Adequate stimulus in a sensory system refers to: The molecular processes whereby
ID: 80298 • Letter: A
Question
Adequate stimulus in a sensory system refers to: The molecular processes whereby a sensory receptor cells converts the energy in a stimulus into a biochemical signal or change in membrane potential. The usual and appropriate stimulus that produces a physiological response in a particular receptor (e.g. photons of a certain wavelength, changes in air pressure, a chemical with certain properties, heat energy, etc.). A property of sensory systems whereby activation of a receptor cell is perceived in a particular way (i.e. as a flash of light) regardless of how the cell is actually activated All of the above Which of the following statements is/are TRUE? Most somatosensory neurons in skin form their first synapse in the ventral horn of the spinal cord. Cell bodies of most primary somatosensory neurons are located in the dorsal root ganglia. Thermal stimuli in skin are transduced by TRPC channels in free nerve endings. Ability to detect textures on a surface requires tonic mechanoreceptor cells in skin. All of the above are true The activity of which of the following proteins is inhibited during vertebrate phototransduction cascades in rods and cones? Rhodopsin Transducin (G_T) cGMP-gated channels cGMP phosphodiesterase none of the aboveExplanation / Answer
Answer 5) The correct answer is option (b).
The molecular processes whereby a sensory receptor cell converts the energy in a stimulus into a biochemical signal or change in membrane potential are termed as sensory transduction.
A property of sensory systems where activation of the receptor cell is perceived in a particular way regardless of how the cell is actually activated is termed as univariance. The sensory neurons, their receptors, and neuronal circuits do not have information what stimulated them and they give the same type of response regardless.
Answer 6) The correct answer is option (b).
Phasic mechanoreceptors have the ability to detect textures on the surface whereas tonic receptors are useful in sensing temperature and proprioception.
Nerve endings are composed of keratinocytes which are responsible for sensing the physical and chemical stimulations.
Answer 7) The correct answer is option (c).
In the phototransduction cascade, the absorption of a photon by an inactive rhodopsin cause conformational changes that result in the activation of rhodopsin which in turn activates the heterotrimeric G protein transducin. G protein catalyzes the exchange of GDP for GTP. The complex dissociates into active T*-GTP and T, and rhodopsin activates many other transducin molecules.In the next step, G*-GTP bind to the inhibitory subunits of cGMP phosphodiesterase, thereby releasing the inhibition on the catalytic and subunits, which in turn catalyzes the hydrolysis of cGMP. The decrease in the cytoplasmic free cGMP concentration causes the closure/inhibition of cGMP-gated channels on the plasma membrane. This leads to the blockage of the influx of cations due to which circulating dark current get reduced.
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