bone composition

function of the skeleton

support

protection

movement

mineral homeostasis

haematopoiesis

energy storage

what is mineral homeostasis?

calcium and phosphate storage

99% of body’s calcium is contained within bones

haematopoiesis

red bone marrow

• medulla ossium rubra

energy storage

yellow bone marrow

• medulla ossium flava

types of bones

bones are classified based on shape

what is the composition of bone?

inorganic components - stiffness

• mineral hydroxyapatite crystals

• calcium, carbonate, phosphate

organic component - flexibility and strength

• organic matrix

• collagen type 1

cells

• promote and help maintain mineral density and content

other components

• water

• lipids

characteristics of trabecular/spongy bone

makes 20 percent of long bone

located inner side of bone

spongy

high surface area to mass ratio

softer, weaker, more flexible

composition of trabecular/spongy bone

highly vascular

space is filled by red bone marrow

lamellae are arranged in irregular latticework → trabeculae

characteristics of compact/cortical bone

makes 80 percent long bone

outer side of bone

compact and strong

does not have spaces or hollows visible to the eye

composition of compact/cortical bone

has unique concentric arrangement of haversian system → osteon

label long bone

components of osteon

haversian canal (HC)

• contains blood vessels and nerves

concentric lamellae

• concentric arrangement of collagen fibres

• surrounds the haversian canal

• osteocytes send out protrusions through canaliculi to communicate through blood vessels