Chapter: Nerves and Muscles
1.

With reference to the action potential:

A. decreasing the external Na+ concentration increases the size of the action potential
B. decreasing the external K+ concentration decreases the resting membrane potential
C. increasing the external Na+ concentration decreases the resting membrane potential
D. decreasing the external K+ concentration has little effect on the resting membrane potential
E. none of the above are true
Answer» E. none of the above are true
2.

In the Erlanger and Gasser classification of nerve fibres:

A. C fibres have the fastest conduction velocity
B. Aγ fibres are responsible for touch and pressure
C. C fibres are most susceptible to local anaesthetics
D. Aα fibres have the fastest conduction velocity and the longest absolute refractory period
E. A fibres are most susceptible to hypoxia
Answer» C. C fibres are most susceptible to local anaesthetics
3.

Regarding neurotrophins:

A. NGF and BDNF share the same receptor
B. the structure of the β subunit of NGF resembles that of insulin
C. CNTF is necessary for the growth and maintenance of sympathetic neurons
D. disruption of GDNF by gene knockout causes a marked loss of cutaneous mechanoreceptors
E. none of the above are true
Answer» B. the structure of the β subunit of NGF resembles that of insulin
4.

Regarding cardiac muscle:

A. cardiac muscle has high ATPase activity
B. only the α MHC isoform is found in the atria
C. resting membrane potential is about -70mV
D. force of contraction is mediated by catecholamines acting via β1 -adrenergic receptors
E. mutations of the human ether-a-go-go gene causes minks to shake their legs uncontrollably
Answer» D. force of contraction is mediated by catecholamines acting via β1 -adrenergic receptors
5.

Which of the following does not decrease smooth muscle membrane potential?

A. acetylcholine
B. stretch
C. cold
D. noradrenaline
E. parasympathetic stimulation
Answer» D. noradrenaline
6.

In regard to plasma volume:

A. it contributes to 10% of body weight
B. can easily be measured by radioisotope chromium
C. if the plasma volume is known, the blood volume can be calculated by multiplying100-HCT/100
D. measured by injecting Evans blue
E. the average plasma volume is 500ml
Answer» D. measured by injecting Evans blue
7.

Which of the following is FALSE?

A. the ECF represents 20% of body weight
B. the blood volume represents 8% of the body weight
C. the 2/3 of the body water is in ICF
D. 18% of the body weight is protein
E. the transcellular fluids contribute to 5% of the body weight
Answer» E. the transcellular fluids contribute to 5% of the body weight
8.

Which of the following is FALSE?

A. diffusion depends on concentration gradient of the solutes
B. osmotic pressure of a solution is inversely related to the volume of the solution
C. when 5% dextrose is infused, it becomes hypotonic to the plasma in the body
D. osmolality is defined as osmotically active particles in 1L of solution
E. osmolality is defined as a number of osmotically active particles in 1kg of solvent
Answer» D. osmolality is defined as osmotically active particles in 1L of solution
9.

Regarding cell membrane, which of the following is FALSE?

A. the diameter of the cell membrane is about 7.5nm
B. 50% of the cell membrane is made up of proteins
C. the main lipids of the cell membrane are phospholipids
D. the hydrophilic ends of the lipid molecules are faced towards the interior of the cell membrane
E. the proteins in the cell membrane function as carriers, ion channels, enzymes and receptors
Answer» D. the hydrophilic ends of the lipid molecules are faced towards the interior of the cell membrane
10.

Regarding mitochondria, which of the following is TRUE?

A. 99% of mitochondrial proteins are products of mitochondrial DNA
B. the outer membrane of the mitochondria is folded to form cristae
C. the space between the outer and inner mitochondrial space is called matrix space
D. it is the sperm which contributes to the formation of mitochondria in the zygote
E. the synthesis of ATP in the mitochondria is triggered by diffusion of H+ from matrix to intracristal space
Answer» E. the synthesis of ATP in the mitochondria is triggered by diffusion of H+ from matrix to intracristal space
11.

Which is FALSE?

A. fast fibres have small number of mitochondria
B. fast fibres are called white muscles
C. the glycolic processes are more important in energy supply in fast fibres
D. slow fibres are also called red fibres
E. fast fibres have more extensive blood supply than slow fibres
Answer» E. fast fibres have more extensive blood supply than slow fibres
12.

Smooth muscles differ from skeletal muscle by:

A. not having actin/myosin
B. not having striated appearance
C. not using ATP for contraction
D. not using Ca2+ for contraction
E. not having sarcoplasmic reticulum
Answer» B. not having striated appearance
13.

Which of the following is absent in smooth muscle?

A. tropomysin
B. actin
C. myosin
D. troponin
E. mitochondria
Answer» D. troponin
14.

The highest number of voltage gated Na+ channels are found in:

A. initial segment of axon
B. nodes of Ranvier
C. cell body
D. terminal buttons
E. myeline sheath
Answer» A. initial segment of axon
15.

Which of the following nerve fibres is most susceptible to hypoxia?

A. group B
B. group C
C. group A – α
D. dorsal root
E. somatic motor
Answer» A. group B
16.

Which of the following is most susceptible to pressure?

A. group A – motor
B. group C
C. group B
D. pre ganglionic-autonomic
E. muscle spindle fibres
Answer» A. group A – motor
17.

Regarding nerve action potential, which is TRUE?

