chapter 7 bone structure anatomy and physiology 1

functions of bone

support(structural support and provide framework for soft tissue)

mineral storage(calcium and phosphorous)

storage of lipids(yellow marrow)

blood cell production(red marrow)

protection(ribs, skull, vertebra)

leverage(force of motion)

1. long bones

long and thin, commonly broken bones

examples of where long bones are

found in arms, legs, hands, and feet

2. flat bones

thin with parallel surfaces

examples of where flat bones are

found in skull, sternum, ribs, and scapula

3. sutural bones

small, irregular bones

examples of sutural bones are

found between flat bones of skull

4. irregular bones

complex shapes

examples of irregular bones

spinal vertebrae, pelvic bones

5. short bones

small and thick

examples of short bones

ankle and wrist bones

6. sesamoid bones

small and flat

examples of sesamoid bones are developed

inside tendons near joints of knees, hands, and feet(patella is example)

foramen (depression)

opening

fossa (depression)

shallow depression

sulcus (depression)

groove

meatus (depression)

canal

fissure (depression)

slit

sinus (depression)

cavity (sign of infection)

condyle (processes)

rounded knuckle

tuberosity (processes)

large rough process

tubercle (processes)

small rounded process

trochanter (processes)

very large process

head (processes)

supported by a neck

crest (processes)

narrow ridge

spine (processes)

sharp, slender process (ischial spine is example

epiphysis

wide part at each end, mostly spongy bone, articulation with other bones

diaphysis

the shaft, a heavy wall of compact bone, a central space called marrow cavity

metaphysis

where diaphysis and epiphysis meet, epiphyseal line (bone growth)

endosteum

inner layer of compact bone, lines medullary cavity (where marrow is), covers trabeculae of spongy bone

periosteum

covers outer layer of bones, EXCEPT parts enclosed in joint capsules, made up of outer fibrous layer and inner cellular layer

functions of periosteum

1. isolate bone from surrounding tissues

2. provide a route for circulatory and nervous supply

3. participate in bone growth and repair

articular cartilage

hyaline cartilage covering that prevents bone-to-bone contact in joints

2/3 of weight of bones

calcium and phosphate

1/3 of bone is made of

protein fibers(collagen)

osteoprogenitor cells

stem cells→ osteoblasts

osteocytes cells

mature bone cells, maintain protein and mineral content of bone, DO NOT divide

osteoblasts cells

produce new bone matrix (osteogenesis-start)

osteoid cells

organic matrix for calcium salt deposit, matrix produced by osteoblasts, not calcified

osteoclasts cells

remove or recycle bone matrix(osteolysis)

secrete acids and protein-digestive enzymes

osteon (part of compact bone)

basic unit of mature compact bone, osteocytes are arranged in concentric lamellae

lamellae (part of compact bone)

layers of matrix

canaliculi (part of compact bone)

form pathways for blood vessels, exchange nutrients and wastes around central canal containing blood vessels

perforating canals

perpendicular to central canal, carry blood vessels into bone and marrow

spongy bone

does not have osteons, matrix forms and open network of trabeculae (no blood vessels)

red marrow

forms red blood cells

yellow marrow

is yellow because it stores fat (adipose tissue)

ossification

the process of replacing other tissues with bone

endochondral ossification

intramembranous ossification

what age do bones grow until?

25

calcification

process of depositing calcium salts, occurs during bone ossification and in other tissues(tendons and ligaments)

homeostasis is maintained by

bone building(osteocytes) and bone recycling(osteoclasts)

1. step of endochondral ossification

chondrocytes in center of hyaline cartilage

-enlarge

-form struts and calcify

-die, leaving cavities in cartilage

2. step of endochondral ossification

blood vessels grow around edges of cartilage, cells in perichondrium change to osteoblasts

provides layer of superficial bone around shaft, continues growing and becoming compact bone

3. step of endochondral ossification

blood vessels enter cartilage

bring fibroblasts that become osteoblasts

spongy bone develops primary ossification center

4. step of endochondral ossification

remodeling creates marrow cavity

bone replaces cartilage at metaphysis

5. step of endochondral ossification

capillaries and osteoblasts enter epiphysis

creating secondary ossification centers

6. step of endochondral ossification

epiphysis fills with spongy bone

cartilage within joint cavity

articulation cartilage

cartilage at metaphysis

epiphyseal cartilage

1. step of intramembranous ossification(dermal)

-produce dermal bones(mandible and clavicle)

mesenchymal(stem) cells aggregate

-differentiate into osteoblasts

-begin ossification at ossification center

-develop projections(spicules)

2. step of intramembranous ossification

blood vessels grow into area(to supply osteoblasts)

spicules connect(trapping blood vessels) inside bone

3. step of intramembranous ossification

spongy bone develops and is remodeled into

-osteons of compact bone

-periosteum

-or marrow cavities

epiphyseal lines

when long bones stop growing, after puberity

bone remodeling

recycles and renews bone matrix, involves osteocytes, osteoblasts, and osteoclasts

dynamic nature of bone

bone continually remodels, recycles, and replaces

exercise on bones

heavily stressed bones become thicker and stronger, mineral recycling allows bones to adapt to stress

bone degradation (bank account)

happens quickly, 1/3 of body mass can be lost in a few weeks if inactivity

vitamin C

is required for collagen synthesis, and stimulates osteoblast differentiation

vitamin A

stimulates osteoblast activity

vitamin K and B12

help synthesize bone proteins

calcitriol (hormone)

is made in the kidneys

helps absorb calcium and phosphorus from digestive tract

synthesis of vitamin D3(cholecalciferol)

growth hormone

bone growth

sex hormones

osteoblasts

calcitonin and parathyroid

regulate calcium and phosphate levels

parathyroid hormones (PTH)

increase calcium ion levels by

-stimulating osteoclasts

-increasing intestinal absorption of calcium

-decreasing calcium excretion of kidneys

calcitonin hormones

decreases calcium ion levels by

-inhibiting osteoclast activity

-increasing calcium excretion at kidneys

what is the most abundant mineral in the body?

calcium

osteoporosis

severe bone loss, occurs in ages over 45

18% of men

29% of women-after menopause

fracture

cracks/breaks in the bones that is caused by physical stress

first step of fracture repair

bleeding: produces a clot, establishes fibrous network, bone cells in the area die

second step of fracture repair

bone growth stabilizes the break:

external callus of cartilage and bone surrounds the break

internal callus develops in marrow cavity

cells of endosteum and periosteum divide and migrate into fracture zone

third step of fracture repair

osteoblasts replace central cartilage of external callus with spongy bone

fourth step of fracture repair

osteoblasts and osteocytes remodel fracture for up to year

simple fracture

(closed) contained

compound fracture

(open) not contained

incomplete fracture

not broken completely through the bone

complete fracture

broken totally through the bone

greenstick fracture

(children), one side breaks and other side bends(bones less strong, spongy)

comminuted/segmental fracture

3 or more pieces breaks from the shaft(pretty bad)

transverse fracture

across bone

displaced fracture

bone moves out of alignment

oblique fracture

diagonal break of bone(angle)

spiral fracture

twisting(little kids arm=possible abuse)

compacted fracture

end of bone is driven into shaft

compression fracture

crushed or clasped vertebrae

epiphyseal fracture

along plate, can stop growth, but do heal very well

colles’ fracture

distal radius, reaching out during fall

pott’s fracture

break of both bones of the ankle