57 clinical MCQs in Physiology. Sensory receptors are classified functionally according to the following criteria, except. Kenya, Africa and global revi...
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Q1. Sensory receptors are classified functionally according to the following criteria, except ---
- their location in the body
- the nature of tissues in which they are found
- the nature of stimuli acting on them
- their connection with cerebral cortex
- none of the above
Answer: their location in the body
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Q2. A specific stimulus produces a receptor potential by ---
- inhibiting Na + influx into receptor
- inhibiting K + efflux from receptor
- enhancing Na + influx into receptor
- enhancing K + efflux from receptor
- Blocking the $\text{Ca}^{2+}$ channel
Answer: inhibiting Na + influx into receptor
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Q3. The following is false; detection of the stimulus modality depends upon ---
- the location of the receptors in the body
- the magnitude of the stimulus
- the anatomical connections between the receptors and specific sensory areas in the cerebral cortex
- the magnitude of the receptor potential
- Descending input
Answer: the location of the receptors in the body
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Q4. The brain interprets signals from the eye as light even if the eye is actually being stimulated by something else, such as pressure. This best describes ---
- sensory adaptation
- the law of specific nerve energies
- the pupillary reflex
- The law of projection
- All or nothing law
Answer: sensory adaptation
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Q5. The two-point touch threshold test serves as a demonstration of ---
- lateral inhibition.
- sensory adaptation
- receptive fields.
- the law of projection
- Nerve energies
Answer: lateral inhibition.
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Q6. The following statements are true of synaptic transmission except ---
- A synapse is a junction between two excitable tissues
- The pre-synaptic cell terminates on the soma, dendrites or axon of the post synaptic cell.
- Transmission at the synapse is always via a chemical.
- Transmission from Nerve to muscle resembles chemical synapse
- A Neurotransmitter has receptors on the post-synaptic membrane.
Answer: A synapse is a junction between two excitable tissues
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Q7. With regards to a chemical synapse the following is true except ---
- Calcium ion is essential for transmission
- The action potential opens ligand-gated channels
- Neurotransmitter is packaged in clear vesicles
- Biodegradation takes place in the pre-synaptic cell
- There are receptors on the pre-synaptic membrane
Answer: Calcium ion is essential for transmission
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Q8. In the synthesis of Neurotransmitter the following is true except ---
- Energy is sometimes used
- Substrates are found in the cytosol
- Substrates are found in the extracellular fluid compartment
- It takes place in the extracellular fluid compartment
- The process may be interfered with by the biodegrading enzyme
Answer: Energy is sometimes used
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Q9. The following statement are true of packaging and release of neurotransmitter except ---
- It's packaged against a PH gradient
- The packaging is energy dependent
- Release is by a process of exocytosis
- Ca 2+ plays a major role
- Release is by a Na+ dependent mechanism
Answer: It's packaged against a PH gradient
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Q10. With regard to receptors in chemical synaptic transmission the following is true except ---
- They are found on the pre-synaptic membrane.
- They are found on the post-synaptic membrane
- They are all G-protein coupled
- They are ligand-gated
- They are specific for a specific neurotransmitter
Answer: They are found on the pre-synaptic membrane.
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Q11. Which of the following statements correctly refers to parasympathetic neurons ---
- Adrenergic all the way.
- Mass discharge.
- Thoraco-lumbar outflow.
- Emerge from the cranial-sacral regions.
- Ganglia form sympathetic chain.
Answer: Adrenergic all the way.
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Q12. Which list of neurons below are not cholinergic? ---
- Postganglionics supplying sweat glands.
- Preganglionic sympathetic fibers.
- Postganglionic sympathetic fibers.
- Preganglionic parasympathetic fibers.
- Postganglionic parasympathetic fibers.
Answer: Postganglionics supplying sweat glands.
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Q13. For which transmitter is tyrosine substrate in the synthetic pathway? ---
- acetylcholine.
- histamine.
- glutamate.
- dopamine.
- serotonin.
