a) travel along neurons at a set velocity
b) are only seen in neurons
c) are generated initially by action of K+ voltage gated channels
d) result from variation in Na+
and K+
membrane permeability
e) are unidirectional impulses
a) only contraction is energy requiring, not relaxing
b) sequestering of Ca2+ causes separation of actin-myosin bands and muscle
relaxation
c) ATPase clefts are on the tips of the myosin beads
d) ryanodine receptors are voltage gated Ca2+ chains
e) Troponin T inhibits the interaction of actin and myosin
a) T tubules are extensions of extracellular space
b) “cystems’ of SR are in contact with T-tubules
c) myosin molecules combine to form thick filaments while actin,
tropomyosin, and the troponins the t…..
d) an individual muscle cell is a myofibril, containing myofilaments
e) the sarcolemnia transmits action potentials
a) skeletal muscle cells act as syncytram, though intercellular
communications
b) some skeletal muscles are not subject to voluntary control
c) smooth muscle contains regularly discharging pacemaker
d) a variant of smooth muscle is found in the eye, which resembles skeletal
muscle
e) cardiac muscle does not contain regular striation
a) metabolic rate of muscle may increase 100 times in maximal activity
b) muscle cells can be excited chemically, mechanically and electrically, to
produce action potentials in the cell membrane
c) actin is a myosin-binding protein which is a molecular motor, converting
ATP energy to monomers
d) mitochondria are packed in between myofibrils
e) T tubules occur over the junction of I and A bands
a) 70% of energy requirement of nerves is used in maintaining polarity across
the recytlemina by action of Na-K ATPase
b) metabolic rate of nerves doubles in max action
c) “C” type fibres are non-myelinated and include some of the sympathetic
preganglionic fibres
d) “A” and “B” fibres are all myelinated
e) effects of local anaesthetic are maximal in “C” fibres
a) pH is the negative natural logarithm of [H+]
b) pH 5 to pH 6 involves tenfold increase in [H+]
c) pH remains 7.4 +/- 0.05 in ECF, stabilised by buffer
d) H2O and CO2 H2CO3 H+
and HCO3-, adding H+ shifts the
equilibrium to the right, while adding ??? shifts it to the left
e) the Donnan effect does not contribute significantly to the balance of
electrolyte between intra and extra vascular compartment
a) 1/3 total body weight is extra and 2/3 intra cellular
b) 60% of body weight is water
c) plasma is 8% and total blood 10%, of body weight
d) of extracellular fluid, 25% is vascular, 75% extravascular
e) interstitial fluid is 15% of body weight
a) acetylcholine is synthesised by true cholinesterase
b) atropine blocks muscarinic cholinergic receptors
c) catecholamines are formed from VMA (vanillylmandelic acid)
d) adrenaline has a higher affinity for α rather than β adrenergic receptors
e) dopamine is formed by COMT from tryptophan
a) HERG really is the acronym for human ether-a-go-go related gene
b) intercolated discs are calcified structures within cardiac muscle cells
c) resting membrane potential is -90mV
d) cardiac muscle requires continuous supply of O2 to function
e) cardiac muscle action potential time decreases with increasing heart rate
