6.1 General Senses Flashcards
3 Physiologic types of tactile sensation
Mechanoreceptive
Thermoreceptive
Nociceptive
T/F In general senses, there is a specific, specialized organ or structure for detecting stimuli
False- NO Specific organ
3 classifications of tactile sensation based on location
Exteroreceptive
Proprioceptive
Deep
What classifications of tactile sensation based on location is from body surface
Exteroreceptive
Define proprioceptive
Position senses
Pressure senses from feet
Equilibrium
Classification of tactile senses based on information carried
- Pain and temperature
2. Fine discriminatory touch
Stimulation of receptors in skin or tissue directly beneath the skin
Touch
Tactile sensation where there is deformation of the skin
Pressure
Tactile sensation where there is rapid repetitive signal
Vibration
T/F Touch, pressure, vibration are detected by the same type of receptors
True
Tactile receptor that is widely distributed and detects touch and pressure
Free nerve endings
Free nerve ending : touch and pressure
________________ : vibration and deep pressure
Pacinian corpuscle
Specialized mechanoreceptors sensitive to movement of objects over skin
Meissner’s corpuscle
Meissner’s corpuscle : encapsulated by dendrites
Pacinian corpuscle : _______________
encapsulated by lamellae
Sensation for Ruffini’s endings
Continuous deformation
Describe adaption of different tactile receptors
Hair-end organ- rapidly adapting Meissner's corpuscle- fast adapting Pacinian corpuscle- rapidly adapting Merkel's disc- slow adapting (initially strong then adapting weaker signal) Ruffini's endings- slow adapting
2 types of summation
- Spatial summation
2. Temporal summation
Summation wherein increasing signal strength is transmitted by using progressively greater number of fibers
Spatial summation
Increase in stimulus -> __(1)__ nerve fibers stimulated -> ___(2)___ sensation felt
- More
2. Stronger
Summation wherein increasing the frequency of nerve impulses in each fiber will increase signal intensity
Temporal summation
As the impulse increases -> ______ signal is felt
Stronger
Note: as impulses are sent more rapidly, the strength of the stimulus is perceived to be higher
Spatial : stimulus
Temporal : _______
Impulse
Accumulation of neurons
Neuronal pool
Stimuli below the threshold for excitation
Subthreshold stimuli
Stimuli above the threshold required for excitation
Suprathreshold stimuli
The stimulation is over but the signal persists
Afterdischarge
Note: rhythmical signals like breathing
Classify according to adaptation response and receptive field:
MEISSNER
F1 (fast adapting type 1)
Classify according to adaptation response and receptive field:
PACINIAN
F2 (fast adapting type 2)
Classify according to adaptation response and receptive field:
MERKEL
S1 (slow adapting type 1)
Classify according to adaptation response and receptive field:
RUFFINI
S2 (slow adapting type 2)
T/F receptors are clustered at certain points
True
Condition for area to be highly sensitive
Dense innervation + small receptive field
General sensory pathway
Receptor -> first order neuron -> spinal cord/brain stem -> second order neuron -> thalamus -> third order neuron -> cortex
2 sensory pathway
- Dorsal column-medial lemniscal pathway
2. Anterolateral system/ spinothalamic tract
DCML : medulla
_________ : spinal cord
Anterolater/ Spinothalamic tract
Brodmann’s area for somatosensory cortex
Brodmann’s area 1-3
Brodmann’s area for somatosensory association areas
Brodmann’s area 5,7
Loss of ability to recognize complex objects felt on one side
Amorphosynthesis
Ability to discern that 2 objects touching the skin are truly 2 distinct points
Two-point discrimination
At high levels of stimulation it becomes harder to detect changes in stimulus strength
Weber-Fechner Principle
In vibration sense, up to _____cycles/sec can be detected
700
Specific cutaneous region supplied by a given dorsal root ganglion
Dermatome
Pain receptors are ________
Free nerve endings
Agent most responsible for causing pain following tissue damage
Bradykinin
