Download Physiology – Excitable Tissue – 11th May 2010

Physiology
Excitable Tissue
22 May 2012
1. Regarding glial cells, which is false?
a. continue to undergo cell division into adulthood
b. microglia arise from macrophages
c. astrocytes are responsible for the blood brain barrier
d. protoplasmic astrocytes are found in white matter
2. Which of the following is an example of a multipolar neuron?
a. invertebrate neuron
b. Pyramidal cell of the hippocampus
c. Ganglion cell of dorsal root
d. Retinal neuron
3. Regarding Axoplasmic flow, which of the following is true?
a. wallerian degeneration occurs when a nerve is crushed
b. dynein and kinesin are required for protein transport
c. retrograde transport occurs along microtubules at 0.5-10mm/day
d. 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 mV
b. is close to the equilibrium potential for Na+
c. requires a concentration gradient to be present
d. 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+ channels
b. Repolarization – voltage gated K+ channels
c. After-hyperpolarization – voltage gated K+ channels
d. 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 Ranvier
b. cell body
c. axon terminals
d. myelin
7. Which of the following Nerve Fibre Type has the slowest conduction velocity
(m/s)?
a. Aα
b. Aβ
c. B
d. C
8. Which of the following neurotrophins can bind to more than one trk Receptor?
a. Nerve Growth Factor
b. Brain-derived neurotrophic factor
c. Neurotrophin 3
d. Neurotrophin 4
9. Which of the following Nerve Fibre types is least susceptible to hypoxia?
a. Aα
b. B
c. Aβ
d. C
10. Regarding neurotrophins, which is not true?
a. Ciliary neurotrophic factor = promotes the survival of damaged and
embryonic spinal cord neurons
b. Glial cell line-derived neurotrophic factor = maintains medullary
dopaminergic neurons in vitro
c. Nerve Growth factor = necessary for the growth and maintenance of
sympathetic neurons
d. Leukemia inhibitory factor = enhances growth of neurons
11. The contractile mechanism in skeletal muscle largely depends all of the following
proteins except:
a. myosin-II
b. myosin-I
c. actin
d. tropomyosin
12. Regarding skeletal muscle, which of the following equilibrium potentials (mV) is
incorrectly paired with its ion?
a.H+
+32
b. K+
-95
c. Cl-90
d. HCO3
-32
13. Which of the following is not a property of Type IIA skeletal muscle fibre types?
a. red colour
b. large diameter
c. resistant to fatigue
d. moderate glycolytic capacity
14. Regarding heat production in muscles, which of the following is incorrect?
a. relaxation heat = external manifestation of basal metabolic processes
b. activation heat = produced from muscle contraction
c. shorting heat = produced from structural change in muscle while shortening
d. 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. sarcolemma
b. sarcoplasmic reticulum
c. Terminal cistern
d. intercalated discs
16. Which of the following neurotransmitter is correctly colocalized with a
neuropeptide?
a. Acetylcholine – cholecystokinin
b. Serotonin – neurotensin
c. glutamate – substance P
d. glycine – cholecystokinin
17. Which of the following neurotransmitter does not use cyclic AMP as a second
messenger?
a. Glutamate
b. Serotonin
c. Dopamine
d. 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 sarcomere
b. the thin filaments are made up of actin, tropomyosin and troponin
c. the thick filaments are made up of myosin
d. 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 COMT
b. dopaminergic neurons are located in the nigrostriatal system
c. active reuptake occurs via Cl- dependent dopamine transporter
d. overstimulation of D2 receptors is thought to be causal in schizophrenia
20. During muscle contraction, which of the following is not true?
a. Ca2+ efflux
b. 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
detach
d. 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 passive
b. ATP provides the energy for relaxation whereas contraction is passive
c. ATP provides the energy for both contraction and relaxation
d. 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
system
b. unitary smooth muscle contraction is synchronised by gap junction
communication
c. multiunit smooth muscle contraction can occur voluntarily via coordinated
motor units
d. Ca2+ regulation of contraction is primarily through phosphyorylationdephosphylation reactions
23. Which is false with respect to Serotonin:
a. is present in highest concentration in blood platelets
b. the principal urinary metabolite is 5-HIAA (5-hydroxyindoleacetic acid)
