Bone Tissue

Front 1

functions of the skeleton

Back 1

support, protection, movement, electrolyte balance, acid-base balance, blood formation

Front 2

another name for bone

Back 2

osseous tissue

Front 3

calcification

Back 3

hardening process of bones(mineralization)

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shapes of bones

Back 4

long bones, short bones, flat bones, irregular bones

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shaft

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(diaphysis) cylinder of compact bone

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marrow cavity of the shaft

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medullary cavity, is lined w/ endosteum(osteogenic cells and reticular connective tissue)

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enlarged ends of bones

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epiphyses, spongy bone covered by compact bone, is enlarged to strengthen joint and attach ligament

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the joint surface of bones is____

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covered w/ articular cartilage

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nutrient foramen

Back 9

blood vessles that penetrate bone

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periosteum

Back 10

outer fibrous layer of collagen, inner osteogenic layer of bone forming cells

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endosteum

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thin layer of reticular connective tissue and osteogenic cells

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epiphyseal plate

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growth plate

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types of bone cells

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osteogenic, osteoblasts, osteocytes, osteoclasts

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bone matrix

Back 14

dry weight, 1/3 organic, 2/3 inorganic matter

Front 15

organic matter of bone matrix

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collagen, glycosaminoglycans, proteoglycans, and glycoproteins

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inorganic matter of bone matrix

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85% hydroxyapatite, 10% calcium carbonate, 5% other minerals(fluoride, potassium, magnesium)

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combination of organic and inorganic matter of bone matrix_____

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provides for strength and resilience

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minerals in bone matrix...

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resist compression

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collagen in bone matrix...

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resists tension

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osteon

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basic structural unit of compact bone

Front 21

cylinders of osteons are formed...

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from layers(lamellae) of matrix around central canal(osteonic canal)

Front 22

in osteons, collagen fibers...

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alternate between right and left handed helices from lamella to lamella

Front 23

canaliculi

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tiny cell processes that allow osteocytes to connect to each other and their blood supply

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perforating canals

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Volklmann canals, vascular canals perpendicularly joining central canals

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trabeculae

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spongelike appearance formed by plates of bone called trabeculae

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spaces of spongy bone filled w/

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red bone marrow

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trabeculae have few...

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osteons or central canals(no osteocyte is far from blood of bone marrow)

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the trabeculae provides...

Back 28

strength w/ little wieght, develop along bone's lines of stress

Front 29

bone marrow

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soft tissue that occupies marrow cavity

Front 30

this type of marrow is hemopoietic

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red bone marrow

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hemopoietic

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produces blood cells

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yellow bone marrow

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fat at center, no longer produces blood

Front 33

intramembranous ossification

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condensation of mesenchyme into trabeculae

Front 34

embryonic connective tissue

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mesenchyme

Front 35

during intramembranous ossification, osteoblasts on trabeculae...

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lay down osteoid tissue(uncalcified bone)

Front 36

during intramembranous ossification_______ is deposited in the matrix forming bony trabeculae of spongy bone

Back 36

calcium phosphate

Front 37

during intramembranous ossification, osteoclasts...

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create marrow cavity and form compact bone at surface

Front 38

during intramembranous ossification, surface mesenchyme...

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produces periosteum

Front 39

during endochondral ossification...

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bone develops from pre-existing model, most bones develop this process, formation of primary ossification center and marrow cavity in shaft of model

Front 40

during primary ossification of endochondral ossification

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bony collar is developed by osteoblasts, chondrocytes swell and die, stem cells give rise to osteoblasts and clasts, bone is laid down and marrow cavity is created

Front 41

the secondary ossification centers and marrow cavities of endochondral ossification

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form in ends of bone through same process as primary ossification centers

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the secondary ossification centers and marrow cavities of endochondral ossification cartilage...

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remains as articular cartilage and epiphyseal growth plates

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growth plates

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provide for increase in length of bone during childhood and adolescence

Front 44

by early twenties, growth plates...

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are gone and primary and secondary marrow cavities are united

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zone of reserve cartilage(bone elongation)

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hyaline cartilage

Front 46

zone of proliferation(bone elongation)

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chondrocytes multiply forming columns of flat lacunae

Front 47

zone of hypertrophy(bone elongation)

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cell enlargement

Front 48

zone of calcification(bone elongation)

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mineralization of matrix

Front 49

zone of bone deposition(bone elongation)

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chondrocytes die and columns fill w/ osteoblasts, osteons formed and spongy bone is created

Front 50

during bone growth and remodeling...

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bones increase in length, bones increase in width(appositional growth)

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bones are remodeled...

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throughout life

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bones increase in length by...

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interstitial growth of epipyseal plate, epipyseal line is left behind when cartilage is gone

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when bones increase in width...

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osteoblasts lay down matrix in layers on outer surface and osteoclasts dissolve bone on inner surface

Front 54

Wolff's law of bone

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architecture of bone is determined by mechanical stresses(action of osteoblasts and osteoclasts)

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mineralization is a....

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crystallization process

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during mineralization

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osteoblasts produce collagen fibers spiraled the length of the osteon, minerals cover the fibers and harden the matrix

Front 57

when minerals cover the fibers and harden the matrix...

