Anatomy Chapter 7 Bone

functions of skeletal system

support, protection, movement, electrolyte balance, acid base balance, blood formation, hormone secretion

4 types of bones

long, short, flat, irregular

diaphysis

middle region of bone, wall of compact bone, marrow cavity with yellow marrow - adipose tissue

epiphysis

wide part at end of bones, spongey bone, articular hyaline cartilage

endostuem

inner lining of compact bone and covers spongy bone

long bone covering

periosteum, dense irregular connective tissue

structure of flat bones

spongy bone between two layers of compact bone

diploe

spongy bone in cranium

osseous tissue

name of bone tissue

osteoid

organic bone matrix

osteogenic cell

bone stem cell

osteoblast

immature cell that makes more osteoid matrix

osteocyte

mature bone cell not longer dividing or secreting matrix

osteoclast

stem cells with multiple nuclei and ruffled border, take away bone via enzyme

organic component of matrix

collagen, 1/3 of bone, gives flexibility without breaking

inorganic component of matrix

hydroxyapetites, calcium and phosphate, 85%, gives hardness and resistance

circumferential lamellae

layers of matrix around the circumfrence

interstitial lamellae

layers of matrix between osteons

perforating canal

brings blood to or between osteons

perforating fibers

collagen fibers that dig deep into bone matrix, anchor

canaliculi

connect central canal to osteocytes

osteon

functional unit of compact bone

spongy bone features

spicules and trabeculae, endosteum lines, trabeculae arranged to shift forces down

bone marrow

soft tissue occupying marrow cavities

red bone marrow

hematopoietic tissue that produces red blood cells

yellow bone marrow

fatty marrow that does not produce blood

ossification, osteogenesis

formation of bone

intramembranous ossification

mesenchymal tissue gets arranged to osteoblasts, osteoid tissue is calcified and osteocytes entrapped, honeycomb of spony bone develops, bone remodeling to form compact bone at surface

endochondrol ossification

early cartilage model, chondrocytes grow and calcify matrix into periosteum, primary ossification center forms, blood vessels invade with osteoclasts, secondary ossification center forms in epiphysis, osteoblasts replace cartilage with bone, epiphyseal plate stays between middle and end to allow for growth, epiphyseal line when growth stops

interstitial growth

growth in length, cartilage grows into epiphysis, cartilage is replaced in diaphysis side, no more growth when there is no more hyaline cartilage

appositional growth

growth in width, intramembranous ossification, collaborative process between osteoblasts and osteoclasts

wolff’s law

architecture of bone is determined by mechanical stress placed on it

mineral deposition, mineralization

crystallization, ions are taken from blood and deposited in bone

mineral resorption

dissolving bone and releasing minerals into blood

osteoporosis

when bone resorption is higher than bone deposition

hypocalcemia

lower levels of calcium in blood, hyperexcitability

hypercalcemia

higher levels of calcium, can’t contract muscles, calcium deposits in blood and kidneys

calcitonin

released when blood calcium is high, from thyroid gland, deposition of calcium into bones, kidney filtration to let extra calcium leave through urine

parathyroid hormone, calcitrol

released when blood calcium is low, from parathyroid, stimulates osteoclasts to eat away at bone, kidneys do not let calcium get filtered out

estrogen, testosterone

sex hormones that stimulate osteoblast activity

growth hormone, insulin, growth factors

stimulate bone and cartilage growth

stress facture

break caused by trauma

pathological fracture

break caused by disease weakening bone first

fracture healing

hematoma, blood vessels bring chondrocytes and fibroblasts, soft callus forms from fibrocartilage, spongy bone hard callus, bone remodeling into compact bone, thickening at break site