pathway from the outside of the bone to its interior canals (run at right angles)
What is interstitial lamellae?
remainders of broken down pieces of lamellae; not full concentric circles
What are characteristics of long bones?
long and slender, have a shaft with heads at both ends, & mostly composed of compact bone
What are characteristics of short bones?
generally cube-shaped & mostly spongy bone
What are characteristics of sesamoid bones?
they form with tendons, small and flat, & shaped like a sesame seed
What are characteristics of sutural bones?
small, flat, irregular shaped bones between the flat bones of the skull, their borders are like a jigsaw puzzle, & range in size from a grain of sand to a quarter
What are characteristics of flat bones?
thin, flattened, and usually curved, provide protection for underlying soft tissues, & provide surface area for the attachment of skeletal muscles
What are characteristics of irregular bones?
bones that do not fit into the other catergories
What are some examples of long bones?
all bones of the limbs except the wrist & ankle bones
What are some examples of short bones?
bones of the wrist and ankle
What are some examples of sesamoid bones?
patella
What are some examples of flat bones?
ribs, scapula, sternum, & some skull bones
What are some examples of irregular bones?
vertebrae, hip bones, mandible, maxilla, & some skull bones
When does the bony skeleton begin to form?
6 weeks after fertilization and is composed of hyaline cartilage
What is endochondral ossification?
gradually converts the cartilage to bone during development (lengthening of bone)
What is appositional growth?
increases bone diameter at the outer surface
What are some characteristics of appositional growth?
occurs continuously through life, this process forms the circular lamellae, bone matrix is being added to the outer surface by osteoblasts while osteoclasts are removing bone matrix from the inner surface
What is bone remodeling?
the process where the bone matrix is continually recycled and renewed
What are characteristics of bone remodeling?
normal bone maintenance, controlled by calcium levels in blood and stress placed on bones, goes on throughout life, osteocytes continually remove and replace the calcium salts, & osteoblasts continually create new osteons
What are the effects of exercise on the bone?
heavily stressed bones become thicker and stronger & the stresses applied to bones during physical activity are essential to maintaining bone strength and bone mass
What are the hormonal & nutritional effects on bone?
bones need calcium, phosphates, magnesium, fluoride, iron, and manganese for normal growth and repair
What is calcitrol?
a hormone made in the kidneys needed for normal calcium and phosphate ion absorption in the digestive tract
What is Vitamin D3 used for ?
needed to make calcitrol
What do Vitamins A & C do?
stimulate osteoblast activity
What is scurvy?
loss of bone mass and strength due to Vitamin C deficiency
What is the function of Vitamins K & B12?
synthesis of proteins in normal bone
What stimulates bone growth?
the growth hormone (pituitary gland) and thyroxine (thyroid)
What is the function of sex hormones?
at puberty they stimulate osteoblasts to produce bone at a faster rate, narrowing the epiphyseal cartilage
What controls the balance of calcium and phosphate levels in bodily fluids?
calcitonin (thyroid) and parathyroid hormone (parathyroid)
What are some characteristics of calcium?
most abundant mineral in the body, accounts for 2-4 pounds of body weight, calcium ions are important in nerve and muscle cells especially the heart
What will a 30% increase in calcium result in?
coma; nerve and muscle cells become unresponsive
What will a 35% decrease in calcium result in?
nerves get so excitable that convulsions can occur
What will a 50% decrease in calcium result in?
death
What is the daily fluctuation of calcium ion concentration?
no more than 10%
What do the parathyroid hormone and calcitonin do?
coordinate the storage, absorption, and excretion of calcium ions
What occurs when calcium ions in blood are too low?
parathyroid hormone (PTH) is released by the parathyroid glands
What are the effects of the release of PTH?
stimulates osteoclast activity, increases absorption of calcium ions by intestines, & decreases excretion of calcium ions by the kidneys
What happens when calcium ions in blood are too high?
the thyroid gland releases calcitonin that inhibits osteoclast activity & increases excretion of calcium ions by the kidneys
What is the UL (upper/lower) ratio at birth?
