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ACEM part 1 physiology > Nerves and muscles > Flashcards

Nerves and muscles Flashcards

1
Q
  1. With regard to the action potential in a neuron with an RMP of -70mV
    a. The firing level is likely to be -30mV
    b. The overshoot will not extend much past 0mV
    c. The absolute refractory period occupies only 10% repolarisation
    d. Cl- influx will restore the membrane potential
    e. Increase of the external (chloride) increases the resting membrane potential
A

D

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2
Q
  1. In skeletal muscle
    a. Tropomyosin is made up of 3 subunits
    b. The heads of actin contain ATP hydrolysis sites
    c. The myosin is contained entirely within the A band
    d. Troponin T inhibits the interaction with myosin
    e. The immediate energy source for contracting is GTP
A

C

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3
Q
  1. In the action potential of cardiac muscle fibre
    a. The resting membrane is -50mV
    b. Phase I is due in part to the rapid chloride influx
    c. Sodium channels are progressively inactivated during phase 1
    d. The repolarisation time increases as the heart rate increases
    e. Is usually 20ms duration
A

C

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4
Q
  1. The special feature of the contraction of smooth muscle is
    a. Actin is not involved
    b. Myosin is not involved
    c. Calcium is not involved
    d. ATP is not the energy source
    e. The membrane potential is unstable
A

E

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5
Q
  1. Inhibitory neurotransmitters increase the post synaptic conductance due to
    a. Na
    b. Cl
    c. Mg
    d. Na and Mg
    e. All of the above
A

B

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6
Q
  1. All of the following are neurotransmitters except
    a. Serotonin
    b. Glutamate
    c. Adenosine
    d. Insulin
    Glucagons
A

D

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7
Q
  1. True acetylcholinesterase
    a. Forms acetylcholine from acetate
    b. Is produced in the liver
    c. Functions only at nerve endings
    d. Is involved in GABA metabolism
    e. None of the above1.
A

C

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8
Q

In the formation of adrenaline

a. COMT produces adrenaline from noradrenaline
b. Phenylalanine is converted to tyrosine
c. DOPA is formed by DOPA decarboxylase
d. DA is 2 NA molecules side by side
e. Serotonin formation is a vital intermediate step

A

B

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9
Q
  1. MAO breaks down
    a. Serotonin
    b. Tryptophan
    c. GABA
    d. Glutamate
    e. Glycine
A

A

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10
Q
  1. Sensation for cold
    a. Is relayed via the thalamus
    b. Is transmitted by the dorsal columns
    c. Is an uncrossed sensory modality
    d. Is mediated by substance P fluxes
    e. Is mediated by A α fibres
A

A

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11
Q
  1. α1 stimulation with lead to
    a. contraction of bladder trigone and sphincter
    b. bronchial smooth muscle relaxation
    c. papillary constriction
    d. increased AV conduction
    e. skeletal muscle vasodilation
A

A

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12
Q
  1. cardiac muscle usually contracts more forcefully when
    a. cell membrane Na/K ATPase activity is stimulated (eg digoxin)
    b. ligand gated Ca channels are open for longer periods
    c. it is titanic (individual responses fused before relaxation can occur)
    d. the average sarcomeres length increases
    e. adrenaline activates β1 receptors
A

E

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13
Q
  1. Rhythmicity
    a. Is a consequence of the plateau (phase 2; Ca influx) of depolarization at the SA node
    b. Is a major feature where myocardial muscle differs from skeletal and smooth muscle
    c. At the SA node is a consequence of the prepotential
    d. At the AV node is a consequence of Na leak into the cell during diastole
    e. Is accelerated in the AV node by neuro-hormonal effects on K channels
A

C

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14
Q
  1. With respect to nerve fibre types
    a. The speed of conduction is inversely proportional to the diameter of the fibre
    b. C fibres are more susceptible to the effects of local anaesthetics than A fibres
    c. A γ fibres are concerned primarily with somatic motor function
    d. Pain may be relayed by all fibre types
    e. A α fibres are efferent only
A

B

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15
Q
  1. inhibitory post synaptic potentials involve
    a. localized increase in membrane permeability to Na
    b. localized decrease in membrane permeability to Cl
    c. localized increase in membrane permeability to PO4
    d. localized increase in membrane permeability to Cl
    e. localized decrease in membrane permeability to K
A

D

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16
Q
  1. Which is false
    a. Ca ions bind troponin T
    b. Troponin-I/tropomyosin complexes constitute relaxing protein
    c. Each attachment/detachment cycle shortens muscle length by approximately 1%
    d. ATP is an immediate source of energy
    e. The head of myosin II possesses an actin binding site
A

A

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17
Q
  1. Which of the following nerve types are most sensitive to hypoxia
    a. A α
    b. A β
    c. A delta
    d. B
    e. C
A

D

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18
Q
  1. Which is false regarding smooth muscle contractility
    a. Increased by ACh
    b. Decreased by activation of phospholipase C
    c. Increased by cold
    d. Decreased by cAMP
    e. Increased by stretch
A

