Session 12 Body Logistics BONE Flashcards
(38 cards)
Name the two types of ossification
- ENDOCHONRAL Ossifcation
- INTRAMEMBRANOUS Ossification
WHAT ARE THE DIFFERENCES BETWEEN THE TWO TYPES OF OSSIFICATION?
-ENDOCHONDRAL OSSIFICATION- the formation of bone from a cartilage template
-Lengthening of bones via further ossification at their EPIPHYSEAL GROWTH planes
- Involves LONG bones of the body eg ribs and limbs ( most bones of the body)
INTRAMEMBRANOUS OSSIFICATION- Directly from MESENCHYMAL TISSUE ( condensations of mesenchymal tissue)
- You also have intramembranous ossification occuring at the long bones - contributes to thickening of long bone at periosteal surface (appositional growth)
- Involves Flat bones - eg Skull, Scapula, Pelvis and Clavicle
DESCRIBE THE TWO DIFFERENCES BETWEEN THE TWO TYPES OF OSSIFICATION
- Endochondral ossification-hyaline cartilage template for ossifcation (long bones- ribs, limbs
- Intramembranous ossification-condensation of mesenchymal tissue no cartilage (flat bones- clavicle, scapula, skull, pelvis -seen in long bones for thickening )
GIVE EXAMPLES OF FLAT BONE FORMED BY INTRAMEMBRANOUS OSSIFICATION
- Skull ( temporal, mandible, maxilla, parietal , occipital, frontal)
- Clavicle ( medial end - endochondral and lateral -intramembranous)
- Scapula ( have some peripheral cartilage therefore some E.oss)
- Pelvis ( have some E.oss possibly)
WHAT IS THE FIRST BONE TO BEGIN OSSIFCATION AND THE LAST TO FINISH OSSIFYING?
- Clavicle
- Growing up to age 25 in some males.
DESCRIBE THE 5 STAGES OF INTRAMEMBRANOUS OSSIFICATION
- Small cluster of MSCs form a NIDUS (Tight cluster of cells)
- MSCs become Osteoprogenitor cell ( each cell increase develop GA and RER)
- 3.Osteoprogenitor cell—> Osteoblasts and lay down ECM with T1 Coll
- 4.Osteoid mineralised form rudimentary bone tissue SPICULES - that are surrounded by osteoblasts and contain OSTEOCYTES
- SPICULES join to form TRABECULAE which is finally replaced by lamellae of mature spongy bone
WHAT HAPPENS WHEN A SPICULE IS FORMED?
OSTEOCYTES, OSTEOBLASTS AND OSTEOCLASTS remodel i in the same way regardless if the initial ossification was endochondral or intramembranous
Name and state the function of the three specialised bone cells
- Osteocytes - Osteoblasts trapped in new osteoid - still living
- Osteoblasts- Deposit new osteoid
- Osteoclasts- Resorb bone and sit in the resulting depression
THE PRESENCE OF WHAT MAKES BONE ARISING FROM ENDOCHONDRAL ADN INTRAMEMBRANOUS OSSIFICATION INDISTINGUISHABLE
- PRESENCE OF : -OSTEOCYTES
- OSTEONS
- HAVERSIAN CANNALS
- VOLKMANN’S CANNALS
WHAT ARE THE TWO TYPES OF BONES WE SEE IN A BONE
EG. A DRIED FEMUR
- Cancellous ( spongy / trabecular bone)- forms network of fine bonds columns which combine STRENGTH AND LIGHTNESS
- Spaces filled with bone marrow
- Compact bone (cortical) - forms EXTERNAL surfaces of bone
- Contributes to 80% of skeletal mass
WHICH BONE CONTRIBUTES MOST TO THE BODY’S SKELETAL MASS?
- COMPACT (CORTICAL) BONE -80% OF BODY’s skeletal mass
WHAT DO HAVERSIAN AND VOLKMANNS CANALS CARRY?
- Blood vessels
- Lymphatics
- Nerves
WHAT IS THE DIFFERENCE BETWEEN VOLKMANN’S AND HAVERSIAN CANNALS?
- Haversian CANNALS- tend to run longitudinally
- SURROUNDED BY CONCENTRIC LAMELLAE ( making an osteon)
-VOLKMANN’S CANNALS - tend to round horizontally between H.cannals. DO NOT HAVE CONCENTRIC LAMELLAE around them!
Describe the difference between immature and mature bone
- Immature bone- OSTEOCYTES arranged randomly
- Mature bone - OSTEOCYTES arranged in the concentric lamellae of osteons
- Resorption cannals in mature bone run parallel with the osteon’s long axes (cutting zone)
Describe the osteocytes in lacunae between lamellae ( in cortical bone)
- Osteocytes slender cytoplasmic projections which interact with adjacent osteocytes via caniculi
- Process connect with adjacent osteocytes via GAP junctions allow the transfer of nutrients
- Caniculi connect with central Haversian system
DIFFERENCE BETWEEN CORTICAL AND SPONGY BONE
- Haversian system with the concentric lamellae- osteon- cortical bone
- Spongy bone have trabeculae which have no haversian or volkmanns canal although there are osteocytes between lamellae
- have bone marrow all around the trabeculae
Spongy bone structure
- Trabecule similar to compact bone with osteocytes between lamellae
But no haversian and volkmann canals
Each trabeculae has numerous osteocytes embedded in irregular lamellae of bone ( dispose tissue and haemopoeitic cells in the cavity)
-Osteoblasts and Osteoclasts on their surface act to remodel it
What is a cutting cone?
- Is boring a tunnel brought the bone via action of osteoclasts
- Osteoclasts release H+ and lysosomal enzymes
- Minute its cut and bone is removed by Osteoclasts, osteoblasts lay down osteoid
WHAT IS OSTEOID?-
- ORGANIC CONTENT OF BONE
- UNMINERALISED
- 90% COLLAGEN
- 10% GROUND SUBSTANCE
WITH THE BONE REMODELING WHAT DO WE SEE IN TERMS OF HAVERSIAN SYSTEMS?
You have first, second, third generation Haversian system
- Can see remnants of old Haversian systems
- (have movement of osteons)
What is the ability of osteons?
- Ability to branch and terminate
WHAT IS THE STRUCTURE OF CORTICAL (compact) BONE?
- compact bone is organised into parallel columns- Haversian systems
- H.s - composed of concentric lamellae (parallel H.C and perpendicular V.C)
- Lamellae of H.S created by osteoblasts which secrete matrix and trapped in a lacunae- osteocytes
What are the Layers of Long bone from exterior - in?
- PERIOSTEUM - surface of cortical bone
- Outer circumferential lamellae
- Compact bone- Haversian system
- Inner circumferential lamellae
- ENDOSTEUM ( Endosteal surface of trebacullar bone)
WHAT IS THE COMPOSITION OF BONE?
- 65% Mineral ( calcium hydroxyapatite crystals)- contributes to hardness of bone
- 23%- TYPE 1 COLLAGEN
- 10% Water
- 2% non-collagen proteins