Part A: Microscopic structure of compact bone

central (haversion) canal

• tubes in compact holding blood vessels and nerve fibers

• allows bones to get oxygen nutrients

lacunae

• space housing osteocytes in bone, between lamellae

• keeps osteocytes alive and functional

osteocytes

• mature bone cells

  • maintains bone metabolism bgy acquiring nutrients & eliminating wastes

concentric lamellae

• rings of ECM surrounding osteonic canal

• structural unit of compact bone; strength and support

canaliculi

• small channels permitting communication between lacunae and exchange of nutrients and wastes w/ osteonic canals

trabeculae

• structural units in SPONGY BONE TISSUE

• bone lamellae arranged in a network of thin projections arranged along stress lines

  • makes bone lighter; easier to move

how do osteoblasts, osteoclasts, and osteocytes work together to maintain the skeletal system?

• osteoblasts → secrete collagen & other components of bone ECM; bone deposition

  • they eventually get submerged in their secretions and become….

• osteocytes → maintain bone metabolism by acquiring nutrients and eliminating wastes

• osteoclasts → break down old bone to make room for new bone; maintains health/quality

4 areas in the skeleton where spongy bone tissue is found.

1. end of long bones

2. skull

3. ribs

4. vertebrae

where do osteocytes of spongy bone get nutrients and oxygen since there is no haversian canal?

• yellow or red bone marrow betwen trabeculae contains blood vessels that deliver nutrients

  OR

• diffusion along canaliculi that open unto surfaces of trabeculae

compare red and yellow bone marrow of spongy bone tissue

• red → produces blood cells

• yellow → adipose tissue (cushioning, stores energy, insulation)

name 4 adult bones that contain red bone marrow

1. hip bones

2. ribs

3. vertebrae

4. skull

epiphysis (proximal & distal)

• ends of long bone

  • connects bones to form joints

diaphysis/shaft

• long, cylindrical middle/main part of the bone

  • structure, transport of oxygen, mineral & fat storage

periosteum

• CT sheath; blood supply that surrounds the bone surface where it is not covered by articular cartilage

• composed of outer fibrous lahyer of dense irregular CT and an inner osteogenic layer consisting of osteoprogenitor cells

• attached to bone by perforating fibers

• protects the bone, fracture repair, nourishes, attachment point for ligaments and tendons

endosteum

• thin membrane that lines the medullary cavity and the internal spaces of spongy bone

• bone growth, repair, remodelling; contains osteoprogenitor cells and some CT

medullary cavity

• hollow, cylindrical space within diaphysis that contains fatty yellow bone marrow and blood vessels

  • minimizes weight; reduces dense material

epiphyseal line/plate

• “growth plate”; thin layer of hyaline carilage that sits between the epiphysis and metaphysis

• site of longitudinal growth of long bones

4 functions of the skeletal system

1. protects internal organs

2. stores and releases minerals

3. contains red bone marrow → blood cells

4. works tgt w/ skeletal muscles to allow movement