B

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19
Q
  1. A sarcomere
    a. Contains 2 separate halves of an A and I band
    b. Is the space between 2 A bands
    c. Is the space between 2 Z lines
    d. Has the T system at the sarcomeres junctions
    e. Contracts when troponin bind to myosin
A

C

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20
Q
  1. Which nerve fibre type is most sensitive to pressure
    a. Aβ
    b. Aγ
    c. A delta
    d. B
    e. C
A

A

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21
Q
  1. Which of the following are not energy sources of muscle
    a. Phosphoryl creatine
    b. Fatty acids
    c. Glucose
    d. Glycogen
    e. Creatine
A

E

22
Q
  1. Regarding neurotransmitters, which is false
    a. Glutamate is excitatory
    b. GABA is inhibitory at presynaptic sites
    c. Glycine is excitatory at postsynaptic neurons
    d. Gamma hydroxybuterate is inhibitory
    e. Aspartate is excitatory
A

C

23
Q
  1. hich of the following nerve fibre types has the fastest conduction
    a. B
    b. A sigma
    c. Aβ
    d. Aγ
    e. C
A

C

24
Q
  1. A decrease in extracellular K
    a. Makes the resting membrane potential more negative in the nerve cell
    b. Has a similar effect in nerve cells as a decrease in extracellular Na
    c. Has little effect on nerve cell membrane potentials
    d. May decrease nerve cell action potential amplitude
    e. Has a similar effect in nerve cells as an increase in extracellular Ca
A

E

25
Q
  1. Muscle spindles
    a. Lie in parallel with extrafusal muscle fibres
    b. Are the only effector organs in the monosynaptic stretch reflex
    c. Do not have a motor supply of their own
    d. Consist of up to 100 muscle fibres
    e. Can be divided into 5 types in mammalian muscle
A

A

26
Q
  1. Large density vesicles in the synaptic knob contain
    a. ACh
    b. Glycine
    c. GABA
    d. Glutamate
    e. Neuropeptides
A

E

27
Q
  1. Nerve fibres
    a. Have decreased conduction speeds with increasing diameters
    b. Type Aα are the smallest
    c. Type Aα conduct modalities of pain and temperature
    d. Have an increased refractory period with increasing diameter
    e. type C are unmyelinated
A

E

28
Q
  1. Regarding the resting membrane potential
    a. The inside of the cell is positive relative to the outside
    b. The Na/K ATPase is electrogenic because it moves 2 Na and 3K across the membrane
    c. The membrane is more permeable to K than to Na
    d. In nerve cells is about -120mV
    e. K moves out of the cell down its electrical gradient
A

C

29
Q
  1. Skeletal muscle
    a. Function as a syncytium and contracts rhythmically in the presence of a pacemaker
    b. Contractile proteins include myosin II and tropomyosin
    c. Has a light I band, divided by a dark A band
    d. Has 3 troponin units, I, T and M
    e. Myosin II is make up of 4 heavy chains and 2 light chains
A

B?

30
Q
  1. Regarding the neuromuscular junction
    a. The myelin sheath thickens at the terminal portion of the axon
    b. ACh vesicles are evenly distributed thoughout the endplate
    c. The impulse alters permeability to Ca and Na
    d. Myasthenia Gravis is a result of antibodies affecting Ca channels
    e. Each impulse releases about 60 ACh vesicles
A

E

31
Q
  1. A β nerve fibres
    a. Conduct touch and pressure impulses
    b. Are unmyelinated
    c. Have the largest diameter of all nerves
    d. Have a slow conduction velocity
    e. Conduct preganglionic impulses
A

A

32
Q
  1. when skeletal muscle contracts
    a. calcium is released and this initiates contraction by binding troponin T
    b. there is always a decrease in the length of the muscle
    c. it does so at a mechanical efficiency of 80%
    d. if it is an isotonic contraction, work is done
    e. the initiating event is ACh binding to a G protein linked receptor
A

D

33
Q
  1. Smooth muscle contractions
    a. Are dependent on an intact nerve supply
    b. Are a result of Ca influx into the sarcoplasmic reticulum
    c. Are smooth, discrete and fine in multi-unit smooth muscle
    d. Are dependent on troponin
    e. Are exaggerated in vitro when bathed in ACh
A

C

34
Q
  1. Regarding synaptic transmission
    a. Opening of Na channels excites the postsynaptic neuron
    b. Voltage gated Na channels on the presynaptic neuron determine the quantity of neurotransmitter released
    c. Neuropeptides are responsible for acute responses of the nervous system
    d. Small molecule type transmitters do not stimulate the receptor activated enzymes
    e. Cholinesterase is responsible for synthesis of Ach
A

A

35
Q
  1. With respect to action potentials generated in nerves
    a. Conduction from synaptic junctions to the termination of the axon is called salutatory conduction
    b. Relative refractory period is defined as the period from the end of the absolute refractory period to the start of after-hyperpolarisation
    c. Decrease in the external environment of Na decreases the size of the action potential
    d. Decrease in the external Ca level decreases the duration of the action potential
    e. Opening the ligand gated Na channels is responsible for the commencement of the spike potential
A

