Sensory Receptors Flashcards
What is known as the process where sensory receptors receive information from both the internal and external environment and encode the information for transmission to various area of the nervous system?
Sensation
What is known as the process where the CNS receives and interprets the sensations based on present experiences, the present state of the internal and external environment, and memory of similar situations?
Perception
What type of perception occurs at the cortical level?
conscious perception
What type of perception occurs at the cerebellum level?
unconscious perception
The basal ganglia is involved in what type of perceptions?
the basal ganglia is involved in unconscious representations of movement experiences, but also involved with perceptions of inter- and intrapersonal space
What is known as changing the energy of a stimulus into a neural energy?
sensory transduction
The stimulus energy causes what to change in the receptor membrane during sensory transduction?
The stimulus energy (mechanical, chemical, light) produces a change in the receptor membrane (aka local potential difference). Na+, K+, and Cl- channels open to allow ion movement. This potential change is local and spreads only a few mm as it decays.
What is known as the amount of stimulus energy it takes to cause a local receptor potential?
Threshold for stimulation
True or false: Threshold for stimulation depends on the physical properties of the receptor?
True
What is known as the lowest stimulus intensity necessary for perception of stimulus?
Threshold of perception
– usually the same as receptor threshold, but may be modified by context and experience
What is known as the duration for which the receptor potential is generated to the stimulus?
Adaptation
True or False: Adaptation of a receptor is NOT determined by the morphology of the receptor?
FALSE - Speed of adaptation is determined by the morphology of the receptor
What type of adapting receptors end signaling before stimulus is removed and tell when the stimulus was applied?
Rapidly adapting receptors
What type of adapting receptors continue signaling for the duration of the stimulus and tells us how long the stimulus lasted?
Slowly adapting receptors
– action potentials are repeated through length of the stimulus duration
What type of sensory information coding refers to the receptors being specialized by their morphology to respond to only one type of stimulus?
Specificity Coding (Quality)
The intensity of a stimulus is directly related to the ______ of the receptor potential and the _______ of receptors activated.
size; number
The intensity of a stimulus is transferred to the generation of an AP and coded by what two things?
the frequency of AP and the number of discharge fibers
The _______ the stimulus, the _______ the size of the receptor potentials (depolarization), the ______ the number of receptors being activated, the ________ summation of the depolarizing events and thus the ________ frequency of APs.
stronger greater greater greater increased
Only the _________ of APs is changing, NOT the _______ of the _______ with which the APs are traveling.
frequency
amplitude
speed
What is known as the area surrounding the receptor that when stimulated excites or inhibits the firing of a particular cell?
Receptive field
What parts of the body have the smallest receptive fields and the largest number of receptive fields per area, making them the most sensitive parts of the body?
tips of the fingers and the tongue
As you move proximally, receptive field size ______ and density of receptors _______, as does the sensitivity.
Increase; decrease
What is known as the area of the body surface contributing sensory input to one dorsal root?
Dermatomes
What is known as excitatory discharge being greatest at the center of the receptive field and inhibitory at the periphery?
lateral inhibition
– serves to enhance distinction between two stimuli and aids in recognition of pattern and contour
The areas with the _______ receptor density will have the _______ cortical receptive fields.
largest; largest
What type of receptors are stimulated by the external environment?
Exteroreceptors
What type of receptors are stimulated by position of body segments relative to each other and position of body and head in space?
Proprioceptors
What type of receptors signal body events such as blood glucose level and blood pressure?
Interoceptors
Sensory receptors are classified by what three categories?
1) stimulus location
2) sensory system
3) stimulus energy
What are the 6 categories of the sensory system classification?
1) somatic - tactile, joint, muscle, tendon, thermal, pain
2) visual
3) vestibular
4) auditory
5) olfactory
6) gustatory
What type of receptors responds to touch/pressure, proprioception, and air waves?
Mechanoreceptors
What type of receptor responds to taste, smell, blood gas level?
