Ch16 (16.2)-General Senses (Sensory Receptors)

What are free nerve endings? What do they do? Where are they located?

(simplest tactile receptors) They are tactile receptors that detect temperature and pain stimuli. They are located closest to the surface of the skin (preferably near the papillary layer) May be phasic or tonic (meaning it can either take long to adapt or fast)

How does the dendritic endings of sensory receptors (tactile receptors) look like?

Dendritic endings are either unencapsulated or encapsulated.

What are the most numerous type of sensory receptors? Which includes?

Tactile receptors are the most numerous type of sensory receptors that includes mechanoreceptors (in skin) and mucous membranes.

How are general sense receptors organized?

They are organized into somatic sensory receptors- includes tactile receptors (un-encapsulated and encapsulated) of the skin and visceral sensory receptors)

what are encapsulated tactile receptors? which includes?

encapsulated tactile receptors are neuron endings wrapped by connective tissue or either covered by Glial cells called neurolemmocytes includes end bulbs lamellated corpuscles Bulbous corpuscles Tactile corpuscles

What are tactile discs? What do they do? Where are they located?

flattened endings of sensory neurons (similar to merkel cells-tactile cells) found in basal layer of epidermis respond to light touch

What are unencapsulated sensory receptors? Which includes?

unencapsulated sensory receptors are terminal endings of sensory receptors with no protective covering Free nerve endings Root hair plexuses tactile discs

What are end bulbs ? What do they do? Where are they located?

wrapped in connective tissue located in the dermis and mucus membranes of oral cavity, nasal cavity, vagina, and anal canal detect deep pressure and low-frequency vibration Tonic receptors (take long to adapt)

What are bulbous corpuscles?

wrapped in connective tissue located within dermis and hypodermis detect continuous deep pressure and skin distortion Tonic receptor (slow to adapt)

What are tactile corpuscles? What do they do? Where are they located?

wrapped in neurolemmocytes and connective tissue located in sensitive regions of the body (lips, palms, eyelids, nipples, and genitals) allow recognition of texture/shape and detect light touch Phasic receptors (fast to adapt)

What are lamellated corpuscles? What do they do? Where are they located?

wrapped in neurolemmocytes and connective tissue located in the dermis, hypodermis, and some organ walls of palm of hands, soles of feet, breasts, and external genitalia detect deep pressure, course touch and high frequency vibration Phasic receptors (fast to adapt)

What are root hair plexuses? What do they do? Where are they located?

wraps around hair follicle located in deeper layer of dermis (recticular layer) detect hair displacement Phasic receptors (fast to adapt)