musculoskeletal system Flashcards
what are the 3 different types of cells in the bones e
- oestoblasts - bone makers
- oesteoclasts - bone breakers
- oesteocytes - bone maintainers
what is the structure of bone s
formation of bone
1. oesteoblasts lay down oestoids
2. calcification
3. oesteoblasts become immobolised
4. oesteocytes maintain surrounding oesteoids
bone reabsorption
1. oesteoclats secrete acids and enzymes
2. acid disloves calcium phosphate crystals
3. enzymes degrade osteoids
4. calcium and phosphate released into the blood
how does long bone growth occur
- the chrondrocytes produce new cartilage in epiphyseal plates ( these plates are located at each end of the bone between the shafts of the bone and the secondary ossification centre)
- this plate widens causing the bone to lengthen
- the chrondrocytes will die
- oesteocytes replace the chrondrocytes and then lay down bone
- the epiphyseal plates then close once puberty hits
this process is affected by sex hormones
what are some of the effects of growth hormones gh
-dwarfism
- decreased gh in children
- gigantism
- increased gh pre puberty
- acromegaly
- increased gh in adults - affects their facial feature s
what are othe hormones nd their affects on growth
thyroid hormones
- needed for the synthesis of gh
insulin
- allows gh actions to occur
sex hormones
- important for puberty
glucocorticoids
- inhibits growth
- children with inhalers may be deficient in this
what are some bone and joint diseases
bone
- osteomalacia- rickets
- osteoporosis
joint
- oesteoathrisis
- gout
- rheumatoid arthritis
what is oesteomlaacia, treatments, and causes
- deficiency in bone mineralisation
causes
- lack vitamin d2
-lack vitamine d3 (sunlight)
- renal disease can cause
traetements
- ergocalciferol - type of vitamin d in food
- calcitriol
what is osteoporosis
this si when someone has a low bone density, thi sis mos common in elderly women who are post menopause
- usually occur in fractures of te hip area
someone is more likely to suffer from a fracture if
- they have pious history of fracture s
- frequent use of glucocorticoids
- history of falls
- family history
- low bmi
- smoking
what is oestoathritis and rheumatoid arthritis
rheumatoid arthritis
- inflammation of the joints
- damage to articulate surface
- untreated. leads to joint deformation
- it is treated with steroid, TNFalpha antagonist
oestoarthritis
- hard bony swelling of joints
- mechanical stress wears down the cartilage
- treat pain with NSAIDs
what is gout
- the deposit of urine acid crystals in joints
- this triggers acute arthritic symptoms due to inflammatory response
- ofte the big toe
what is the structure of a joint
- capsule
- synovial fluid
- articulate cartilage
- liagaments
what is the structure of skeletal muscle fibres
each muscle fibre is organised into myofibrils - this is composed of two proteins thin and thick filaments
thick filaments
- tails facing the m line
- head facing the thin filaments
- the myosin head has two binding sites ; the actin being site and ATPase
- the heads interact with the thin filaments
thin filaments
- thin filaments are made up of 3 proteins
actin - a globular protein with a binding site for my so sin
troponin - this is a regulatory protein which has a binding site for actin, tropomyosin and calcium which regulates muscle contraction
tropomyosin - interacts with actin, myosin, and troponin to regulate muscle contraction.this structure spirals around actin to give it stability
what is the role of calcium
when there is no calcium present
- troponin hols tropomyosin over myosin binding sites on actin
- so there is no cross bridges and the muscles are relaxed
when there is calcium present
- calcium binds to troponin
- movement of troponin
- movement of tropomyosin
- formation of cross bridge
- contraction state
- this requires atp
what is excitation - contraction and what rea teh stepson of it
this is how muscle contractions are turned on and off
- a neurotransmitter is released
- this send an action potential to the sacrlemma in the cell membrane
- this action potential then transverse down the tubules
- the DHP receptors on the tubules then opens the calcium channels
- increasing the levels of calcium.
- allowing more calcium to bind to troponin which will shift tropomyosin
- then the cross bridge cycling occurs
how does contraction stop
- calcium leave st he troponin allowing tropomyosin to cover myosin binding sites on actin
- the way calcium leaves is through ATPase in the sacroplasmic reticulum transports calcium from cytosol into the sacroplasmic reticulum
- so this is the end of the action potential
how do muscle cells provide atp to drive the cross bridge cycle
there are two ways this can be done
- the atp is used by muscles
- cross bridge cycle
- splitting of ATP by myosin ATPase (power stroke)
- binding of fresh ATP to myosin to cause dissociation - ATP used to maintain ion gradient
- active transport of calcium into sacroplasmic reticulum
- relaxation
- na/k pump
- maintain ion gradients and membrane potential
