Physiology

Excitable Tissue

22 May 2012

1. Regarding glial cells, which is false?a. continue to undergo cell division into adulthoodb. microglia arise from macrophagesc. astrocytes are responsible for the blood brain barrierd. protoplasmic astrocytes are found in white matter

2. Which of the following is an example of a multipolar neuron?a. invertebrate neuronb. Pyramidal cell of the hippocampusc. Ganglion cell of dorsal rootd. Retinal neuron

3. Regarding Axoplasmic flow, which of the following is true?a. wallerian degeneration occurs when a nerve is crushedb. dynein and kinesin are required for protein transportc. retrograde transport occurs along microtubules at 0.5-10mm/dayd. orthograde transport moves from the axon terminal to the cell body

4. Which of the following is false regarding the Resting membrane potential of neurons?

a. is usually – 70 mVb. is close to the equilibrium potential for Na+c. requires a concentration gradient to be presentd. requires membrane permeability to a single ion species

5. With regard to Action Potentials, which of the following is incorrectly paired?a. Threshold potential – voltage gated Na+ channelsb. Repolarization – voltage gated K+ channelsc. After-hyperpolarization – voltage gated K+ channelsd. After-hyperpolarization – ligand gated K + channels

6. The spatial distribution of ion channels along an axon plays a key role in the initiation and regulation of action potentials. Which of the following has the least number of voltage gated Na+ channels?

a. Nodes of Ranvierb. cell bodyc. axon terminalsd. myelin

7. Which of the following Nerve Fibre Type has the slowest conduction velocity (m/s)?

a. Aαb. Aβc. Bd. C

8. Which of the following neurotrophins can bind to more than one trk Receptor?a. Nerve Growth Factorb. Brain-derived neurotrophic factorc. Neurotrophin 3d. Neurotrophin 4

9. Which of the following Nerve Fibre types is least susceptible to hypoxia?a. Aαb. Bc. Aβd. C

10. Regarding neurotrophins, which is not true?a. Ciliary neurotrophic factor = promotes the survival of damaged and

embryonic spinal cord neuronsb. Glial cell line-derived neurotrophic factor = maintains medullary

dopaminergic neurons in vitroc. Nerve Growth factor = necessary for the growth and maintenance of

sympathetic neuronsd. Leukemia inhibitory factor = enhances growth of neurons

11. The contractile mechanism in skeletal muscle largely depends all of the following proteins except:

a. myosin-IIb. myosin-Ic. actind. tropomyosin

12. Regarding skeletal muscle, which of the following equilibrium potentials (mV) is incorrectly paired with its ion?

a.H+ +32b. K+ -95c. Cl- -90d. HCO3 -32

13. Which of the following is not a property of Type IIA skeletal muscle fibre types?a. red colourb. large diameterc. resistant to fatigued. moderate glycolytic capacity

14. Regarding heat production in muscles, which of the following is incorrect?a. relaxation heat = external manifestation of basal metabolic processesb. activation heat = produced from muscle contractionc. shorting heat = produced from structural change in muscle while shorteningd. recovery heat = released during restoration of muscle to pre-contraction state

15. Which of the following cell components are found in cardiac muscle fibres but not skeletal muscle fibres?

a. sarcolemmab. sarcoplasmic reticulumc. Terminal cisternd. intercalated discs

16. Which of the following neurotransmitter is correctly colocalized with a neuropeptide?

a. Acetylcholine – cholecystokininb. Serotonin – neurotensinc. glutamate – substance Pd. glycine – cholecystokinin

17. Which of the following neurotransmitter does not use cyclic AMP as a second messenger?

a. Glutamateb. Serotoninc. Dopamined. Norepinephrine

18. Select the incorrect statement regarding the microscopic appearance of striated muscle fibres:

a. the area between two adjacent M-lines is called a sarcomereb. the thin filaments are made up of actin, tropomyosin and troponinc. the thick filaments are made up of myosind. if a transverse section through the A-band is examined under the electron microscope, each thick filament is seen to be surrounded by 6 thin filaments in a regular hexagonal pattern

