PSYC2274 Chapter Notes - Chapter 13: Dorsal Root Ganglion, Lamellar Corpuscle, Bulbous Corpuscle
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Name and describe the 3 layers of skin:
- Epidermis is the outermost layer. This is also the thinnest! It has a layer of dead skin cells
at the top and then a layer of living cells.
- Dermis is the middle layer. This contains blood vessels, hair follicles, and nerve endings.
- Hypodermis is the last layer, and it anchors the skin to muscles and other tissues.
What are mechanoreceptors?
- These are neurons that transduce tactile stimulation, and they are located in the outermost
layers of the skin. They also respond to some kind of movement in the skin and can be
differentiated from each other in 3 different ways: size of the receptive field, types of skin
movement that causes a response, and whether they are FA or SA.
What are the 4 types of mechanoreceptors?
- Pacinian corpuscle responds to high frequency vibrations (50-700 Hz). this is good for
detecting initial contact with an object and responds to abrupt, rapid movements of the
skin.
- Meissner’s corpuscle responds to low frequency vibrations (5-50 Hz) and is fast adapting,
so it is good for detecting dynamic stimuli, or motion of an object across the skin. They
have small receptive fields, which aids in detecting motion across the skin.
- Merkel’s discs (cell neurite complexes) respond to steady downward pressure and are
good for the careful inspection of surfaces.
- Ruffini endings respond to stretch and are slow adapting, so they are good to detect
grasping.
What is the dorsal root ganglia?
- This is located right outside of the spinal cord and is where the cell bodies of
mechanoreceptors are located.
What are dermatomes?
- These are literally “skin slices” and are where input from the skin to the central nervous
system are organized. They are bands of body surface innervated by cells of a single
dorsal root ganglia pair. These dermatomes overlap only slightly.
What is proprioception?
- This is a body sense that tells us where our limbs are in space. Can also be called
kinesthetic.
- Proprioception is mediated by muscle spindles, which respond to uncommanded muscle
lengthening and can tell us the position of our limbs relative to our expectation based on
motor output.
What is touch?
- Touch refers to the sensations caused by the mechanical displacement of the skin. This
occurs any time you make contact with an object. Tactile, the adjective of touch, refers to
these mechanical interactions.
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Document Summary
Name and describe the 3 layers of skin: It has a layer of dead skin cells at the top and then a layer of living cells. This contains blood vessels, hair follicles, and nerve endings. Hypodermis is the last layer, and it anchors the skin to muscles and other tissues. These are neurons that transduce tactile stimulation, and they are located in the outermost layers of the skin. Pacinian corpuscle responds to high frequency vibrations (50-700 hz). this is good for detecting initial contact with an object and responds to abrupt, rapid movements of the skin. Meissner"s corpuscle responds to low frequency vibrations (5-50 hz) and is fast adapting, so it is good for detecting dynamic stimuli, or motion of an object across the skin. They have small receptive fields, which aids in detecting motion across the skin. Merkel"s discs (cell neurite complexes) respond to steady downward pressure and are good for the careful inspection of surfaces.