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ions are deposited along the fibers; ion concentration must reach the solubility product for crystal formation to occur

Front 58

abnormal calcification

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(ectopic) may occur in lungs, brain, eyes, muscles, tendons or arteries(arteriosclerosis)

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during mineral resorption from bone...

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bone is dissolved and minerals are released into the blood

Front 60

when bone is dissolved and minerals are released into the blood...

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performed by osteoclasts(ruffled border), hydrogen pumps in membrane secrete hydrogen into space between the osteoclast and bone surface, chloride ions follow by electrical attraction, hydrochloric acid dissolves bone minerals, enzyme digest the collagen

Front 61

dental braces reposition teeth and remodel bone

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create more pressure on one side of the tooth, stimulates osteoclasts to remove bone, decreased pressure stimulates osteoblasts

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Phosphate is a component of ...

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DNA, RNA, ATP, phospholipids, and pH buffers

Front 63

how much phosphate in adult skeleton

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750g

Front 64

plasma concentration of phospate

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4 mg per dL

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calcium is needed in ...

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neurons, muscle contraciton, blood clotting and exocytosis

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how much calcium in adult skeleton

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1100g

Front 67

plasma concentration of calcium

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10mg per dL

Front 68

ion imbalances in the bones are caused through...

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changes in phosphate levels(little effect) and changes in calcium levels(can be serious)

Front 69

hypocalcemia

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deficiency of blood calcium, causes excitability of nervous system if too low(muscle spasms, tremors)

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hypercalcemia

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excess of blood calcium, binding to cell surface makes sodium channels less likely to open, depressing nervous system(muscle weakness and sluggish reflexes)

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calcium phosphate homestasis...

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depends on calcitriol, calcitonin, and PTH hormone regulation

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carpopedal spasm

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hypocalcemia demonstrated by muscle spasm of hands and feet

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calcitriol, PTH, and calcitonin...

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maintain normal blood calcium concentration

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calcitriol

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activated vitamin D, behaves as a hormone that raises blood calcium concentration

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calcitriol is produced by the following process

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UV radiation and epidermal keratinocytes convert steroid derivative to cholecalciferol(D3), liver converts it to calcidiol, kidney converts that to calcitriol(Vitamin D)

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calcitriol behaves as a gromone that raises blood calcium concerntration by....

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increasing intestinal absorption and absorption from the skeleton, increases stem cell differentiation into osteoclasts, promotes urinary reabsorption of calcium ions

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lack of calcitriol causes...

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abnormal softness(rickets) in children and osteomalacia in adults

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calcitonin

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secreted(C cells of thyroid gland) when calcium concentration rises too high

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functions of calcitonin

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reduces osteoclast activity as much as 70%, increases the number and activity of osteoblasts, reduces bone loss in osteoporosis

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calcitonin is important in children

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because osteoclasts are more active in children

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deficiency of calcitonin does not

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cause disease in adults

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Parathyroid hormone

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released w/ low calcium blood levels, glands located on posterior surface of thyroid

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function of PTH

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causes osteoblasts to release osteoclast-stimulating factor(RANKL) increasing osteoclast population, promotes calcium resorption by the kidneys, promotes calcitriol synthesis in the kidneys, inhibits collagen synthesis and bone deposition by osteoblasts

Front 84

sporatic injection of low levels of PTH

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causes bone deposition

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other factors affecting bones

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hormones, vitamins, growth factors

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bone growth is_____during puberty and stops when_______ closes

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rapid, epiphyseal plate

Front 87

during the growth rate at puberty

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hormones stimulate osteogenic cells, chondrocytes, and matrix deposition in growth plate

Front 88

teenage use of anabolic steroids causes

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premature closure of growth plate and short adult stature

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pathological bone fracture

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in bone weakened by disease(osteoporosis, bone cancer)

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types of bone fractures

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open, greenstick, comminuted, linear, transverse, oblique, spiral, colles, pott

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healing time of fractures

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8-12 weeks in normal adults

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stages of bone healing

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fracure hematoma, soft callus, hard callus, remodeling

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fracture hematoma

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clot forms, then osteogenic cells form granulation tissue

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soft callus

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fibroblasts produce fibers and fibrocartilage

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hard callus

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osteoblasts produce a bony collar in 6 weeks

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remodeling

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spongy bone replaced by compact bone

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closed reduction

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fragments are aligned w/ manipulation and casted

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open reduction

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surgical exposure and repair w/ plates and screws

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electrical stimulation used on fractures...

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if 2 months necessary for healing

Front 100

orthopedics

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prevention and correction of injuries and disorders of the bones, joints, and muscles

Front 101

osteoporosis

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bones lose mass and become brittle(loss of organic matrix and minerals), risk of fracture, pneumonia, blood clotting

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greatest risk to osteoporosis

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menopausal white women

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osteogenic cells

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stem cells that develop from fibroblasts and then give rise to other bone cells

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osteoblasts

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bone forming cells

Front 105

osteocytes

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former osteoblasts that have become trapped in the matrix they deposited

Front 106

osteoclasts

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bone dissolving cells found on the bone surface