19. Regarding dopamine, which of the following is false?a. metabolised into active compounds by MAO and COMTb. dopaminergic neurons are located in the nigrostriatal systemc. active reuptake occurs via Cl- dependent dopamine transporterd. overstimulation of D2 receptors is thought to be causal in schizophrenia

20. During muscle contraction, which of the following is not true?a. Ca2+ effluxb. M lines move closer together c. The sliding during muscle contraction occurs when the myosin heads bind firmly to actin and bend at the junction of the head with the neck and then detachd. an action potential causes the release of Ca2+ and this initiates contraction

21. Which of the following is true regarding muscle contraction and relaxation?a. ATP provides the energy for contraction whereas relaxation is passiveb. ATP provides the energy for relaxation whereas contraction is passivec. ATP provides the energy for both contraction and relaxationd. ATP provides the energy for contraction, relaxation involves GTP

22. Regarding smooth muscle, which is false?a. smooth muscle cells are largely under the control of the autonomic nervous systemb. unitary smooth muscle contraction is synchronised by gap junction communicationc. multiunit smooth muscle contraction can occur voluntarily via coordinated motor unitsd. Ca2+ regulation of contraction is primarily through phosphyorylation-

dephosphylation reactions

23. Which is false with respect to Serotonin:a. is present in highest concentration in blood plateletsb. the principal urinary metabolite is 5-HIAA (5-hydroxyindoleacetic acid)c. can be found in the midline raphe nuclei of the brain stemd. is activated by monoamine oxidase

24. Which of the following is not a physiologic effect produced by the stimulation of the μ opiate receptor?

a. diuresisb. analgesiac. constipationd. miosis

25. Regarding sense organs, which is true?a. Meissner corpuscle responds to changes in textureb. Merkel cells respond to intermittent pressurec. Pacinian corpuscles respond to slow vibrationd. Golgi tendon organ responds to thermal changes

26. Regarding the structure of the muscle spindles, which of the following is false?a. intrafusal fibres run in parallel to extrafusal fibresb. there are two nuclear bag fibres per muscle spindlec. have a motor nerve supply of their ownd. nuclear bag fibre1 has a low level of myosin ATPase activity

27. Which is not true with respect to the Withdrawal reflex?a. it is a polysynaptic reflexb. it occurs in response to painful stimulic. the crossed extensor response is extension of the ipsilateral limb in response to the painful stimulus

d. they are prepotent

28. Choose the incorrect statement regarding the Golgi tendon organ.a. is the receptor for the inverse stretch reflexb. there are 3-25 muscle fibres per tendon organc. involved in regulation of the velocity of the muscle contractiond. stimulation leads to production of EPSPs (excitatory postsynaptic

potentials)

29. When skeletal muscle contracts, which of the following is true?a. calcium is released and this initiates contraction by binding Troponin Tb. there is always a decrease in the length of the musclec. if it is an isotonic contraction, work is doned. the initiating event is acetylcholine binding to a G-protein linked receptor

30. Regarding the resting membrane potential, which is true?a. is +70mV in mammalian cardiac cellsb. is increased with increased external Na+ concentrationc. implies that the inside of the cell is positive relative to the outside of the cell at restd. is decreased by increasing the external K+ concentration

31. Regarding the all-or-none law, which is incorrect?a. slowly rising currents fail to fire the nerve because of adaptationb. threshold intensity is required to be reached for production of an action potentialc. stimulus size will lead to variable action potential amplitude and formd. threshold intensity varies with duration of stimulus

32. Regarding muscular dystrophies, which is correct?a. Becker muscular dystrophy is an absence of dystrophinb. Duchenne muscular dystrophy is an absence of dystrophinc. Dystrophin is present but altered in Duchenne muscular dystrophyd. Malignant hyperthermia is dur to a protein deficiency

33. Regarding synaptic structure and function, which is false?a. the synaptic delay is at least 0.5 msecb. Calcium is essential for neurotransmitter releasec. the synaptic cleft is 20 – 40 nm wided. there are four kinds of synaptic vesicles

34. Regarding EPSPs and IPSPs, which is incorrect?a. IPSP is due to increased chloride transportb. EPSP is facilitated by sodium and calcium channel openingc. IPSP can be due to potassium channel openingd. IPSP can be produced by sodium and calcium channel opening