C

36
Q
  1. With respect to troponin
    a. Troponin C inhibits the interaction of actin and myosin
    b. Troponin T contains the binding sites for calcium
    c. Troponin I binds troponin components to tropomyosin
    d. Head of troponin I catalyses ATP to allow myosin to move on actin molecules
    e. None of the above
A

E

37
Q
  1. The Ca/Na channel
    a. In the resting, fully polarized state the m gate is open and the h gate is open
    b. In the resting, fully polarized state the m gate is open and the h gate is closed
    c. In the activated state the m gate is open and the h gate is closed
    d. In the inactivated state the m gate is open and the h gate is closed
    e. In the inactivated state the m gate is closed and the h gate is open
A

D

38
Q
  1. With respect to synapse
    a. Inhibitory postsynaptic potentials are due to localized increase in membrane permeability to Na
    b. GABA is one of the neurotransmitters involved in presynaptic inhibition in the CNS
    c. Metabolism of catecholamines at the synaptic cleft is the major method of terminating their action
    d. Adrenaline is the major neurotransmitter at postganglionic sympathetic endings
    e. Habituation is due to a gradual inactivation of Na channels on repeat stimulation
A

B

39
Q
  1. excitatory amino acids in the brain are
    a. glutamate and GABA
    b. GABA and glycine
    c. Glutamate and glycine
    d. Glycine and aspartate
    e. Glutamate and glycine
A

E

40
Q
  1. The opioid delta receptor is involved in
    a. Analgesia
    b. Respiratory depression
    c. Miosis
    d. Dependence
    e. All of the above
A

A

41
Q
  1. In visceral smooth muscle
    a. Ca for contraction is released from sarcoplasmic reticulum
    b. Membrane potential has a resting value of -90mV
    c. The excitation contraction coupling time is rapid ,10ms
    d. Muscle contracts when stretched in the absence of innervation
    e. Binding of ACh to nicotinic receptors increases calcium influx
A

D

42
Q
  1. In skeletal muscle relaxation
    a. There is a spread of depolarization along T tubules
    b. Calcium is released from troponin
    c. There is increased Na/K conduction in the end plate membranes
    d. A resting membrane potential of -65mV is finally reached
    e. Mg has a crucial role
A

B

43
Q
  1. Regarding synapses
    a. The synaptic cleft is 30-50mm wide
    b. Transmitters are released from synaptic knobs secondary to Na trigger
    c. Amount of transmitter released is proportional to Ca efflux
    d. ACh is present in granulated vesicles in synaptic knob
    e. The EPSP is caused by Na influx
A

E

44
Q
  1. The action potential of a neuron
    a. Is initiated by efflux of Na
    b. Is terminated by efflux of Na
    c. Declines in amplitude as it moves along the axon
    d. Results in transient reversal of the concentration gradient of Na across the cell
    e. Is not associated with any net movement of Na or K across the cell membrane
A

B

45
Q
  1. The functions of tropomyosin in skeletal muscle include
    a. Releasing Ca after an action potential
    b. Sliding on actin during contraction
    c. Binding to myosin during contraction
    d. Acting as a relaxing protein at rest by covering up the sites where myosin binds to
    e. Generating ATP which passes to the contractile mechanism
A

D

46
Q
  1. with regard to contraction and relaxation of skeletal muscle, which is false
    a. contraction involves the release of K from the terminal cisterns
    b. relaxation involves the release of Ca from troponin
    c. prior to contraction, increased Na and K conduction occurs in the end plate
    d. relaxation involves the cessation of the interaction between actin and myosin
    e. contraction involves inward spread of depolarization along T tubule
A

B

47
Q
  1. Regarding nerve fibres
    a. Type C myelinated fibres in the dorsal root conduct impulses concerning pain and temperature
    b. Type A α unmyelinated fibres conduct impulses concerning proprioception
    c. Type A β unmyelinated fibres conduct impulses concerning light touch
    d. Type A γ unmyelinated fibres conduct impulses to the muscle spindles
    e. Type B myelinated fibres are located in the preganglionic autonomic region
A

E

48
Q
  1. In contracting skeletal muscle
    a. The H zone increases
    b. The I zone decreases
    c. The A zone decreases
    d. The A and I zone increase
    e. None of the above
A

B

49
Q
  1. calmodulin is involved in
    a. smooth muscle contraction
    b. smooth muscle relaxation
    c. myocardial contractility
    d. acts to curtail contraction
    e. acts to limit relaxation
A

A

50
Q
  1. Which is false
    a. Muscle utilizes fat in strenuous exercise
    b. Initially get a rise in BSL secondary to increased gluconeogenesis
    c. Insulin secretion decreases
    d. Initially muscle utilizes glucose stores
A

B

ACEM part 1 physiology (3 decks)

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