Musculoskeletal Flashcards
What are the purposes of the skeleton?
Protection, mineral storage, aid movement, transmits body weight, houses bone marrow
What are the two parts of the skeleton?
The axial skeleton(scull spinal cord 80 bones), appendicular skeleton 126 bones)
What are the shapes of bones?
Long bones tubula with hollow shaft, short bones cuboidal in shape, Flat bones plages of bone often curved, irregular bones, sesamoid bones oval or round in a tendon
What are the macroscopic types of bone?
Cortical bone compact very dense and only got spaces for cells and blood vessels, Trabecular cancellous spongy bones hollow with spaces
What is the tip of a bone called?
Epiphysis
What is the middle of a long bone called?
Diaphysis
What is the middle of epyphsis and diaphysis?
Metaphysis
What are the types of microscopic bone?
Woven bone, Lamellar bone
What is woven bone?
Made quickly disorganised no clear structure.
What is lamellar bone?
Made slowly organised layered structure often replaces woven bone
What is the purpose of long hollow bones?
keeps mass away from neutral axis minimises deformation
What is the purpose of trabecular bone?
gives structural support while minimising mass
Why are the heads of bones usually wide?
Spreads load over larger area
What is the composition of bone?
Mineral 50-70% hydroxyapetite, 20-40% organic matrix lots of collagen and noncollagenous proteins, 5-10% water
It is fibres of protein then mineral deposited between them.
What is an osteoclast like?
Multinucleated they are on the surface of the bone they are. they are mesenchymal derived cells
What are osteoblasts?
They are plump cuboidal cells on the surfaces of the boen
What are osteocytes like?
they are cells with projections into the bone they are inside the bones
What do osteoblasts do?
Form bone in form of osteoids, produce type 1 collagen then mieralise it by depositing crystals, tey have high alkaline phosphatase activity and make non collagenous proteins they secrete factors that reculate osteoclasts RANK ligand
Where do osteoclasts come from?
Haemopoeitic stem cell lineage
What do osteoclasts do?
Resorb bone dissolve mineralsed matrix break down collagen and have high expression of TRAP and cathepisn K
What is bone modelling?
Gross shape is altered and bone added or taken away
What is bone remodelling?
All of the bone is altered new bone replaces the old bone
Why does bone remodelling take place?
Form bone shape, replaces woven bone with lamellar bone, reoritate fibrils and trabeculae in facourable direction for mechanical strenght, responding to loading, repair damage obtain calcium,
What are the stages of bone healing after a break?
Periosteum tears haematoma, callus forms cartilage then becomes bony then remodelling
How can you treat osteoporosis?
Stop breakdown, and increase formation
How many types of collagen are there?
20
What is the most abundant type of collagen?
Fibrillar
What is the strucute of collagen?
2 types of protein Alpha 1 and, 3 fibres , has a wavy structure dumbell end at N termina, there are binding sites along the thing
What gives collagen its strength?
they interlink fibres that are opposing ends
What do many collagen strands make?
Fibrils
What do firbrils make?
fibres
What is tropocollagen?
It is the fibres that are modified to make the collagen fibre itself
What happens with age in collagen?
The bone gets a bit stiffer due to more collagen crosslinks
Why is copper important to collagen?
The crosslinks copper helps lysyl oxidase to form links OH-lysine
What are characteristics of copper deficiency?
Kinky hair, strange hair, washed out bones
What joins tropocollagen together?
Pyridinolines which need vitamin C
What are symptoms of scurvy?
Bleeding gums, bruising, loose teeth
How is collagen type one joined?
Chopping p1NP and chop amino and carboxy ends before its joined.
What is the disease with lack of collagenase?
More prone to fracture of bone
What does vitamin C do for the body?
Helps hydroxylise the collagen
What is osteogenis imperfecta?
Common in children bone fragility, bad problems in collagen formation, blue sclera, odd teeth, scholiosis, easily fractures in the back
What affects the severity of osteogenesis imperfecta?
Number of fractures per year, and how much bone is dammaged
What can be the problems with osteogenesis imperfecta?
Too much mineral, odd arrangement of collagen fibers
How do osteoclasts do to break down bone?
make a sealed area around bone and release enzymes
What type of growth is bone growth?
Appositional where new tissue is grown from the surface.
What is the type of bone formed in fast situations?
Woven bone
What happens in primary bone growth?
It produces wavy surfaces and this can cause areas to be missed that get filled in later
How are long bones formed?
They grow by endochondral ossification replacement of cartilage with bone
What is the seconday ossification centre in a long bone?