35. Regarding production of neurotransmitters, which is false?a. GABA is produced by decarboxylation of glutamic acidb. all catecholamines are synthesized from tyrosinec. Epinephrine can only be produced in the adrenal medullad. Tryptophan undergoes hydroxylation in the steps to produce serotonin

36. Regarding nociceptors, which is incorrect?a. Tickle and itch are related to pain sensationb. Bradykinin activates both Aδ and C fibresc. Histamine is more likely to produce itch than kininsd. Allodynia signifies an increased sensitivity of nociceptive afferent fibres

37. With regards to neuropathic pain: a. It is excruciating and difficult to treat.b. It is never accompanied by reflex sympathetic dystrophyc. Parasympathetic discharge brings on pain after overgrowth of nerve

fibres.d. Alpha-adrenergic blockade produces causalgia-type pain.

38. The cortical areas allocated for sensation are smallest at: a. The handb. The mouthc. The trunk and backd. The thumb

39. A lesion at the optic chiasm results in: a. homonymous hemianopiab. heteronymous hemianopiac. homonymous hemianopia with sparing of the fibres from the maculad. blindness in one eye

40. Nystagmus a. is initiated by visual impulses

b. is not present in blind individualsc. can be horizontal, vertical or rotatoryd. is rotatory when the head the head is tipped sideways during rotation

41. With regards to smell and taste which statement is false: a. Information from the olfactory bulb travels via the lateral olfactory

stria directly to the olfactory cortex.b. Taste buds are comprised of basal stem cells and three types of taste

cells.c. Afferents from taste buds travel via CN VII, IX and X.d. Olfactory sensory neurons are located within the lower portion of the

nasal cavity.

42. Regarding cellular elements of the CNS, which of correct?a. Microglia consists of oliodendrocytes, Schwann cells and astrocytesb. Fibrous astrocytes are found predominatly in grey matterc. Protoplasmic astrocytes produce substances that are trophic to neuronsd. The cell body is always at the dendritic end of the axon

43. Regarding excitation and conduction, select the true statement.a. Excitation may be caused by electrical, chemical or mechanical stimulib. Action potentials (nerve impulses) are conducted passivelyc. Potential differences occur when there is equal distribution of ions

across the cell membraned. Only propagated potentials occur in neurons

44. Regarding Ionic flux, which is correct?a. Na concentrations are higher inside the cellb. K channel opening is slower and more prolonged that Na channel

openingc. Na channel opening causes repolarisationd. Decreased extracellular Ca concentrations decrease excitability

45. With respect to nerve fibre and function, which of the following is incorrect?a. The latent period id proportional to the speed of conductionb. Smaller diameter nerve fibres have a greater speed of conductionc. Nerve fibres are divided into A, B, C and D groupsd. Local anaesthetics affect C fibres before they affect A fibres

46. Which is true of the trophic support of neurons?a. Neurotrophins are always transported via retrograde transport to the

cell bodyb. Neurotrophins only act at TRK receptorsc. NGF (Nerve Growth Factor) is necessary for growth and maintenance

of sympathetic neuronsd. Astrocytes are not involved in the production of neurotrophins

47. Regarding the anatomy of the synaptic cleft which statement is false?a) the gap between terminal bouton and post synaptic structure is 20-40nmb) there are small vessels with a dense core that contain catecholaminesc) the vesicles are transported to the nerve ending by fast axoplasmic

transportd) In the spinal cord 98% of the synapses on a neuron are on the dendrites

48. Regarding summation of afferent stimuli:a) Temporal summation occurs when multiple synapses occur at the same b) Spatial summation is more likely to reach threshold when there is a short

length constant. c) Temporal summation relies on EPSPs taking a relatively long time to

decayd) Spatial summation of IPSPs occurs but not temporal summation of IPSPs

doesn’t

49. Which of the following is true regarding Excitatory and Inhibitory Postsynaptic Potentials?

a) Closing of K+ channels causes an Inhibitory Postsynaptic Potentialb) Opening of Cl- channels causes an Inhibitory Postsynaptic Potentialc) Closing of Na+ channels causes an Excitatory Post synaptic Potentiald) Increasing membrane conductance to Ca+ generates an Excitatory

