chapter 7 bone tissue

osteology

study of the bone

ligaments hold bones together

tendons attach muscle to bone

hypochondria

below/cartilage

flat bones

skull

long bones

humerus , radius , ulna , femur , tibia , vertebrae

humerus

proximal lateral

radius

distal lateral

ulna

medial

femur

proximal

tibia

medial distal

Spongy (cancellous) bone

loosely organized , porous , trabechulae , redbone marrow

diaphysis

shaft in middle of bone , 1 for every long bone , compact only

epiphysis

end of long bone , 2 for every long bone , spongy only

periosteum

around the hone (perimeter),

endosteum

marrow cavity, thin lining of reticular connective tissue

sandwich

flat bones have a have a sandwich like structure , enclosing layer of spongy bone in between (called diploe in cranium), in skull

trabeculae

spongy bone

osteoblasts

rule of B’s : builds bone, calcium levels drop bc calcium is being used to build bone

osteogenesis

osteoblasts, bone formation

exercise

stress stimulates osteogenic cells to reinforce bone

osteoclasts

resorb, bone dissolving , calcium levels raise because of dissolved bone

osteolysis

osteoclast, bone remodeling

resorption

breakdown of bone, osteoclast

remodeling

osteoblasts + osteoclast

concentric lamellae

layers

Circumferential lamellae

circumference of entire bone

lacunae

tiny cavities (blasts and clasts)

canaliculi

channels that connect lacunae

sponge like appearance

trabeculae , spaces filled with red bone marrow , blood formation

hematopoietic

blood forming

red bone marrow

i’m every bone of a child , adults axial skeleton only

yellow bone marrow

appendicular extremities , only in adults

Intramembranous ossification

skull/ flat

Endochondral ossification 1

hyaline cartilage

Endochondral ossification 2

primary ossification center in the diaphysis of bone

Endochondral ossification 3

vascular invasion, arrival of blood vessels bringing oxygen making atp

Endochondral ossification 4

secondary ossification center, epiphysis

Endochondral ossification 5

active chondrosites, epiphyseal plate = growth

Endochondral ossification 6

adult bone with a single marrow cavity and closed epiphyseal plate

Achondroplastic dwarfism

without cartilage formation , normal torso , short limbs , Failure of cartilage

pituitary dwarfism

normal proportions no stimulation

Wolff’s law of bone

remodeling, stretching bone to make it grow

mineral resorption

breakdown, osteoclasts, secretes hydrochloric acid (pH 4) dissolves bone minerals releasing to blood

calcium

needed for muscle contraction

hypocalcemia

calcium deficiency

hypercalcemia

calcium excess, rare to have too much

calcitrol

vitamin d → kidney , raises calcium levels

calcitonin

produced by thyroid , lowers calcium levels activating osteoblasts

parathyroid hormone

raises calcium levels , secreted by parathyroid gland m activating osteoclasts

regulate calcium in all 3

1 bone 2 digestive tract 3 kidneys

3 ways calcitrol raises blood calcium

small intestine, increase calcium resorption from skeleton (stimulate formation of new osteoclasts)

children (rickets) and adults (osteomalacia)

inadequate calcitrol results in abnormal softness of bones

Lowers blood calcium concentration in two ways

calcitonin, thyroid , osteoblast stimulation and osteoclast inhibition

synergistic

parathyroid hormone/ calcitrol

stress fracture

abnormal trauma

pathological fracture

weakened by disease such as bone cancer or osteoporosis

nondisplaced

alignment preserved (fracture)

displaced

alignment disrupted

comminuted

shattered (gunshot)

greenstick

incomplete fracture , common in children

hematoma formation

blood clot granulation , initial healing

soft callus formation

cartilage formation / arrival condrocytes, collagen

hard callus formation

osteoblasts arrive

bone remodeling

osteoclasts activate

osteopenia

measurable decline , loss of muscle , lack of exercise

osteoporosis

greater than 30% bone loss