Bones ch6 Flashcards
functions of skeletal system
support, storage of minerals, storage of lipids, blood cell production, protection, leverage
bones are classified by
shape, internal tissue organization, bone markings
long bones
long and thin; found in arms, legs, hands, feet, fingers, toes
flat bones
thin with parrallel surfaces; skull, sternum, ribs, scapulae
irregular bones
complex shapes, spinal vertebrae, pelvic bones
short bones
small and thick; ankle and wrist bones
sesamoid bone
not directly connected to other bones, develop inside tendons; patella
depressions or grooves
points of attachment
projections
where tendons and ligaments attach; articulation with other bones
tunnels
where blood and nerves enter bone
long bone structure (3 parts)
diaphysis, epiphysis, metaphysis
diaphysis
the shaft; heavy wall of compact bone, central space called medullary cavity (marrow)
epiphysis
wide part at ends, articulation with other bones, mostly spongy bone covered with compact bone
metaphysis
where diaphysis and epiphysis meet; hyaline cartilage until adulthood
flat bone structure
sandwich of spongy bone between two layers of compact bone
diploe
spongy bone in the cranium
membranes of bone
periosteum, endosteum
periosteum
outer fibrous layer with inner osteogenic layer: osteoblasts, osteoclasts, osteogenic cells (stem cells)
periosteum (nutrient and securement)
nerve fibers, blood vessels and lymphatic vessels via nutrient foramina; secured to bone by collagen and sharpey’s fibers
endosteum
delicate membrane on internal surface of bone, osteoblasts and osteoclasts; covers trabeculae and lines canals
red marrow cavities of adults
trabecular cavities of heads of femur and humerus and diploe of flat bones
red marrow cavities of children
medullary cavities and all spaces in spongy bones
osteocytes
Bone Maintainers: mature bone cells that maintain the bone matrix, live in lacunae, monitor and maintain mineral content and repair damage bone
osteoblasts
Bone Makers: immature bone cells that secrete matrix compounds (osteogenesis); if surrounded by bone they become osteocytes
osteoid
matrix produced by osteoblasts, but not yet calcified to form bone
osteoclasts
Bone Breakers: secret acids and protein digesting enzymes, giant multinucleate cells, dissolve bone matrix and release stored minerals (osteolysis); derived from stem cells that produce macrophages
Osteoprogenitor Cells
mesenchymal stem cells that divide to produce osteoblasts, located in the endosteum and inner cellular layer of periosteum; assist in fracture repair
homeostasis
bone making must balance with bone recycling
Anatomy of compact bone (osteon) 5
lamellae, central canal, perforating canal (volkmann), lacunae, canaliculi
Anatomy of spongy bone
open network of trabeculae, irregularly arranged lamellae, osteocytes and canaliculi; no osteon or central canal; red or yellow marrow
organic composition of bone
osteogenic, blasts, clasts, cytes, osteoid, proteoglycans, glycoproteins, collagen fibers
inorganic composition of bone
hydroxyapatites: mineral salts (65% of mass) mainly calcium phosphate,
mineral salts
responisble for hardness and resistance of compression
intramembranous ossification
from fibrous membranes (mesenchyme); flat bones; 1) mesench cluster 2) diff in to osteoprogen 3) divide to become osteoblasts
endochondral ossification
originate as hyaline cartilage; most bones except flat, 6 main steps:
interstitial vs apositional
increase the length vs. increase the thickness, remodeling of surfaces
epiphyseal plate cartilage 4 zones
proliferation (cartilage dividing), hypertrophic (increase size), calcification, ossification
hormones
growth hormones, thyroid hormones, testosterone and estrogen
wolfs law
greater stress= more bone deposition; support: handedness, curved bones, trabeculae, bony projections
bone remodeling
osteoclasts break down bone: lysosomal enzymes and acids; osteoblasts deposit; replaces minerals, recycles and renews matrix;
effects of excercise on bone
bones adapt to stress, stress makes thicker and stronger
bone nutrition
calcium, phosphate salts, small amt of magnesium, fluoride, iron and manganese; hormone calcitrol; vitamin d
calcium
most abundant mineral in the body, ions are vital to membranes, neurons, muscle cells (heart)
calcium homeostasis
calcitonin/thyroid (too much) and parathyroid hormone (too little), controls storage (bones) absorption (Dig) and excretion (kid)
osteomalacia and rickets
when calcium salts are not deposited, caused by vit d or calcium deficiency
osteopenia
general bone loss, thinner and weaker with age, starts 30-40, women lose 8% per decade, men 3%; epiphyses, vertebra and jaws mostly
osteoporosis
severe bone loss, over 45, 29% of women, 18% men
osteoporosis treatment
ca, vD, fluoride supplements; weight bearing excercise, hormone replacement therapy slows loss