Answer: acetylcholine.
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Q14. Neurotransmitter termination may involve the following processes except ---
- digestion.
- recycling components.
- re-synthesis.
- re-uptake.
- diffusion.
Answer: digestion.
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Q15. Which of the following is an $\alpha$-adrenergic response? ---
- skin vasodilation.
- dilation of the airways.
- watery salivation.
- increased cardiac contraction.
- contraction of gastrointestinal sphincters
Answer: skin vasodilation.
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Q16. Which of the following events occurs before depolarization of the T tubules in skeletal muscle in the cell mechanism of excitation-contraction coupling? ---
- Depolarization of the sarcolemmal membrane
- Opening of Ca2+ release channels on the sarcoplasmic reticulum (SR)
- Uptake of Ca2+ into the SR by Ca2+-adenosine triphosphatase (ATPase)
- Binding of Ca2+ to troponin C
- Binding of actin and myosin
Answer: Depolarization of the sarcolemmal membrane
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Q17. Initiation of an action potential in skeletal muscle by stimulating its motor nerve ---
- Requires spatial facilitation
- Requires temporal facilitation
- Is inhibited by a high concentration of Ca2+ at the neuromuscular junction
- Requires the release of norepinephrine
- Requires the release of acetylcholine
Answer: Requires spatial facilitation
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Q18. Which characteristic or component is shared by skeletal muscle and smooth muscle? ---
- Thick and thin filaments arranged in sarcomeres
- Troponin
- Elevation of intracellular [Ca2+] for excitation-contraction coupling
- Spontaneous depolarization of the membrane potential
- High degree of electrical coupling between cells
Answer: Thick and thin filaments arranged in sarcomeres
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Q19. Repeated stimulation of a skeletal muscle fiber causes tetanic contraction because the intracellular concentration of which solute increases and remains at high levels? ---
Answer: Na+
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Q20. A person with myasthenia gravis notes increased muscle strength when he is treated with an acetylcholinesterase (AChE) inhibitor. The basis for his improvement is increased ---
- Amount of acetylcholine (ACh) released from motor nerves
- Levels of ACh at the muscle end plates
- Number of ACh receptors on the muscle end plates
- Amount of norepinephrine released from motor nerves
- Synthesis of norepinephrine in motor nerves
Answer: Amount of acetylcholine (ACh) released from motor nerves
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Q21. In skeletal muscle ---
- tropomyosin is made up of 3 subunits
- the heads of actin contain an ATP hydrolysis site
- the myosin is contained entirely within the A band
- troponin T inhibits the interaction with myosin
- the immediate energy source for contracting is GTP
Answer: tropomyosin is made up of 3 subunits
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Q22. The special feature of the contraction of smooth muscle is that ---
- actin is not involved
- myosin is not involved
- calcium is not involved
- ATP is not the energy source
- the membrane potential is unstable
Answer: actin is not involved
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Q23. Myoglobin ---
- binds oxygen for aerobic respiration with the muscle cell;
- binds actin to myosin;
- blocks myosin binding sites;
- stores ATP;
- separates one sarcomere from another.
Answer: binds oxygen for aerobic respiration with the muscle cell;
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Q24. When a muscle cell contracts: ---
- actin slides past myosin;
- myosin slides past actin;
- Ca++ ions are removed from the sarcoplasm;
- crossbridges rotate so that the myosin filaments fold in half.
- sarcomeres increase in size
Answer: actin slides past myosin;
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Q25. The simple stretch reflex is characterized by all of the following properties except: ---
- disynaptic reflex
- high localization
- shows reciprocal innervations.
- it is of graded response.