Chemoreceptors
What type of receptor responds to damaging stimuli (pain)?
Nociceptors
What type of receptor responds to heat and cold?
Thermoreceptors
What type of receptor responds to light?
Photoreceptors
What type of sensory fibers have large diameter axons with increased levels of myelin?
Encapsulated fibers: Ia, Ib, II
What type of sensory fibers have small diameter axons with decreased to no myelin?
Non-encapsulated fibers: III, IV
What sensory fibers have a large axon diameter (12-20 micrometers), a fast conduction velocity (70-120 m/s) and innervate primary afferent receptors of the muscle spindle?
Ia (A- alpha)
What sensory fibers have a larger axon diameter (12-20), a fast conduction velocity (70-120 m/s), and innervate receptors of Golgi tendon organs?
Ib (A - alpha)
What sensory fibers have a moderate axon diameter (5-14), a moderate conduction velocity (30-70 m/s), and innervate secondary afferent receptors of the muscle spindle, touch, pressure, and vibration?
II (A - beta)
What sensory fibers have a small axon diameter (2-7), a slow conduction velocity (12-30 m/s), and innervate receptors of touch, pressure, pain, and temperature?
III
What sensory fibers have a small axon diameter (0.5-1), a slow conduction velocity (0.5-2 m/s), and innervate receptors of pain and temperature and unmyelinated fibers?
IV (C)
Small diameter fibers have a _______ conduction velocity. Why?
Slower; because they provide more resistance to flow of current and have less insulation from myelin
Small diameter fibers have ______ amplitude. Why?
Lower; because potential change across the membrane is smaller.
Small diameter fibers have a _______ threshold for stimulation. Why?
Higher: because they offer more resistance to current flow (example: C fibers will require higher intensity of stimulation to activate)
Which motor neuron innervates extrafusal muscle fibers?
Alpha (A-alpha)
Which motor neuron innervates intrfusal muscle fibers?
Gamma (A-gamma)
Which motor fibers have the fastest conduction velocity?
Alpha (A-alpha)
Which motor fibers are lightly myelinated?
preganglionic ANS fibers (B)
Which motor fibers are unmyelinated?
postganglionic ANS fibers (C)
What are the 4 types of cutaneous mechanoreceptors?
1) Meissner’s Corpuscles
2) Pacinian Corpuscles
3) Merkel’s disks
4) Ruffini’s Corpuscles
What nerve fiber type innervates all four cutaneous mechanoreceptors?
Type II (A-beta)
Are cutaneous mechanoreceptors considered high or low threshold?
low-threshold (high sensitivity)
Which cutaneous mechanoreceptor type lies between the dermal papillae just beneath the epidermis, are rapidly adapting and transduces information about the relatively low-frequency vibrations (30–50 Hz) that occur when textured objects are moved across the skin?
Meissner’s Corpuscles
Which cutaneous mechanoreceptor type lie in the subcutaneous layer, are rapidly adapting and provide information primarily about the dynamic qualities of mechanical stimuli?
Pacinian Corpuscles
Which cutaneous mechanoreceptors are slowly adapting?
Merkel disks and Ruffini’s Corpuscles
Which cutaneous mechanoreceptors are rapidly adapting?
Meissner’s Corpuscles and Pacinian Corpuscles
Which cutaneous mechanoreceptor type is located in the epidermis, where they are precisely aligned with the papillae that lie beneath the dermal ridges, and play a major role in the static discrimination of shapes, edges, and rough textures?
Merkel’s disks
Which cutaneous mechanoreceptor type is located deep in the skin, as well as in ligaments and tendons, are particularly sensitive to the cutaneous stretching produced by digit or limb movements, and respond primarily to internally generated stimuli?
Ruffini’s Corpuscles
Where are Type I (encapsulated Ruffini-like) joint mechanoreceptors located?
ligaments, joint capsule, and proximal joints