A. normal resting membrane potential is -40mV
B. initial rapid depolarisation is due to rapid influx of Ca2+ via fast channels
C. during depolarisation, Na+ permeality is greater than K+ permeality
D. hyperpolarisation is due to continuous opening of Na+ channels
E. plateau is formed by slow Ca2+ channels
Answer» C. during depolarisation, Na+ permeality is greater than K+ permeality
18.

Which is FALSE regarding secondary active transport?

A. it always transports substances in one direction
B. energy required is obtained by Na+ /K+ ATPase pump
C. a good example is Na+ / glucose co-transport
D. Na+ / Ca2+ antiport is an example of secondary active transport
E. secondary active transport occurs in renal tubules
Answer» A. it always transports substances in one direction
19.

Which is TRUE?

A. steroids act via cAMP
B. insulin acts via IP3
C. EGF+ erythropoietin act via cAMP
D. thyroid hormones act via G proteins
E. retinoic acid act via intracellular receptor → transcription of genes
Answer» E. retinoic acid act via intracellular receptor → transcription of genes
20.

Na+ / K+ ATPase pump – which is FALSE?

A. it is electrogenic in nature
B. it is important in maintaining cell volume
C. plays a major role in secondary active transport
D. it is the main factor which determine the resting membrane potential
E. it is an example of primary active transport
Answer» D. it is the main factor which determine the resting membrane potential
21.

Regarding serotonin:

A. the highest concentration is in the brain
B. formed by hydroxylation and decarboxylation of tyrosine
C. catabolised by COMT
D. some receptors are ion channels
E. mediates smooth muscle relaxation
Answer» D. some receptors are ion channels
22.

GABA:

A. decreases Cl- conductance
B. is broken down by glutamate decarboxylase (GA????)
C. there are five receptor subtypes
D. benzodiazepines bind to the β subunit of the GABA receptor
E. is involved in 20% of CNS synapses
Answer» E. is involved in 20% of CNS synapses
23.

Which is NOT present in high concentrations, at the active zone of synapses?

A. syntaxin
B. catecholamine vesicles
C. neuropeptide vesicles
D. synaptobrevin
E. calcium channels
Answer» C. neuropeptide vesicles
24.

Which is not a ligand-gated ion channel?

A. nicotinic receptor
B. GABAA receptor
C. glycine receptor
D. NMDA receptor
E. 5-HT1 receptor
Answer» E. 5-HT1 receptor
25.

Which drug is NOT involved in facilitating Cl- conductance?

A. benzodiazepines
B. progesterone
C. oestrogen
D. barbiturates
E. alcohol
Answer» C. oestrogen
26.

Regarding skeletal muscle:

A. isotonic contraction does no work
B. calcium is released from troponin during contraction
C. the resting membrane potential is -70mV
D. treppe occurs in skeletal muscle only
E. white muscle has short twitch durations
Answer» E. white muscle has short twitch durations
27.

Regarding cardiac muscle:

A. gap junctions provide high resistance bridges
B. T system of tubules located at A-I junctions
C. calcium binds to calmodulin
D. tetany is not possible due to the latch bridge mechanism
E. ↑cAMP leads to ↑ force of contraction
Answer» E. ↑cAMP leads to ↑ force of contraction
28.

Regarding smooth muscle:

A. tropomyosin is absent
B. the resting membrane potential is -90mV
C. there is a highly developed sarcoplasmic reticulum
D. there are no spike potentials
E. dense bodies are attached to the cell membrane
Answer» E. dense bodies are attached to the cell membrane
29.

Regarding synapses:

A. large vesicles contain ACh
B. Na+ influx triggers fusion / exocytosis of vesicles
C. I PSP can be produced by closing K channels
D. the synaptic cleft is 100-150nm
E. neurotransmitters migrate down the axon by fast axoplasmic transport
Answer» E. neurotransmitters migrate down the axon by fast axoplasmic transport
30.

Regarding acetylcholine:

A. it is oxidised to choline and acetate by acetylcholinesterase
B. nicotinic receptors are blocked by atropine
C. it is the main excitatory transmitter in the spinal cord
D. it is secreted by the adrenal medulla
E. tetanus blocks its release at the NMJ
Answer» E. tetanus blocks its release at the NMJ
31.

Regarding synaptic structure / function:

A. small clear vesicles in the presynaptic tunnel contain catecholamines
B. tetanus toxin causes spastic paralysis by blocking release of ACh at NMJ
C. chemical mediators located in ???? of presynaptic fibres contain one-way conduction of impulses
D. the EPSP is an all-or-none response
E. An I-PSP can be produced by localised increase in membrane permeability to Cl-
Answer» C. chemical mediators located in ???? of presynaptic fibres contain one-way conduction of impulses
32.

Transmitters – all are true EXCEPT:

A. angiotensin II is a neurotransmitter of the polypeptidillars
B. glutamate is an inhibitory amino acid
C. glucagons is found in hypothalamus and retina
D. vasopressin is found in posterior pituitary, medulla, spinal cord
E. serotonin is an amine
Answer» B. glutamate is an inhibitory amino acid
33.

Neurotransmitters:

A. atropine blocks effect of acetylcholine at ???? receptor
B. reaction between active acetate and choline is catalysed by acetylcholinesterase
C. nicotinic cholinergic receptors are serpentine receptors
D. the rate limiting step in synthesis of NOVA is ?????(concussion) of tyrosine to dopa
E. MAOA is found in nerve endings and platelets
Answer» D. the rate limiting step in synthesis of NOVA is ?????(concussion) of tyrosine to dopa
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