1.7 : 1
What is the UL ratio by age 10?
1 : 1
What happens during puberty?
the female pelvis broadens & entire male skeleton becomes more robust
What starts happening between ages 30 and 40?
bones become thinner & weaker and osteoblast activity declines but osteoclast activity stays the same
What percentage of skeletal mass do men and women lose each decade?
men: 3% women: 8%
What areas lose the most mass?
epiphyses, vertebrae, and the jaws; results in fragile limbs, reduction in height, & loss of teeth
What is osteoporosis?
a bone-thinning disease affecting half of women over age 65
What areas are most susceptible to osteoporosis?
spine and neck of femur; caused by decline in estrogen, diet poor in calcium & protein, lack of Vit D, smoking, and lack of exercise
What is a fracture?
any crack or break in a bone caused by extreme loads, sudden impacts, or stresses from unusual directions
What is a reduction?
to realign or “fix” the fracture
What is open reduction?
surgical alignment
What is closed reduction?
manipulation of bone to realign
How are fractures named?
according to external appearance, location, and the nature of the crack or break
What is a closed (simple) fracture?
no break in the skin
What is an open (compound) fracture?
bone breaks through skin; possible infection and uncontrolled bleeding
What is a displaced fracture?
bones out of alignment
What is a nondisplaced fracture?
straight or normal alignment
What is a compression (impacted) fracture?
occur in vertebrae
What is a stress fracture?
bone becomes weak due to overuse; common in lower leg or foot
What is a spiral fracture?
produced by twisting force
What is an avulsion fracture?
occurs with extreme load from a tendon or ligament that forces a piece of bone to break off
What is a committed fracture?
shattered
What is a transverse fracture?
break at right angles to the long axis
What is a colles fracture?
occurs at distal end of radius; caused by reaching out to break a fall/extension of wrist
What is a greenstick fracture?
one side of the bone is fractured and the other side is bent; incomplete fracture that usually occurs in children whose bones haven’t completely ossified
What is an epiphyseal fracture?
occur where the matrix is undergoing calcification; if it occurs between the epiphysis and the epiphyseal cartilage; it can permanently stop growth
What is a depressed fracture?
break in a cranial bone (“crushed” portion of skull) with depression of bone in toward brain
What is a boxer’s fracture?
transverse fracture across the metacarpal neck; caused by striking an object with a closed fist; most common to pinky finger
What are the steps to repair fractures?
- hematoma formation
- fibrocartilaginous callus formation
- bony callus formation
- bone remodeling
What is a hematoma formation?
a large blood clot or hematoma develops to splint the area where bleeding occurs due to damaged blood vessels
What is fibrocartilaginous callus formation?
fibroblasts produce collagen fibers bridging the broken ends of the bone
What is bony callus formation?
external callus of bone forms around the fracture; osteoblasts start bridging the broken pieces together
What is bone remodeling?
the area is reshaped, external stresses must be applied; can take 4-12 months to be completed
What are the 2 types of bone markings?
projections/processes & depressions/cavities
What are projections/processes?
grow out from bone surface; sites for muscle, tendon, and ligament attachment & some form joints
What are depressions/cavities?
indentions in the bone; passageways for blood vessels, nerves, etc.
What is a process?
any bone prominence
What is a tuberosity?
large & rounded
What is a tubercle?
small & rounded
What is a trochanter?
very large, irregular process only found on femur
What is a crest?
narrow, prominent ridge of bone
What is an epicondyle?
raised area on or above a condyle
What is a spine?
sharp, slender, often pointed projection
What is a head?
bony expansion carried on a narrow neck
What is a facet?
smooth, nearly flat articular surface
What is a condyle?
rounded articular projection
What is a ramus?
arm-like bar of bone
What is a canal?
tube-like channel; connects different regions of the body
What is a meatus?
canal-like passageway
What is a sinus?
air-filled cavity within a bone
What is a fossa?
shallow depression; articular surface
What is a groove (sulcus)?
furrow
What is a fissure?
narrow, slit-like opening
What is a foramen?
round/oval opening through a bone
What is a notch?
indention on the edge of a bone