Postsynaptic Potential

50. Regarding nerve endings on smooth muscle cells which statement is incorrect?a) Large vesicles with a dense core containing catecholamines are presentb) Postganglionic neurons branch extensively and innervate multiple smooth

muscle cellsc) Denervation does not lead to atrophyd) Unitary smooth muscle does not require extrinsic innervation to contract

51. Regarding tetanus toxin, which is true? a) Adequate production by bacteria doesn’t lead to death if untreated.

b) Works by blocking the release of Ach at the NMJc) Causes spastic paralysisd) Can be used as an alternative to botulinum toxin in cosmetic procedures in

immunised individuals.

52. Which of the following organs receives both parasympathetic and sympathetic innervation?

a. kidneyb. liverc. gallbladderd. coronary arteries

53. With regards to the enteric nervous system, which of the following is false?a. the myenteric plexus is involved in control of digestive tract motilityb. the enteric nervous system contains about half as many neurons as the

spinal cordc. the submucosal plexus is located between the circular muscle and the

luminal mucosad. the myenteric plexus is located between the longitudinal and circular layers

of muscle

54. Which of the following is not an acetylcholinesterase inhibitor?a. physostigmineb. parathionc. diisopropyl fluorophosphatesd. hexamethonium

55. What is the amount of insensible water loss in the average human in milliliters per hour?

a. 40 ml/hb. 50 ml/hrc. 60 ml/hrd. 70 ml/hr

56. With regards to heat production and body temperature which of the following is correct?

a. the temperature of the scrotum is carefully regulated at 35 degrees Cb. in individuals who sleep at night, the human body temperature is highest in

the late morningc. the oral temperature is normally 1.5 degrees C lower than the rectal

temperatured. normal human core temperature undergoes a regular circadian fluctuation of

0.5 – 0.7 degrees C

57. Which of these is not a touch receptor in the skin?a. Merkel cellb. Pacinian corpusclec. Ruffini endingsd. Schwann cell

58. Which of these is not a sensory receptor classification?a. Nocioreceptorb. Adrenoreceptorc. Mechanoreceptord. Photoreceptor

59. Which of these is untrue about a stretch reflex?a. A stretched muscle will contractb. The sensory organ is the muscle spindlec. Not all reflex arcs involve the CNSd. The synapse neurotransmitter is usually glutamate

60. Regarding the knee jerk reflex, which is true?a. Is a polysynaptic stretch reflexb. Hyperactive reflex signifies an interruption in the spinothalamic tractc. Absence of the reflex signifies an abnormality in the muscle spindlesd. Most common cause of hyperactivity is peripheral neuropathy due to

diabetes or alcohole.

61. What is the correct order of the reflex arc?a. Sensory organ – afferent neuron – synapse – efferent neuron – effector responseb. Sensory organ – synapse – afferent neuron – efferent neuron – effector responsec. Sensory organ – efferent neuron – afferent neuron – synapse – effector response

d. None of these62. Which of the following cells are not found in the central nervous system?

a. Oligodendrocytesb. Schwann cellsc. Microgliad. Astrocytes

63.. Which of the following statements with regard to nerve tissue is false?a. Intracellular and extracellular K concentrations are the prime determinants of the resting membrane potentialb. Increase in extracellular calcium increases the excitability of nerve and muscle cells.c. The direction of the electrical gradient for Na is reversed during overshoot phase of the action potentiald. The process of nerves failing to fire when exposed to slowly rising currents is called adaptation

64. Factors involved in returning the membrane potential to its resting state following an action potential include all of the following except:

a. Closing of voltage-gated Na channelsb. Reversal of the electrical Na gradient during overshootc. Opening of voltage-gated K channelsd. Closing of ion-gated Na channels

65. With regard to nerve fibre types and their functions, which of the following is incorrectly paired?

a. C – Postganglionic sympatheticb. Aδ – Motor to muscle spindlesc. B – Preganglionic autonomicd. Aα – Somatic motor

