Concept explainers
Concept introduction: The sensory receptors are the nerves which are stimulated by a physical stimulus and create nerve impulse to send information to the brain. The tactile receptors are the most numerous types of sensory receptors. These receptors are present in the skin and mucous membranes. The dendritic nerve endings of tactile receptors are either unencapsulated or encapsulated.
Answer to Problem 1DYB
Correct answer: Unencapsulated dendritic endings of sensory neurons are called free nerve endings.
Therefore, option b. is correct.
Explanation of Solution
Reason for the correct answer:
Option b. is given as “free nerve endings”.
The free nerve endings are the apex of any tactile sensory receptor and are not covered by any protective layer on their end. These receptors are found closest to the skin surface and mucus membrane. The free nerve endings are sensitive to pain and temperature stimuli.
Hence, option b. is correct.
Reasons for incorrect answers:
Option a. is given as “lamellated corpuscles”.
The lamellated corpuscles are covered by the connective tissue and specialized glial cells. They are located at the reticular layer of the dermis, soles of the feet, breasts, and the external ganglia as well as walls of the some organs. Hence, option a. is incorrect.
Option c. is given as “bulbous corpuscles”.
These nerve endings are also known as ruffini endings. These receptors are found in cutaneous tissues. These are spindle shaped neurons and have a covering layer. Hence, option c. is incorrect.
Option d. is given as “end bulbs”.
These are rounded or oval structures located at the dermis, mucous membranes of the nasal cavity, oral cavity, vagina, and the anal canal. These receptors are covered by the connective tissue and specialized glial cells. Hence, option d. is incorrect.
Hence, options a., c., and d. are incorrect.
Free nerve endings are the receptors that are unencapsulated.
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