It is an area that is at the end of the long bone that is separate to the shaft where tissue grows
What are the layers of the tissue at the growth plate?
Resting zone, germinal zone, hypertrophic zone, degenerative zone, cartilage resorption and bone formation
What is the technical name for the growth plate in a bone?
Epiphyseal plate
When does bone modelling happen?
During growth, formation and resorption to sculpt adult shape
When does remodeling happen?
In adult 2 million sites, replace and remove old or dammaged bone, to mobilese minerals
What are osteons?
They a feature of growth
What is a primary osteon?
A circular part of the bone that doesnt cross lamellae as it is formed during modelling
When is a secondary osteon formed?
When bone is tunnelled through to make space for vessels
What is a secondary osteon?
It cuts through previous lamellae, formation
What is a Herversian tunnel?
Another name for a secodary osteon
What type of joint is the hip?
Synovial ball and socket
What are the bumps on the femur?
The greater trochanter and lesser trochanter
What is the asitabulum?
The articular surface on the pelvis
What does the iliacus muscle do?
flexion of the hip joint
What is the clinical significance of the abductor muscles of the hip?
It elevates the pelvis on the non weight bearing side of the body
What is the main artery to the leg?
The femoral artery, superficial and profundus
Where does the femoral nerve supply?
Front of the leg
What forms the siatic nerve?
The lumbar plexus
What is important about the siatic nerve in clinic?
You need to avoid it in surgery and intramuscular injection
What are the identifiers of osteoarthiritis on xray?
Less space between the point, osteophytes, subarticular cysts and sclerosis
When is osteoarthritis most painful and where?
Groin pain, night pain
What increases your risk of hip fracture?
Osteoporosis
What is an intracapsular fractrue of the hip?
Happens on the neck of the femur and is serious as breaks blood supply to the head
What is developmental dysplasis of the hip?
found often in first 5 years of life, is developed out of the joint and doesnt grow and doesnt have an ossification centre
What is the use of phosphate in the body?
Phospholipids for bilayer, seccond messengers cAMP, involve in post-translational protein modification, in DNA, in bone minerals
How much phosphate is there?
1% 500-800g it is mainly intracellular and a lot in the bone
How is phosphate in the blood?
50% free ions 35 complexed with Na Ca Mg and 10% bound to proten
What happens with high phosphate?
Hydroxyapitite is formed excessively and deposited in other places such as vessels and soft tissue
What happens with low phosphate?
Low bone mineralisation
What is difference between rickets and osteomalacia?
Kids get rickets
How is phosphate taken in?
In chicken milk soy and nuts mainly in animal dairy and soy
Where is phosphate processed?
In GI absorbed in and out of bone kidney filtres and brings it back some lost in stool and some secreted
How does phosphate enter the body?
It is absorbed through the GI tract by passive diffusion also sodium dependant active transport that is mediated by vitamin D
How is phosphate processed in the kidney?
most goes to filtrate 80% is reabsorbed with sodium cotransporter in PCT, 10% in distal tubule which is passive
How is phosphate levels managed?
Parathyroid hormone, IGF-1, FGF-23
How does parathyroid hormone regulate phosphate?
it increases 1,25 Vit D and this decreases tubular reabsorption of phosphate so increases increases renal exctretion
What does Fibroblast growth factor 23 do?
It increases phosphate excretion through the kidney
What is Autosomal dominant hypophosphataemic rickets?
It is a genetic lack of ability to retain phosphate through the kidneys
What produces FGF-23?
Osteocytes in response to rise in phosphate and high 1,25 Vit D and PTH
Where does FGF-23 active?
It decreases vitamin d activation so reduces absorption in the GI tract and increases excretion in kidney so less in more out
What is Klotho?
Trans membrane protein that is associated with FGF-23 it allows it to act
What is Paget’s disease?
Focal bone disease like osteoporosis
What is coupling in bone?
When bone formation occurs at sites that have previously undergone bone resorption
Where do osteoclasts come from?
Haemopoetic progenitor and myeloid porgenerator
What is arthritis?
Focal erosion periarticular osteoporosis and generalised osteoporosis
What is pleiotropism?
Having many functions in the same and different tissues in conjunction with others
What is redundancy in cytokines?
Many cytokines can do the same role so won’t make a difference if you remove it
What affects osteoclast activity?
PTH 1,25 dihydroxyvitamin D, osetrogen, leptin, IL-1 IL-6 prostaglandins TNF
What controls remodeling?
Osteoblasts
What is osteoprotegrin?
it allows bone to be dense it inhibits differentiation of myeloid precursors into osteoclasts. it binds to rank ligand so rank rankligand interaction is blocked