Touch (Somatosensation) Flashcards
What are sensory receptors
Specialized receptors responsible for passing on the stimulus
-located in neural and non neural cells
How do non neural cells communicate with sensory neurons?
Non neural cells release neurotransmitters
what are the 4 sensory recepotrs
- Mechanoreceptor
- Chemoreceptors
- Thermoreceptors
- Photoreceptors
What is the sensory receptor threshold
the minimum stimulus required to activate sensory receptors
What is the definition of receptive field
The physical area in the sensory cell that relieves the stimulus
What is the sensory receptor for touch
Mechanoreceptor
- touch receptors
What are the 4 types of mechanoreceptors?
- Merkels Disks
- Ruffinis endings
- Meissners Corpuscle
- Pacinian Corpuscle
Which 2 mechanoreceptors adapt rapidly to stimulus
Meissner and Pacinian
Which 2 mechanoreceptors adapt slowly to stimulus
Merkels and Ruffini
How do mechanoreceptors differ?
- Receptive field
2. Adaptation rate
What are the 2 skin layers?
Epidermis
Dermis
What is the order of mechanoreceptors from closest to the epidermis to deepest
Merkels>Meissner>Ruffinis>Pacinian
Which mechanoreceptors have small receptive fields
Merkel and messier
Which mechanoreceptors have large receptive field?
Ruffini and Pacinian
What do thermoreceptors respond to
Specific temperatures and to changes in temperature
-Mainly interested in the change
Are there different thermoreceptors for hot and cold?
Yes
What is tactile acuity
Measured on the body surface by measuring 2 point discrimination
-the smallest separation between 2 points on the skin that is perceived as 2 points rather than one
What is the relationship between regions with tactile acuity and receptive fields
The higher the tactile acuity the smaller the receptive field
What is the somatosensory pathway to the brain?
Mechanoreceptors>Dorsal root>Spinal Segment>Spinal Cord> Thalamus>Somato Sensory Cortex
Where is the somatosensory cortex located
Postcentral gyrus, Areas 3,1,2
Where is the primary motor cortex located
Located on the precentral gyrus
How is the body represented in somatosensory cotex
Represented with a somatotopy
-certain regions are over and under represented
What is the relationship between cortical neurons and receptive fields
Cortical neurons are smallest on your fingers and become larger as you go up the hand and forearm
What are the 3 ways in which the plasticity of the somatosensory system changes
- Changes cortical maps caused by increasing or decreasing stimulation
- Plasticity from amputation
- Plasticity following training
What is pain
Unpleasant sensory and emotional experience associated with actual or potential tissue damage
How is the sensation of pain received
Nociceptors
What is the definition of Nociception
The sensory process that provides the signals that trigger pain
What is the definition of Hyperalgesia
An increased sensitivity to painful stimuli
What is the definition of Analgesia
Inability to sense pain
Can the brain feel pain
No, the brain can’t feel itself and doesn’t have any pain receptors
