bone structure Flashcards
long bone has two parts
- diaphysis
- epiphysis
diaphysis
- tubular shaft
- runs between proximal and sitar ends of bone
- hollow region: medullary cavity; filled with yellow marrow
- walls are composed of dense and hard compact bone
epiphysis
- wider section at each bone
- filled with spongy bone
- red marrow fills the spaces in spongy bone
what is the metaphysis in a bone
narrow area where the epiphysis meets the diaphysis and contains the epiphyseal plate (growth plate) in a growing bone
what happens to the epiphyseal plate when a bone stops growing?
- bone growth stops around 18-21
- epiphyseal plate is replaced by osseous tissue=becoming the epiphyseal line
what is the endosteum and what is its function
delicate membranous lining inside the medullary cavity where bone growth, repair and remodelling occur
what is the periosteum and what does it do
-fibrous membrane covering outer surface of bones except at joints
- contains blood vessels, nerves, lymphatic vessels that nourish compact bone and serve as an attachment point for ligaments and tendons
role of articular cartilage in bone joints?
- thin layer covering epiphyses where bones form joints
- reducing friction
- shock absorber
what is the diploe? (hint- flat bone like the cranium, how do they protect internal organs?)
- flat bones consist of a layer of spongy bone ; diploe : between two layers of compact bone
- this helps protect internal organs even if the outer layer fractures, the brain remains protected by the intact inner layer
what is the role of collagen fibres in bone
provide a surface for inorganic salt crystals to adhere to give bones flexibility, preventing them from being brittle
what are hydroxyapatite crystals and their role in bone
- made from calcium phosphate, calcium carbonate and other inorganic salts form on collagen fibres and give bones their hardness and strength
how much bone volume is composed of bone cells?
small amount of bone volume but crucial to its function
4 types of bone cells?
- osteoblasts
- osteocytes
- osteogenic cells
- osteoclasts
osteoblasts
- form new bone by synthesizing and secreting the collagen matrix and calcium salts
- found in growing bone areas like the periosteum and endosteum
what happens to osteoblasts as the bone matrix calcifies?
as bone matrix calcifies around osteoblasts, they become trapped and transform into osteocytes, the primary cell of mature bone
function of osteocytes in bones?
maintain the mineral concentration of the bone matrix and receive nutrients and help communicate with other osteocytes through long cytoplasmic processes extending through canaliculi channels within the bone matrix
osteogenic cells
- only bone cell that divides
- immature osteogenic cells are found in deep layers of periosteum and the marrow
- differentiate and develop into osteoblasts
what bone cell is responsible for bone reabsorption or breakdown?
osteoclasts
osteoblasts
- found on bone surfaces
- multinucleated
- originate from monocytes and macrophages
- break down old bone and form new bone
which cells help reshape bone
osteoclasts and osteoblasts
what is compact bone
- denser, stronger of the two types of bone tissue
- can be found deep in periosteum and in diaphyses of long bones where it provides protection and support
what is basic structural unit of compact bone?
- called an ‘osteon’ or Haversian system
what are lamellae in bone
concentric rings of calcified matrix that make up the osteon
function of the central Haversian canal in an osteon
central canal contains blood vessels, nerves and lymphatic vessels that supply the bone