c. can be found in the midline raphe nuclei of the brain stem
d. 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. diuresis
b. analgesia
c. constipation
d. miosis
25. Regarding sense organs, which is true?
a. Meissner corpuscle responds to changes in texture
b. Merkel cells respond to intermittent pressure
c. Pacinian corpuscles respond to slow vibration
d. 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 fibres
b. there are two nuclear bag fibres per muscle spindle
c. have a motor nerve supply of their own
d. 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 reflex
b. it occurs in response to painful stimuli
c. 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 reflex
b. there are 3-25 muscle fibres per tendon organ
c. involved in regulation of the velocity of the muscle contraction
d. 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 T
b. there is always a decrease in the length of the muscle
c. if it is an isotonic contraction, work is done
d. 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 cells
b. is increased with increased external Na+ concentration
c. implies that the inside of the cell is positive relative to the outside of the cell
at rest
d. 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 adaptation
b. threshold intensity is required to be reached for production of an action
potential
c. stimulus size will lead to variable action potential amplitude and form
d. threshold intensity varies with duration of stimulus
32. Regarding muscular dystrophies, which is correct?
a. Becker muscular dystrophy is an absence of dystrophin
b. Duchenne muscular dystrophy is an absence of dystrophin
c. Dystrophin is present but altered in Duchenne muscular dystrophy
d. 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 msec
b. Calcium is essential for neurotransmitter release
c. the synaptic cleft is 20 – 40 nm wide
d. there are four kinds of synaptic vesicles
34. Regarding EPSPs and IPSPs, which is incorrect?
a. IPSP is due to increased chloride transport
b. EPSP is facilitated by sodium and calcium channel opening
c. IPSP can be due to potassium channel opening
d. 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 acid
b. all catecholamines are synthesized from tyrosine
c. Epinephrine can only be produced in the adrenal medulla
d. Tryptophan undergoes hydroxylation in the steps to produce serotonin
36. Regarding nociceptors, which is incorrect?
a. Tickle and itch are related to pain sensation
b. Bradykinin activates both Aδ and C fibres
c. Histamine is more likely to produce itch than kinins
d. 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 dystrophy
c. 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 hand
b. The mouth
c. The trunk and back
d. The thumb
39. A lesion at the optic chiasm results in:
a. homonymous hemianopia
b. heteronymous hemianopia
c. homonymous hemianopia with sparing of the fibres from the macula
d. blindness in one eye
40. Nystagmus
a. is initiated by visual impulses
b. is not present in blind individuals
c. can be horizontal, vertical or rotatory
d. 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 astrocytes
b. Fibrous astrocytes are found predominatly in grey matter
c. Protoplasmic astrocytes produce substances that are trophic to neurons
d. 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 stimuli
b. Action potentials (nerve impulses) are conducted passively
c. Potential differences occur when there is equal distribution of ions
across the cell membrane
d. Only propagated potentials occur in neurons
44. Regarding Ionic flux, which is correct?
a. Na concentrations are higher inside the cell
b. K channel opening is slower and more prolonged that Na channel
opening
c. Na channel opening causes repolarisation
d. 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 conduction
b. Smaller diameter nerve fibres have a greater speed of conduction
c. Nerve fibres are divided into A, B, C and D groups
d. 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 body
b. Neurotrophins only act at TRK receptors
c. NGF (Nerve Growth Factor) is necessary for growth and maintenance
of sympathetic neurons
d. 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 20-40nm
b) there are small vessels with a dense core that contain catecholamines
c) the vesicles are transported to the nerve ending by fast axoplasmic
transport
d) 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
decay
d) 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 Potential
b) Opening of Cl- channels causes an Inhibitory Postsynaptic Potential
c) Closing of Na+ channels causes an Excitatory Post synaptic Potential
d) 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 present
b) Postganglionic neurons branch extensively and innervate multiple smooth
muscle cells
c) Denervation does not lead to atrophy
d) 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 NMJ
c) Causes spastic paralysis
d) 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. kidney
b. liver
c. gallbladder
d. 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 motility
b. the enteric nervous system contains about half as many neurons as the
spinal cord
c. the submucosal plexus is located between the circular muscle and the
luminal mucosa
d. the myenteric plexus is located between the longitudinal and circular layers
of muscle
54.
Which of the following is not an acetylcholinesterase inhibitor?
a. physostigmine
b. parathion
c. diisopropyl fluorophosphates
d. hexamethonium
55.
