Referred pain results from the fact that cutaneous and visceral sensory pathways converge on the same spinal interneurons, so the brain cannot distinguish the original sources of pain from each other. Scotopic vision is characterized by high light sensitivity, which results from the fact that multiple rods converge on the same bipolar neurons and multiple bipolar neurons converge on the same ganglion cells, thus allowing for spatial summation in the rod pathways.
An insect crawling in one’s hair would trigger the hair receptors (peritrichial endings); the throb of a patient’s pulse is sensed by lamellated (pacinian) corpuscles in one’s fingertips; and reading braille stimulates tactile (Merkel) discs and tactile (Meissner) corpuscles.
The vitreous body presses the retina firmly against the choroid. Breakdown or reabsorption of this gel would allow the retina to detach from the choroid. This would not only result in areas of blurred vision, but removed from their blood supply, these regions of the retina would also die, producing irreversible blindness.
(a) Deafness; (b) dizziness and loss of equilibrium; (c) a hearing impairment with reduced ability to discriminate fine differences of pitch from each other; (d) increased risk of hearing damage from sudden loud noises, owing to the lack of the protective action of the stapedius muscle; (e) loss of proprioception from the hip, knee, and foot joints, and loss of cutaneous sensation from the gluteal region, genitals, and lower limbs.
Both olfactory and taste cells are chemoreceptor cells with apical processes (cilia and microvilli, respectively) that provide increased surface area for the binding of stimulant molecules. Both of them are directly exposed to the environment and have a rapid rate of death and replacement by the differentiation of stem cells. They differ in that olfactory cells are neurons, with a basal axon that projects to the brain, while taste cells are epithelial cells that synapse with a neuron at their base.
