Sensory Receptors MCQs

Since touch receptors are distributed sparsely on some body areas, such as backs, knees and elbows, the distance needed to discriminate between two tiny point sources of touch may be large Reference: Ganong, 25th edition page no.161

Free nerve endings are located in the mesentery of the gut Reference: Ganong, 25th edition page no.172

Slowly adapting receptors These types of receptors fire in response to a stimulus initially but if the stimulus is maintained, they continue firing but their frequency is decreased Examples are Merkel cells, Ruffini corpuscles, Pain receptors, Muscle spindles, joint capsule receptors Reference: Ganong, 25 th edition page no.161

Single neuron receives 500 inputs from 150 different sensory cells and refers to convergence. Convergence means signals from multiple inputs uniting to excite a single neuron. Convergence can result from multiple input fibers from a single source. Convergence can also result from input signals (excitatory or inhibitory) from multiple sources. Convergence is one of the important means whereby the central nervous system correlates, summates, and sorts different types of information.

Pacinian corpuscle respond to deep pressure and high frequency fast vibration Reference: Ganong, 25th edition page no.160

Ruffini endings Seen around joint capsules They respond to sustained pressure They are very sensitive to skin stretch Reference: Ganong, 25 th edition page no.160

Presynaptic facilitation - produced when the action potential is prolonged and the Ca² + channels are open for a longer period Reference: Ganong, 25 th edition page no.123