bone unit

Function of bone

Support body, release WBC, protect organs, shape body, movement

Hematopoesis

Blood cell creation in red bone marrow

Red bone marrow

Where hematopoesis occurs, spongy bone for adults, everywhere for infants

Yellow bone marrow

Fat storage, can change back into bone marrow

Bone structure

Connective tissue forming a matrix from calcium, salts, collagen

Calcitonin

Decreases blood calcium

Parathormone

Increases blood calcium

Bone marrow biopsy

Removes tissue from body to examine, monitor, or treat certain conditions

Epiphysis

Each end of long bone

Diaphysis

Midpoint of long bone

Articular cartilage

Smooths out head movement in a ball + socket joint, minimizes friction

Periosteum

Outer layer of bone, rich in nerves

Compact bone

Strong dense matrix

Compact bone location

Walls of diaphysis, thin surface of epiphysis

Spongy bone

Mostly in epiphysis, small amount lining epiphysis, honeycomb-like

Epiphyseal plate

Growth plate

Medullary Cavity

Stores yellow bone marrow in adults

Endosteum

Lines medullary cavity, stores red + yellow bone marrow in infants

Structure for other bone types

Thin plates of compact bone, spongy inside, no diaphysis and epiphysis, marrow between trabeculae

Osteons

Compact bone, cylinder shaped units, oriented longitudinally

Central Canal (Haversion Canal)

Longitudinal Canal

Lamella

Layers of matrix (rings)

Lacuna

Smaller chamber within matrix

Osteocytes

Mature bone cells in lacuna

Canaliculus

Transverse tube, nutrient transport between osteocytes

Ossification

Formation of bone tissue

Osteoblasts

Bone building cells, create matrix

Osteoclasts

Erodes (breaks down) matrix

Intramembranous Ossification

Flat bones - Frontal, parietal, temporal, occipital

Endochondral Ossification

All other bones in infant skeleton

Increases calcium absorption

Vitamin D

Increases growth + development

Vitamin A + C

Human Growth Hormone (HGH)

continues osteoblast mitosis at epithelial plate

Testosterone + Estrogen

Stimulate osteoblast activity

Physical stress

Stimulates epithelial plate by stretching

Fractures

Break in bone

Traumatic cause for fractures

Due to injury

Pathological cause for fractures

Due to underlying disease

Open fracture

Broken skin

Closed fracture

Severe but no broken skin

Complete fracture

Full break across the bone

Incomplete fracture

Bone partially breaks across

Greenstick traumatic fracture

Incomplete transverse fracture

Fissured traumatic fracture

Incomplete longitudinal fracture (crack in bone)

Comminuted traumatic fracture

Multiple complete fractures, creating fragments

Transverse traumatic fracture

Complete transverse fracture

Oblique traumatic fracture

Complete angled fracture

Spiral traumatic fracture

Complete twisted fracture, due to severe twisting of limb

Part 1 of healing fractures

Bleeding occurs when bone breaks, hematoma (blood clot) forms within hours

Part 2 of healing fractures

Callus (cartilage) forms, osteoblasts ossify callus, osteoclasts reabsorb extra bone

Osteoporosis

Condition where bone is weakened due to loss of calcium

Severity of Osteoporosis

Osteoporenia → Osteoporosis

Symptoms of Osteoporosis

Increased risk for fractures

Statistics for Osteoporosis

1:6 white women, less likely in Africans + Asians, increases after menopause, ½ risk for men than women

Causes for Osteoporosis

Low calcium diet, lack of physical activity, declining hormone levels, alcohol, smoking, genetics

Prevention of Osteoporosis

Calcium supplements, physical exercise, bone mineral X-ray at 65 y/o

Syndesmosis

FIbrous joint, connected by ligament, semi-movable

Suture

Fibrous joint, thin ligament connecting bones, immovable

Gomphosis

Fibrous joint, ligament holding teeth in sockets, immovable

Synchondrosis

Cartilagenous joint, temporary, epihyseal plates, immovable

Symphysis

Cartilagenous joint, cartilage between bones, semi-movable

Synovial joints

Freely movable, most joints are synovial

Joint capsule

2 layers: Outer dense connective tissue, synovial membrane

Joint cavity

Space created by synovial membrane

Synovial fluid

Secreted by synovial membrane, moistens + lubricates joint, provides nutrients to cartilage

Bursae

Fluid + fat filled sacks, cushion joint protecting tendons from sharp edges

Ligaments

Connect bones to bones, reinforce capsule

Menisci

Disks of cartilage in knee

Ball + Socket

Most mobile, shoulder + hip

Gliding

Flat surfaces sliding past each other, posterior carpals and tarsals

Hinge

One-directional movement, knee, elbow, interphalangeal

Pivot

One bone pivots around another, forearm, dens

Saddle

First metacarpal/carpal ONLY

Condyloid

Condyle on one fits cavity of another, metacarpal/phalageal, knee