The Somatosensory System Flashcards
What is somatosensation?
Somatosensation is sensory category that includes all sensation received from the skin and mucous membranes.
What are the three layers of skin?
Epidermis, dermis, and the subcutaneous layer
What is the epidermis?
The epidermis is the very top layer of skin which is a thin barrier to water and diseases.
What is the dermis?
Below the epidermis is a thicker layer (the dermis) which contains blood vessels, sweat glands, hair follicles, and other important glands and structures.
What is the subcutaneous layer?
the deepest layer of your skin. It’s made up mostly of fat cells and connective tissue. The majority of your body fat is stored here. The subcutaneous layer acts as a layer of insulation to protect your internal organs and muscles from shock and changes in temperature.
What do these neurons require?
They require many types of receptors to convert many types of sensory input.
What are encapsulated mechanoreceptors?
They are special sensory receptors that respond to touch, pressure, and vibration. They respond to mechanical stimuli.
What are the four major types of encapsulated mechanoreceptors?
Meissner’s corpuscles, Ruffini’s corpuscles, Pacinian corpuscles, and Merkel’s disks.
What do all four types of mechanoreceptors have?
They all have long thickly myelinated axons that help information get to the brain quickly. However, some temperature and pain information doesn’t have this as it is not as critical for survival.
What are pacinian corpuscles?
Located in the subcutaneous layer of the skin, they detect deep vibrations and pressure.
When the stimulus is applied, the corpuscle deforms and the fluid is smooshed. Once the stimulus is gone, the corpuscles fluid redistributes–reshaping it.
What are Meissner’s corpuscles?
Located in the dermis, these corpuscles are smaller than the pacinian and can be found in hairless places.
They convert low frequency vibrations or little flutters.
What are Ruffini’s corpuscles (endings)?
Located in the dermis, they can be found on both hairy and hairless skin and they detect skin stretch and tangential force.
What are Merkel’s disks?
Located in the dermis, they can be found on hairy and hairless skin and convert light touch. They perceive light touch, shape, and texture.
What is the difference between Pacinian and Meissner’s corpuscles vs. Ruffini’s endings and Merkel’s disks?
Pacinian and Meissner’s corpuscles both have a rapid adapting property while Ruffini’s endings and Merkel’s disks don’t adapt rapidly. They fire action potentials for the entire duration of the touch stimulus.
What are touch receptive fields?
Each mechanoreceptor responds to a touch stimulus in a specific area of the skin, a region called the receptive field of the receptor. When the receptive field is touched, the mechanoreceptor will be activated.
What is two-point discrimination?
This is a measure of how close two nearby objects that are both touching the skin can be to one another before your skin cannot tell that they are truly two distinct points.
What are dermatomes?
A dermatome is all the skin innervated by one level or segment of spinal cord.
What must all receptors do?
They all have to send their axons with info to the brain except for the ones in the face and neck which use cranial nerves.
How are the thirty spinal segments divided up?
There are thirty spinal segments which are divided into four major groups named based on that specific part of the vertebrae. There are eight cervical spine segments, twelve thoracic spine segments, five lumbar and five sacral.