- it is a monosynaptic reflex
Answer: disynaptic reflex
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Q26. Muscle spindles : ---
- are found in all skeletal muscles
- are found only in large skeletal muscles
- consist of small numbers of extrafusal muscle fibers
- consist of a large number of extrafusal muscle fibers
- contain a number of primitive smooth muscle fibers
Answer: are found in all skeletal muscles
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Q27. $\gamma$ motor innervation of muscle spindles produces : ---
- contraction of the central region of the spindle fibers
- increased sensory discharge from the central region of the spindle fibers
- decreased sensory discharge from the central region of the spindle fibers
- relaxation of the peripheral regions of the spindle fibers
- relaxation of the extrafusal fibers
Answer: contraction of the central region of the spindle fibers
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Q28. Discharge from muscle spindles could be increased by all the following, except : ---
- increased $\alpha$ motor neuron discharge
- increased $\gamma$motor neuron discharge
- stretch of the intrafusal muscle fibers
- stretch of the extrafusal muscle fiber
- increased stretch of muscle
Answer: increased $\alpha$ motor neuron discharge
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Q29. Co activation of $\alpha$ and $\gamma$ motor neurons ---
- increases $\gamma$ motor neuron discharge whenever the activity of $\alpha$ motor neurons rises to a high level
- is mediated by interneurons that link the $\alpha$ and $\gamma$ motor neurons
- maintains the proprioceptive information to higher centers during muscle contraction
- increases the $\alpha$ motor neuron discharge whenever the activity of $\gamma$ motor neurons rises to a high level
- none of the above
Answer: increases $\gamma$ motor neuron discharge whenever the activity of $\alpha$ motor neurons rises to a high level
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Q30. Inverse stretch reflex ---
- increases the possibility of avulsion of the excessively stretched muscle from its bony attachments
- has no reciprocal innervation circuits
- is clinically manifested by lengthening reaction
- is clinically tested by examining the tendon jerks
- it is normally initiated by muscle stretch
Answer: increases the possibility of avulsion of the excessively stretched muscle from its bony attachments
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Q31. Presynaptic inhibition depends upon ---
- augmented release of chemical transmitter from presynaptic terminals
- continued depolarization of presynaptic terminals
- GABA receptors in presynaptic terminals
- opening of voltage-gated Ca ++ channels in presynaptic terminals
- release of glutamate at the synaptic cleft
Answer: augmented release of chemical transmitter from presynaptic terminals
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Q32. Postsynaptic receptors include all the following types, except ---
- G-protein coupled receptors
- ligand-gated cation channels
- G protein regulated K + channels
- voltage-gated Cl channels
- all of the above are examples of receptors
Answer: G-protein coupled receptors
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Q33. Theligand-Gated ion channels open. The Synaptic vesicles release neurotransmitter into the synaptic cleft. Which Sequence of events is correct? ---
- 1→2→3→4→5
- 2→3→5→4→1
- 3→2→5→1→4
- 4→3→1→2→5
- 5→1→2→4→3
Answer: 1→2→3→4→5
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Q34. Assume That excessive consumption of ethanol increases the influx of negative chloride ions into "Common sense" neurons whose action potentials are needed for you to act appropriately and not harm yourself or others Thus, Any resulting poor decisions associated with ethanol ingestion are likely due to ---
- increased Membrane depolarization of " Common sense " neurons.
- decreased Membrane depolarization of " Common sense" neurons.
- more Action potentials in your "Common sense" neurons.
- more EPSPs In your "Common sense" neurons.
- fewer IPSPs In your "Common sense" neurons
Answer: increased Membrane depolarization of " Common sense " neurons.
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Q35. An inhibitory postsynaptic potential (IPSP) is associated with . ---
- bringing the threshold closer to the resting membrane potential
- opening of voltage-regulated channels
- a change in sodium ion permeabilit y
- hyperpolarization
- depolarization
Answer: bringing the threshold closer to the resting membrane potential
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Q36. Which of the following is not a polysynaptic reflex? ---
- plantar reflex
- withdrawal reflex
- crossed-extensor reflex
- stretch reflex
- Golgi tendon reflex
Answer: plantar reflex
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Q37. A reflex action ---
- Is initiated at a sensory receptor organ.
- May result in endocrine secretion.
- Involves transmission across at least two central nervous synapses in series.