66. Which of the following nerve fibre types is most susceptible to local anaesthetics?a. Aαb. Bc. Aβd. C

67. The following neurotransmitters are synthesised from tyrosine except:a. Dopamineb. Norepinephrinec. Glutamated. Epinephrine

68. Which of the following is true about receptors?a. All receptors are post-synaptic

b. There is only one receptor type for each ligandc. Prolonged exposure to ligands causes decreased receptor responsed. Ligand-receptor binding can only cause effect through second messengers

69. Which of the following statements about cholinergic transmission is FALSE?a. Action is halted by hydrolysis of Acetylcholine (Ach)b. Atropine blocks Nicotinic receptorsc. ACh is reuptaken into the pre-synaptic knob unchangedd. Muscarinic receptors are mainly found in the peripheral nervous system

70. The following neurotransmitters are inactivated by monoamine oxidase (MAO) except:

a. Acetylcholineb. Epinephrinec. Dopamined. Serotonin

71. Which of the following is not an effect of stimulation of the µ opiate receptor?a. Constipationb. Hyperventilationc. Miosisd. Euphoria

72. The Bell-Magendie law states:a. Spinal cord dorsal roots are motorb. Spinal cord ventral roots are sensoryc. Spinal cord dorsal roots are sensoryd. Stretch reflexes are all monosynaptic

73. Regarding monosynaptic reflexes:a. Intrafusal fibres are at right angles to extrafusal fibresb. The two types of sensory endings in spindles are Ib and IIc. Spindles themselves have no motor supplyd. The neurotransmitter at the central synapse is glutamate

74. Which of the following is NOT a type of pain receptor?a. Stretch nocireceptorb. Mechanical nocireceptorc. Thermal nocireceptord. Polymodal nocireceptor

75. Referred paina. Always refers to a single dermatome

b. Can refer to the opposite side of the bodyc. Is not useful in the clinical settingd. Is best described by the Divergence-Projection theory

76. Regarding the withdrawal reflexa. A flexor response is predicted in the contralateral limbb. Monosynaptic transmission is typicalc. Reverberating circuits are uncommond. Flexion of the ipsilateral limb with extension of the contralateral limb

characterises the crossed extensor response.

77. VMAT 1 & 2 reuptake all of the following except:a. Acetylcholineb. Dopaminec. Norepinephrined. Histamine

78. Activation of which receptor would be expected to decrease anxiety?a. Glutamateb. GABAA

c. 5HT3

d. Nicotinic cholinergic

79. Which reaction is incorrect?a. Choline acetyltransferase catalyses formation of acetylcholineb. Histamine formed by decarboxylation of histadinec. Tyrosine to Dopa by dopa β-hydroxylased. Norepinephrine metabolised by MAO and COMT

80. Which receptor increases cAMP?a. α1

b. α2

c. D1

d. D2

81. Which would not increase noradrenergic transmission?a. A drug that enhances tyrosine hydroxylaseb. A drug that inhibits dopamine β-hydroxylasec. A drug that inhibits monoamine oxidased. A drug that inhibits norepinephrine reuptake

82. Which is true of Duchenne muscular dystrophy? a. Dystrophin protein is absent from muscleb. Is usually fatal by the age of 12c. Is not x-linkedd. Becker muscular dystrophy is a more serious form

83. With regards to classification of muscle fibre types, which is true?a. Type 1 is fast glycolyticb. Type 11A is fast oxidative/glycolyticc. Type 11B is fast oxidatived. Type 1 has large diameter

84. All the following are false with regard to Skeletal muscle except:a. A sarcomere is the area between 2 adjacent M linesb. Myosin is the thin filamentc. Actin is the thin filamentd. Troponin is made up of 2 subunits

85. Which is FALSE with regards to muscle twitch ?a. Is a brief contraction caused by a single action potentialb. Is followed by relaxationc. Starts about 2 ms after the start of membrane depolorisationd. Starts after repolarisation is complete

86. Select the correct statement with regards to the motor unit.a. A single motor unit is the motor neuron and all the fibers it suppliesb. In the hand one motor unit innervates ~600 muscle fibresc. Each motor neuron innervates several types of muscle fibresd. The recruitment of motor units is random.