MUSCLES/MOVEMENT Flashcards
what is a motor unit?
motor neuron and the skeletal muscle fibers innervated by that motor neuron’s axonal terminals
what is a motor end plate?
another word for NMJ- the communication between a lower motor neurone synaptic terminal and an individual skeletal muscle cell
which neurotransmitter is used at the NMJ of muscles in mammals?
acetylcholine
synaptobrevin and synaptotagmin are which type of SNARE protein?
V SNARES
vesicle
syntaxin and SNAP-25 are which type of SNARE protein?
T SNARES
transport
what are active zones?
specialised regions of neuronal membrane where vesicle release occurs
main components are Cac and Brp
why is the active zone functionally important?
organisation in this way means only microdepolarisation of Ca2+ needs to occur before vesicles are released
what is the function of troponin I?
binds myosin binding site
what is the function of troponin C?
Ca2+ binding
what is the function of troponin T?
binds tropomyosin
which molecule leaves the myosin head in the power stroke?
ADP
in the recovery stroke, what reaction occurs so that myosin is ready to bind actin again?
ATP hydrolysis
what causes myosin detachment from actin?
ATP binding
Lack of ATP is rigor mortis
what is the function of transverse t tubule networks?
allows efficient spread of depolarisation and co-ordinated contraction
what is the function of tropomyosin?
covers the actin binding sites on myosin
moved via interactions with troponin T
what is myasthenia gravis?
neuromuscular autoimmune disease whereby antibodies are raised against nicotinic Ach receptors
simple movements require huge effort
what is isotonic contraction?
contraction where muscle shortens to manage load
what is isometric contraction?
contraction where a muscle is at a constant length, but there is an increase in tension
why do muscles contract more efficiently at their optimum length?
myosin and actin make the optimum number of connections at this length
how does the botulinum toxin work?
disrupts SNARE proteins, meaning no Ach release into synapse
how does tetanus work?
cleaves synaptobrevin, causing paralysis
what is the function of titin?
links Z line to M line, stabilising the myosin filament
what is the function of tropomodulin?
binds the negative ends of actin filaments at the m line
what is the function of desmin?
links together myofibrils at the Z disk
what is the function of dystrophin?
links muscle filaments to outer cell membrane, hence making it move!!
what is nebulin?
the structure that determines the length of the actin filament
how is muscle fibre type determined?
determined by gene expression, but neuronal firing controls gene expression in early development
therefore, neuronal firing controls gene expression
how many ATP are made per round of oxidative phosphprylation?
38ATP
where does glycolysis occur?
Cytsol
how amny ATP are produced by glycolysis?
2ATP
what is the substrate for glycolysis?
Glycogen
DOESN’T REQUIRE OXYGEN
what is the creatine phosphate system?
creatine phosphate + ADP = creatine + ATP
10 seconds
catalysed by creatine phosphatase
used as a last resort energy source
what is the cori cycle?
use of oxygen to produce glucose from lactate in the liver
what is the myokinase energy system?
ADP+ADP= ATP + AMP
what is the percentage conversion of dietary calories and metabolic fuel production?
20%
what is the fuel guage of the cell that indicates when metabolic substrates are at their lowest?
AMP
signals via AMPK pathway
NFKB and myostatin are involved in which muscle process?
muscle atrophy
what is the flow rate of skeletal muscle?
1-4ml/100ml
what is functional sympatholysis?
a local vasodilatory mechanism whereby sympathetic vasoconstriction is overriden during exercise
how are fine motor skills controlled?
by only a few muscle fibres per motor unit
how are gross motor skills i.e. posture, controlled?
many muscle fibres per motor unit
1 muscle is controlled by, on average, how many motor neurones?
100
how many individual muscle fibres does one motor neurone control?
100-1000
what is aerobic endurance?
ability of the body to sustain a high work rate, technical quality throughout training, without fatigue
what is muscular endurance?
ability to perform repeated contractions without fatigue
what is muscle hypertrophy?
response to training in which individual myofibrils grow in size
what are the WHO bandings of physical activity?
sedentary
mild
moderate
vigorous
what are the NHS physical activity guidelines?
150 minutes of moderate intensity exercise
75 minutes of vigorous intensity exercise
muscle strengthening 2 days a week
elderly patients - balance co-ordination twice a week
how is physical activity prescribed?
Dose = intensity x duration
what is chondromalacia?
condition whereby cartilage on posterior surface of patellar softens, causing chronic inflammation between patella and trochlear groove
what is patella tracking disorder?
when the patella shifts out of the trochlear groove, caused by muscular imbalances between quads and hamstrings
what are sharpeys fibres?
connective tissue collagen fibres that connect periosteum to bone
pulled away from bone in shin splints
what is the lachmanns test?
flexion of knee - anterior translocation - no endpoint hit? = ACL instability
what is the pivot shift test?
test indicating ACL pathology
similar to lachmans
what are osteophytes?
bony projections along joint margins caused by ageing, degeneration or disease
what is the relationship between symptoms and placebo treatment?
NOT CAUSAL
