Topic 45 Receptor and effector endings – structure and functions
Covers the two main types of nerve endings, receptor and effector. Receptors are split into unencapsulated free terminals, such as Merkel cells, free endings and root hair plexuses, and encapsulated corpuscles, including Meissner, Pacinian, Krause and Ruffini types. Effector endings are described through the myoneural junction's structure and the autonomic endings by transmitter. The note then classifies receptors by sensory modality, location and morphology.
Inside: 5 sections · 14 flashcards · 2 min
Topic 45 of 59 in the MU Pleven syllabus for Cytology (Medicine, Year 1). The free AceMed note covers it in 5 sections, about 324 words (2 min of reading), with 14 flashcards.
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Topic 45 Receptor and effector endings – structure and functions
Nerve endings are of two types:
Receptor nerve endings
Effector nerve endings
Receptors can be classified according to:
Nerve endings are of two types:
1. Receptors
2. Effectors
Receptor nerve endings
Receptors are structures that transduce stimuli into signals in sensory nerves. They can be divided into 2 types, depending on if they have CT capsule or not:
Unencapsulated (free) nerve terminals
Encapsulated nerve terminal – covered by CT capsules of various structures
Touch and pressure is detected by both encapsulated and free nerve endings
Unencapsulated
Most widely distributed; abundant in skin, mucous and serous membranes, muscle, deep fascia, viscera walls
Includes:
Merkel cells – associated with nerve endings; respond to light touch
Free nerve endings – respond to temperature and pain; also function as tactile receptors
Root hair plexuses – located in hair follicles of reticular dermis; detect hair movements
Encapsulated
All phasic mechanoreceptors, responding rapidly to stimuli on the skin
Four types in human skin:
Meissner corpuscle – fingertips, palms, soles
Pacinian corpuscle – respond to touch and pressure
Krause end bulbs – skin of the penis; respond to pressure
Ruffini corpuscles – respond to pressure
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