- May be excitatory or inhibitory.
- Is independent of higher centres in the brain.
Answer: Is initiated at a sensory receptor organ.
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Q38. In skeletal muscle neuromuscular junctions ---
- The motor end plate is the motor nerve terminal.
- Spontaneous (miniature) potentials may be recorded in the motor nerve terminal.
- Motor nerve terminals have vesicles containing acetylcholine.
- There is a high concentration of acetylcholinesterase.
- Transmission is facilitated by botulinum toxin.
Answer: The motor end plate is the motor nerve terminal.
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Q39. Cerebrospinal fluid ---
- Is formed in the arachnoid granulations.
- Provides the brain with most of its nutrition.
- Protects the brain from injury when the head is moved.
- Has a lower pressure than that in the cerebral venous sinuses.
- Flow around the adult brain is around half a litre per day.
Answer: Is formed in the arachnoid granulations.
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Q40. In sensory receptors ---
- Stimulus energy is converted into a local depolarization.
- The generator potential is graded and self-propagating.
- A generator potential can be produced by only one form of energy.
- The frequency of action potentials generated doubles when the strength of the stimulus doubles.
- Serving touch sensation, constant suprathreshold stimulation causes action potentials to be generated at a constant rate.
Answer: Stimulus energy is converted into a local depolarization.
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Q41. A somatic lower motor neurone ---
- Innervates fewer fibres in an eye muscle than does one innervating a leg muscle.
- Conducts impulses at a speed similar to that in an autonomic postganglionic neurone.
- Is unmyelinated.
- Conducts impulses which cause relaxation in some skeletal muscles.
- Synapse with skeletal muscle but not with other neurones.
Answer: Innervates fewer fibres in an eye muscle than does one innervating a leg muscle.
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Q42. A skeletal muscle fibre ---
- Membrane is negatively charged on the inside with respect to the outside at rest.
- Contains intracellular stores of calcium ions.
- Is normally innervated by more than one motor neurone.
- Becomes more excitable as its resting membrane potential falls.
- Becomes less excitable as the extracellular ionized calcium levels fall.
Answer: Membrane is negatively charged on the inside with respect to the outside at rest.
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Q43. An excitatory post-synaptic potential ---
- Is the depolarization of a post-synaptic nerve cell membrane that occurs when a pre-synaptic neurone is stimulated.
- Involves reversal of polarity across the post-synaptic nerve cell membrane.
- May be recorded from a posterior root ganglion cell.
- Is propagated at the same rate as an action potential.
- Is caused by the electrical field induced by activity in the pre-synaptic nerve terminals.
Answer: Is the depolarization of a post-synaptic nerve cell membrane that occurs when a pre-synaptic neurone is stimulated.
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Q44. Sympathetic ---
- Ganglionic transmission is mediated by acetylcholine.
- Neuromuscular transmission at the heart is mediated by adrenaline.
- Neuromuscular transmission in hand skin arterioles is mediated by acetylcholine.
- Neuroglandular transmission at sweat glands is mediated by noradrenaline.
- Neuromuscular transmission at the iris is mediated by noradrenaline.
Answer: Ganglionic transmission is mediated by acetylcholine.
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Q45. The blood-brain barrier ---
- Slows equilibration of solutes between blood and brain tissue fluids.
- Is a more effective barrier for fat-soluble substances than water-soluble substances.
- Is a more effective barrier in infants than in adults.
- Is a more effective barrier for CO 2than for O 2.
- Permits hydrogen ions to pass freely. f) None of the above
Answer: Slows equilibration of solutes between blood and brain tissue fluids.
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Q46. Parasympathetic nerves ---
- Have opposite effects to sympathetic nerves on intestinal smooth muscle.
- Have opposite effects to sympathetic nerves on iris smooth muscle.
- Cause vasodilatation in skeletal muscle during prolonged exercise.
- Cause sweat secretion in skin when body temperature rises.
- Have longer postganglionic than preganglionic fibres.
