Muscoskeletal 1: Bone Flashcards
What are the two main skeletal regions, # of bones and the main regional differences in function
Axial skeleton (core) : 80 bones (some paired) Appendicular skeleton (outside) : 126 bones ( all paired) -Regional differences is that axial is mainly for support/protection and has Haemopoeisis and -Appendicular is for movement and fat storage
What are the 6 functions of the skeletal system
- Support (hand soft tissue),
- Protection (hard and dense),
- Movement (framework for pulling),
- Ca+ (for AP& muscle contraction) and Phosphorous (building body) reserves,
- Haemopoeisis (red bone marrow)
- Fat storage (yellow bone marrow)
What is the regional zones of long bone
At the ends are the epiphyses, Then inwards of that there is are transitory region called metaphyses, and then middle is the Diaphysis.
Describe the layers of Epiphysis from out to in
Epiphysis has 3 layers
- Outermost is Articular cartilage: in contact with another bone
- Thin layer of Compact bone
- 5 Blood vessels: (inside compact bone and between trabeculae-> into the medullary cavities)
- Spongy bone- made of trabeculae covered in Endosteum with Medullary cavities in between containing red bone marrow.
Describe the layers of Diaphysis from out to in
- Outermost is the Periosteum (outer fibrocellular sheath surrounding bone).
- 5-3 Blood vessels and nerves in the periosteum to compact bone
- Perforating Sharpey’s fibers: (provide strong anchorage of collagen fibres to transition Periosteum to compact bone- tendons attach here)
- Thick layer of Compact bone
- Endosteum : fibrocellular layer lining the medullary cavity
- Medullary cavity: yellow bone marrow
What are the main differences between the Epiphysis and the Diaphysis
The epiphysis receives uniform perpendicular forces like a roof, so therefore has trabeculae cross structures
The Diaphysis receives parallel compression forces therefore has a thick compact bone section like walls o house
What is a connective tissue
It is Cells + ECM. ECM is made of fibres and grounds substance
Compare the properties that make bone a specialised connective tissue : Fibres vs Ground substance (forces, organicness, dry weight) and Cells
Fibres: Type 1 Collagen=1/3 dry weight. Resists stretching/pulling force ( tension)
GS: Hydroxyapatite (Ca and P store) =2/3 dry weight. Resists crushing, squeezing force (compression)
Overall Bone resists Torsion (twisting force)
Cells: Osteo genic, blast, cyte, clast
Describe the Precursor, location, function of Osteogenic cell/ Osteoprogenitor cell
Precursor: Unspecialised stem cell from Mesenchyme, the embryonic CT
Location: Surface of bone in the periosteum and endosteum. Also found in the central canals of compact bone
Function: Normally dormant/resting but can divide and supply developing bone with bone forming cells
Describe the Precursor, location, function of Osteoblast cell
Precursor: Osteogenic cell
Location: Usually in the layer under the peri or endosteum of active bone-> wherever new bone is being formed
Function: Synthesis and depositation and calcification of the osteoid
What is the osteoid
The organic ECM matrix (mostly collagen) of bone, synthesised by osteoblasts prior to mineral depositation.
- Made of 70% collagen, 30% proteoglycans other proteins and water.
What is calcification and its rate + limitations of rate
Calcification is the deposition of mineral salts, primarily hydroxyapatite in a framework of collagen fibres, making the tissue harden.
The rate is initially very fast but then gets very slow (years) because the calcification means that nutrient movement is slow because of dense + displacement of water.
Describe the Precursor, location, function of Osteocyte cell
Precursor: Osteoblast
Location: Trapped within lacunae inside bone. Osteocytes can communicate with neighbouring cells through their long cellular processes inside caniculi
Function: Bone tissue maintenance through
- live lattice inside bone
- localised minor repair
- Rapid Ca+ exchange
What is the organic vs inorganic part of bone as a CT
Organic : Type 1 collagen (70%) 30% other proteoglycans + other proteins and water (fibres)
Inorganic is the hydroxyapatite =ground substance