What is the amount of insensible water loss in the average human in milliliters
per hour?
a. 40 ml/h
b. 50 ml/hr
c. 60 ml/hr
d. 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 C
b. in individuals who sleep at night, the human body temperature is highest in
the late morning
c. the oral temperature is normally 1.5 degrees C lower than the rectal
temperature
d. 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 cell
b. Pacinian corpuscle
c. Ruffini endings
d. Schwann cell
58. Which of these is not a sensory receptor classification?
a. Nocioreceptor
b. Adrenoreceptor
c. Mechanoreceptor
d. Photoreceptor
59. Which of these is untrue about a stretch reflex?
a. A stretched muscle will contract
b. The sensory organ is the muscle spindle
c. Not all reflex arcs involve the CNS
d. The synapse neurotransmitter is usually glutamate
60. Regarding the knee jerk reflex, which is true?
a. Is a polysynaptic stretch reflex
b. Hyperactive reflex signifies an interruption in the spinothalamic tract
c. Absence of the reflex signifies an abnormality in the muscle spindles
d. Most common cause of hyperactivity is peripheral neuropathy due to
diabetes or alcohol
e.
61. What is the correct order of the reflex arc?
a. Sensory organ – afferent neuron – synapse – efferent neuron – effector
response
b. Sensory organ – synapse – afferent neuron – efferent neuron – effector
response
c. Sensory organ – efferent neuron – afferent neuron – synapse – effector
response
d. None of these
62. Which of the following cells are not found in the central nervous system?
a. Oligodendrocytes
b. Schwann cells
c. Microglia
d. 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 potential
b. 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 potential
d. 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 channels
b. Reversal of the electrical Na gradient during overshoot
c. Opening of voltage-gated K channels
d. 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 sympathetic
b. Aδ – Motor to muscle spindles
c. B – Preganglionic autonomic
d. Aα – Somatic motor
66. Which of the following nerve fibre types is most susceptible to local anaesthetics?
a. Aα
b. B
c. Aβ
d. C
67. The following neurotransmitters are synthesised from tyrosine except:
a. Dopamine
b. Norepinephrine
c. Glutamate
d. 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 ligand
c. Prolonged exposure to ligands causes decreased receptor response
d. 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 receptors
c. ACh is reuptaken into the pre-synaptic knob unchanged
d. Muscarinic receptors are mainly found in the peripheral nervous system
70. The following neurotransmitters are inactivated by monoamine oxidase (MAO)
except:
a. Acetylcholine
b. Epinephrine
c. Dopamine
d. Serotonin
71. Which of the following is not an effect of stimulation of the µ opiate receptor?
a. Constipation
b. Hyperventilation
c. Miosis
d. Euphoria
72. The Bell-Magendie law states:
a. Spinal cord dorsal roots are motor
b. Spinal cord ventral roots are sensory
c. Spinal cord dorsal roots are sensory
d. Stretch reflexes are all monosynaptic
73. Regarding monosynaptic reflexes:
a. Intrafusal fibres are at right angles to extrafusal fibres
b. The two types of sensory endings in spindles are Ib and II
c. Spindles themselves have no motor supply
d. The neurotransmitter at the central synapse is glutamate
74. Which of the following is NOT a type of pain receptor?
a. Stretch nocireceptor
b. Mechanical nocireceptor
c. Thermal nocireceptor
d. Polymodal nocireceptor
75. Referred pain
a. Always refers to a single dermatome
b. Can refer to the opposite side of the body
c. Is not useful in the clinical setting
d. Is best described by the Divergence-Projection theory
76. Regarding the withdrawal reflex
a. A flexor response is predicted in the contralateral limb
b. Monosynaptic transmission is typical
c. Reverberating circuits are uncommon
d. 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. Acetylcholine
b. Dopamine
c. Norepinephrine
d. Histamine
78. Activation of which receptor would be expected to decrease anxiety?
a. Glutamate
b. GABAA
c. 5HT3
d. Nicotinic cholinergic
79. Which reaction is incorrect?
a. Choline acetyltransferase catalyses formation of acetylcholine
b. Histamine formed by decarboxylation of histadine
c. Tyrosine to Dopa by dopa β-hydroxylase
d. 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 hydroxylase
b. A drug that inhibits dopamine β-hydroxylase
c. A drug that inhibits monoamine oxidase
d. A drug that inhibits norepinephrine reuptake
82. Which is true of Duchenne muscular dystrophy?
a. Dystrophin protein is absent from muscle
b. Is usually fatal by the age of 12
c. Is not x-linked
d. 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 glycolytic
b. Type 11A is fast oxidative/glycolytic
c. Type 11B is fast oxidative
d. 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 lines
b. Myosin is the thin filament
c. Actin is the thin filament
d. 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 potential
b. Is followed by relaxation
c. Starts about 2 ms after the start of membrane depolorisation
d. 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 supplies
b. In the hand one motor unit innervates ~600 muscle fibres
c. Each motor neuron innervates several types of muscle fibres
d. The recruitment of motor units is random.