Answer: Have opposite effects to sympathetic nerves on intestinal smooth muscle.
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Q47. Visceral smooth muscle differs from skeletal muscle in that ---
- It contracts when stretched.
- It is not paralyzed when its motor nerve supply is cut.
- Its cells have unstable resting membrane potentials.
- It contains no actin or myosin.
- Excitation depends more on influx of extracellular calcium than release of calcium from endoplasmic reticulum.
Answer: It contracts when stretched.
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Q48. An inhibitory post-synaptic potential ---
- May be recorded in a post-ganglionic sympathetic neurone.
- May be recorded in an anterior horn motor neurone.
- Does not exceed one millivolt in amplitude.
- Moves membrane potential towards the equilibrium potential for potassium.
- May summate in space and time with other excitatory and inhibitory potentials in the same neuron.
Answer: May be recorded in a post-ganglionic sympathetic neurone.
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Q49. A volley of impulses travelling in a pre-synaptic neurone causes ---
- An identical volley in the post-synaptic neurone.
- An increase in the permeability of the pre-synaptic nerve terminals to calcium.
- Vesicles in the nerve endings to fuse with the cell membrane and release their contents.
- The generation of at least one action potential in the post-synaptic neurone.
- Neurotransmitter to travel down the nerve axon.
Answer: An identical volley in the post-synaptic neurone.
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Q50. A property shared by: ---
- Skeletal and cardiac muscle is their striated microscopical appearance.
- Skeletal and multiunit smooth muscle is that they are paralysed when their motor nerves are cut.
- Cardiac and visceral smooth muscle is their spontaneous activity when denervated.
- Skeletal and cardiac ventricular muscle is their stable resting membrane potential.
- All varieties of muscle is that contraction strength is related to their initial length.
Answer: Skeletal and cardiac muscle is their striated microscopical appearance.
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Q51. Histological and physiological study of skeletal muscle shows that the ---
- Distance between two Z lines remains constant during contraction.
- Width of the anisotropic A band is constant during contraction.
- Tension developed is maximal when actin and myosin molecules just fail to overlap.
- Stimulus needed to cause contraction is minimal when applied at the Z line.
- The T system of transverse tubules opens into the terminal cisterns of the sarcoplasmic reticulum.
Answer: Distance between two Z lines remains constant during contraction.
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Q52. Blockade of parasympathetic activity causes a reduction in ---
- Sweat production.
- Resting heart rate.
- The strength of skeletal muscle contraction.
- Salivation.
- Intestinal motility.
Answer: Sweat production.
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Q53. Endurance training increases the muscle's capacity to: ---
- contract faster
- breakdown phosphocreatine
- burn fat and carbohydrate
- generate energy anaerobically
- produce more blood cells
Answer: contract faster
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Q54. The sarcoplasmic reticulum in muscle cells acts as a: ---
- store of digestive enzymes
- store of sodium ions
- store of lipid
- store of calcium ions
- buffer of hydrogen ions
Answer: store of digestive enzymes
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Q55. Fast-twitch fibres contain: ---
- a relatively large number of mitochondria and low ATPase activity
- a relatively small number of mitochondria and low ATPase activity
- a relatively small number of mitochondria and high ATPase activity
- a relatively large number of mitochondria and high ATPase activity
- no mitochondria and high ATPase activity
Answer: a relatively large number of mitochondria and low ATPase activity
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Q56. Type I muscle fibres have the following characteristics ---
- white, glycolytic, slow contracting
- white, oxidative, slow contracting
- red, oxidative, fast contracting
- red, glycolytic, slow contracting
- red, oxidative, slow contracting
Answer: white, glycolytic, slow contracting
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Q57. For very high force contractions lasting 1-2 seconds, the initial energy source is from
- Glycolysis
- Creatine phosphorylation
- Phosphocreatine stores
- ATP stores
- None of the above --- Source: physiology/questions/mid sem 2018.pdf.
Answer: Glycolysis