A&P CH 7: Bones

What are the functions of bones?

• maintain shape

• support

• protection

• movement

• electrolyte balance

• blood prod

• acid base balance

What are the classifications of bones?

1. flat

2. short

3. long

4. irregular

What are the major cells found inside bone?

1. osteoBlasts

2. ostepClasts

3. osteoCytes

What are osteoBlasts?

cells that help form bone

What are osteoClasts?

cells that help dissolve old + unwanted bone

What are osteoCytes?

they are mature osteoBlast cells embedded in hardened bone matrix

What are the functions of osetoCytes?

• sense mech stressors + chem changes

• prompt osteoBlasts + osteoClasts to begin bone remodels or repair → which helps maintain bone density

• assists w reg of calcium + phosphate

What are the characteristics of bone?

• hard + calcified matrix

• highly resis to stretching forces → tensile strength

• resis to squuezing factors → compressional strength

• LACKS ability to resist twisting → torsional strength

What are the factors affecting bone growth?

• heredity

• nutition

• horms

• exercise

What are the types of bone tiss?

1. compact bone

2. spongy (cancellous) bone

What is compact bone?

forms the shafts of long bones + surfs of most other bones

What is spongy bone?

found in the ends of long bones + middle of other bones

What are the types of bone marrow?

• red marrow= prods RBCs

• yellow marrow= saturated w fat

How does bone develop?

ossification= the creation of new bone

Intramembranous ossification

oss of fibrous connec tiss (skull + face)

What is endochondrial ossification?

oss of new cartilage (long bones)

• proc in the fetus whereby the cartilaginous skel transforms into bone

Where + when does bone growth occur?

• bone lengthening occurs at the epiphyseal plate for a fixed period

• bone widening continues t/o the life span

What are the parts of a long bone?

• epiphysis

• diaphysis

• articular cartilage

• medullary cavity

• endosteum

• bone marrow

• periosteum

What is bone remodeling?

a proc in which bone cells continually destroy old bone (resorption) + deposit new bone (ossif)

What is the life cycle of bone remodeling?

• childhood → bone creation (ossif) outpaces resorp

• middle adulthood → creation + resorp in balance

• after age 40 → bone loss incs + formation slows, causing bones to weaken

What are the main types of bone fractures?

1. simple

2. compound

3. greenstick

4. comminuted

5. spiral

Simple fracture

bone remains aligned + surrounding tiss intact

Compound fracture

the bone pierces the skin in break

Greenstick fracture

incomplete fracture → not all the way across bone

Comminuted fracture

bone breaks into mult pieces

Spiral fracture

fracture line spirals vert around the bone → the result of a twisting force

What are the steps of fracture repair?

1. initial hematoma transforms into granulation tiss

2. granulation tiss transforms into a soft callus

3. a hard callus forms around the fracture

4. remodeling replaces the callus tiss w bone

Parts of a spongy bone?

• periosteum

• trabeculae

Parts of compact bone

• osteon

• haversian canal

• lamellae

• lacunae

• caniculi

• Volkmann’s canal

Periosteum

dense fibrous memb covering the diaphysis

Trabeculae

lattice work of osseous tiss that makes up the struc of spongy/cancellous bone

Diaphysis

the central shaft like portion of a long bone

Osteon

basic struc unit of compact bone consisting of a haversian canal + surrounding lamellae

Lamellae

concentric rings of matrix surrounding haversian canal in compact bone

Lacunae

tiny gaps btwn rings of lamellae in compact bone

Canaliculi

microscopic passageways that connect lamellae to each other

Volkmann’s canal

transverse passageways found in compact bone, connect the Haversian canals

Haversian canal

a central canal in compact bone containing blood vess + nerves, surrounded by lamellae

Epiphysis

the head on each end of a long bone

• contains epiphyseal plate in developmental years

Epiphyseal plate

layer of cartilage separating the epiphysis from the diaphysis at each end of the long bone'

• the site where bone growth occurs

Endosteum

a thin epithelial memb lining the inside of the medullary cavity in a long bone

Medullary cavity

the central hollow portion of a long bone that contain the bone marrow

Articular cartilage

a thin layer of hyaline cartilage covering the surf of the epiphysis in long bones

What is the basic structural unit of bone?

osteon

A fetus’s skel is mostly composed of?

cartilage