anatomy chapter 6

how often are bones replaced

bones are very dynamic and actively replace themselves about every 7 years

functions of the skeletal system

* support
* protection
* movement
* storage
* blood cell production (hematopoiesis)

SSM-PB

SUPPORT function of the skeletal system

* bone is hard and rigid, cartilage is flexible yet strong
* cartilage in nose, external ear, thoracic cage and trahcea
* ligaments - bone to bone

PROTECTION function of the skeletal system

* skull around brain
* ribs, sternum, vertebrae protect organs of thoracic cavity

MOVEMENT function of the skeletal system

* produced by muscles o bones, via. tendons
* ligaments allow some movement between bones but prevent excessive movement

STORAGE function of the skeletal system

* Ca and P; stored then released as needed
* adipose tissue stored in marrow cavities

BLOOD CEL PRODUCTION (HEMATOPOIESIS) function of the skeletal system

* bone marrow that gives rise to blood cells and platelets

how many bones in body

\~206

3 ways skeleton is divided

* location (axial vs. appendicular)
* shape (long, short, flat, irregular)
* internal structure (compact and spongy)

axial

bones along the vertebral axis (skull, vertebral column, and rib)

appendicular

limbs and what the limbs use to attach to the axial bones (pelvis, shoulder blades, arms, and legs)

long bones

ex. upper and lower limbs

* femur/thigh

short bones

ex. carpals and tarsals

flat bones

* ribs, sternum, skull, scapulae

irregular bones

ex. vertebrae, facial

compact bone

* har, smooth bone

spongy bone

* light, softer, porous bone

compact bone in flat, short, and irregular bones

* hard exterior
* surfaces
* organized in lamellae

spongy bone in flat, short, and irregular bones

* softer interior (porous)
* like a sandwich
* organized in trabeculae

compact bone in long bones

* hard exterior
* external surface and diaphysis (middle)
* organized in lamellae

spongy bone in compact bones

* softer interior (porous)
* concentrated more in epiphysis (ends)
* organized in trabeculae

compact bones contain

* lamellae
* central canals
* osteocytes
* osteons

lamellae

concentric rings that run in opposite directions for strength

central canals

parallel to long axis, hold nerves and blood vessels

osteocyte

bone cells

osteon

central canal, contents, associated concentric lamellae and osteocytes

trabeculae

* organization of spongy bone
* interconnecting rods or plates of bone. like scaffolding
* spaces filled with marrow

bone cells

* osteocytes
* osteoblasts
* osteogenic
* osteoclasts

osteocytes

* mature bone cells
* make small mount of bone, but mostly just maintain bone
* lacunae: spaces occupied by osteocyte cell body

lacunae

spaces occupied by osteocyte cell body

osteoblasts

formation of bone through ossification or osteogenesis

ossification

format ion of bone by osteoblasts

osteogenic

(osteoprogenitor) - stem cells that can turn into any osteo cell

osteoclasts

resorption of bone

mechanical stress and bone strength

* stress causes bone remodeling to
* increase bone mass (density)
* align trabeculae with stress
* changes causes by:
* osteoblast activity
* increases with stress

bone remodeling

* converts fetal or damaged into lamellar bone
* groups of osteoclasts and osteoblasts that remodel bones
* involved in bone growth, changes in bone shape, adjustmets in bone due to stress, bone repair, and Ca ion regulation

formation of new osteons in compact bone

* osteoclasts enter the osteon from blood in the central canal and iternally remove lamellae.
* osteoclasts remove bone from the exterior, and the bone is rebuilt

calcium homeostasis

* ca+ is used for several psychological processes
* muscle contractions
* nerve signaling
* salt that is used in bone formation

major storage site for calcoum

* bone; like our bodies calcium “bank”
* blood calcium depends upon movement of calcium in or out of bone
* calcium enters bone when osteoblasts build new bone. calcium leaves bone when osteoclasts resorb bone

two hormones that control blood calcium levels

* parathyroid hormone
* calcitonin

calcium __ bone when osteoblasts new bone

enters

open (compound)

bone break with open wound. bone may be sticking out of wound

closed (simple)

skind not perforated

incomplete/hairline

doesn’t extend across the bone. common in skull fractures

comminuted fractures

complete with break into more than two pieces

impacted fractures

one fragment is driven into the spongy portion of the other fragment

* classified on the basis of direction of fracture
* linear
* transverse
* spiral
* oblique
* greenstick