Bones Flashcards
Periosteum
Outer layer of bones, fibrous layer serves as a point for blood vessels and nerves to attach, cellular layer contains mesenchymal stem cells
Osteoblasts
Synthesises osteoid and then deposits calcium hydroxyapatite to form extracellular matrix of bone
Osteocytes
Osteoblasts that got stuck in the bone, monitor the bone, respond to stress levels
Osteoclasts
Destroyers, perform resorption (destruction)
Osteoid
Extracellular matrix, mostly type 1 collagen stuck together by ground substance
Osteon
Functional unit of compact bone, circular structure
Structure of osteon
Layers of rings called lamellae separated by interstitial lamella
Haversian canal
Blood vessels in the centre of osteon
Volkmann canal
Connect Haversian canals with periosteum
Endochondral ossification
Formation of long bones from cartilage template, continued lengthening is by ossification at epiphyseal plates
Intramembranous ossification
Form from clusters of mesenchymal stem cell in the centre of the bone
Cancellous bone conversion to cortical bone
- mesenchymal stem cells differentiate into osteoblasts, lay down osteoid
- Osteoblasts is trapped
- Repeat to form lamellae
- Central MSCs convert into blood vessels, lymph vessels and nerves
Appositional growth
increasing width
5 types of bones
Long, short, flat, irregular, sesamoid
Long bones
- Longer than they are wide
- Support the weight of the body and facilitate movement
Short bones
- Approximately as long as they are wide
- Provide stability and some movement
Flat bones
- Somewhat flattened with roughly parallel opposite edges
- Protect internal organs and provide large areas of attachment for muscles
Irregular bones
- Vary in shape and structure and do not fit any other category
- Protect internal organs, provide anchor points for muscle groups
Sesamoid bones
- Small, round bones found in tendons of hands, knees and feet
- Protect tendons from stress and damage from repeated “wear and tear”
Where is bone marrow found?
In spaces in cancellous bone along with blood vessels and nerves
Trebeculae in cancellous bone
Supporting beams in bone
Red bone marrow
Full of developing RBC, rich blood supply, only found in cancellous bone.
Function of red bone marrow
Replenish cells in blood (haemopoiesis)
Yellow bone marrow
Full of adipocytes, poor blood supply
Function of yellow bone marrow
Shock absorber and energy source, can convert to red bone marrow
Precapillary sphincters
Control flow in capillaries, located between arterials and capillaries
3 layers of veins
Tunica intima (endothelial), tunica media (elastic fibres and smooth muscle cells), tunica externa (elastic fibrous capsule)
Systemic veins
Return deoxygenated blood back to right atrium
Superficial veins
Located close to the skin, no corresponding artery
Deep veins
Located deep between tissues and typically located near a corresponding artery with same name
Tunica intima in arteries
composed of an elastic lining and smooth endothelium
Tunica media
composed of smooth muscle and elastic fibres, thicker in arteries
Tunica adventitia
Strong outer covering composed of collagen and elastic fibres, allows arteries to stretch but prevents over-expansion
Collateral circulation
Collateral vessels provide an alternative route, like a road diversion
