Somatosensory Sensory Part 1 SN Flashcards
What is Sensory Information?
Neural activity originating from stimulation of receptor cells in specific parts of the body.
What did Aristotle define?
The 5 senses (Hearing, touch, smell, taste, vision) and the 6th sense (Intuition)
What is Somatic Sensation?
Conscious awareness - “perception”
Proprioception (position and movement of body parts)
Pain, Itch, Temperature
What is Visceral Sensations?
Homeostasis (conscious and unconscious) of the Organs, Heart, Lungs, etc.
What is Vestibular Sense?
Body stability and balance (position of the body in the gravitational field)
What do specific receptors respond to?
Specific stimuli (pain receptors vs thermal receptors)
What are Recursive Sensory Pathways?
Nervous System areas modify and structure incoming sensory information.
What is the Key Concept related to receptors?
Receptors function to transduce (action potentials) stimuli (bioelectrical, mechanical, chemical, thermal)
What are examples of sensory coding?
Touch, Balance, Pain, Proprioception (inside muscle tissue)
What is psychophysics?
Describes the relationship between physical characteristics of a stimulus and the attributes of the sensory experience
Who is Ernst Weber?
The founder of experimental psychology
What did Ernst Weber find?
The sensitivity of a sensory system to differences in intensity depends on the stimulus.
What was Ernst Weber’s Equation and what did each variable mean?
S = K x s
S - Just Noticeable Difference
K - Scaling Constant
S - Reference Stimulus
What was Gustav Fechner a founder of?
Psychophysics
What did Gustav Fechner find?
Described the relationship between stimulus strength (S) and the intensity of sensations (l)
What was Gustav Fechner’s Equation and what did each variable mean?
I = k x log(S/S0)
K = Scaling Constant
(S/S0) = Threshold of amplitude of a stimulus
What type of relationship did Ernst Weber’s equation have?
Linear Relationship
What did Stanley S Stevens examine?
Examined sensory response over a wide range of stimuli
The subjective experience of sensation (perception) described by a power function.
What was Stanley S Stevens equation and what does each variable mean?
I = k x (S - S0)n
I - Perceptual Intensity
K - Scaling Constant
S - S0 - Change in Stimulus Strength
N - Exponent “Shape of Function”
What is Sensory Threshold?
Lowest Stimulus strength that can be consciously detected
What is Magnitude Estimation?
Using a numerical estimate to rate the intensity of the sensory experience.
Exercise… rating or perceived exertion
Pain.. 0 - 10 scale
What is Magnitude Production?
Producing a stimulus strength based on the sensory experience (perception)
What is an example of magnitude perception?
Running at “50% of maximal effort”… does actually speed correspond to 50% of maximum speed
What is Neural Code?
The relationship between activity in a specified neural population and its functional consequences.
- Multiple stages of processing
What is an example of a neural code?
Muscle strength receptors.. reflex connection
What is a Receptor?
A cell that transforms stimulus energy into bioelectrical energy
What is Receptor Potential?
Refers to the amplitude and duration of a produced electrical signal.
What does receptor potential generate?
Action Potential Train
What is an Action Potential Train?
Series of Successive Action Potentials generated by 1 neuron.
What is an example of a sensory receptor?
Skin or muscle deformation
- Compression, stretch, vibration
- 6 different receptors in skin
- 3 different receptors in muscle.. sensitive to: muscle length; velocity of length change, force
What is Muscle Afferent?
Directed from organ to CNS
Where is a sensory neuron located?
In the cell body of the PNS (dorsal root ganglion)
What are dorsal root ganglion cells?
Pseudo-unipolar (bipolar)
2 axons (one originates in organ, other in CNS)
What is a Mechanical Stimulus on the skin?
- Scratch, indentation, force.
What is an Action Potential?
- Amplitude Decay
- Long Distance
What is the Proprioception?
Sense of oneself
Perception of body positions and movement.. produced by sensations of muscles, tendons, skins and joints
What is Exteroception?
Sense of direction interaction with the outside world
Sense of touch, contact, pressure.. identification or objects
Involves motor actions.. pressing, grasping, tapping.
What is Interoception?
Sense of internal state of the body
Active Muscle Contraction
Cardiovascular, respiration, digestion.. most not perceived
What is the process of detecting changes in the body?
Objects against the skin
Positions of Joints
Pain
What are the specialized nerves detecting stimuli?
Muscles, tendons, ligaments, skin, organs.
What is a Mechanical Stimuli?
Skin Stretch (physical contact)
What is a chemical stimuli?
Food
What are sensory receptors?
Specialized nerve endings that detect stimuli
Transmits action potentials via sensory axons
Afferent
What are most sensory receptors?
Mechanoreceptors - Sensitive to physical deformation
How do sensory receptors transmit information?
Ion channels
What are Mechanoreceptors?
Detects physical distortion of tissues (bending or stretching)
What are examples that would activate mechanoreceptors?
Knee movement, bladder distention, pinching skin.
What are Nociceptors?
Sensitive to potential damaging stimuli and for pain transmission
What are Thermoreceptors?
Sensitive to temperature changes
What are Chemoreceptors?
Sensitive to certain chemicals
What are Proprioceptors?
Sensitive to certain body positions and movement
What are the 4 stimuli?
1.) Modality
2.) Location
3.) Intensity
4.) Timing
What are the types of skin receptors?
Mechanoreceptors, nociceptors, thermoreceptors
What are fast adapting receptors?
Neuron discharge (action potentials) following exposure to a continued stimulus ceases (dies off)
What are Low Threshold Receptors?
Sensory receptors activated at low indentation forces, 0.5nM
What are High Threshold Receptors?
Activated at greater mechanical forces but mechanoreceptors activated for pain transmission
Where is the Pacinian Corpuscle located?
Lies deep in the dermis
What is the length and diameter of the Pacinian Corpuscle?
2mm long, 1mm diameter
What is the Pacinian Corpuscle made out of?
20-70 concentric layers of connective tissue.
What is the Pacinian Corpuscle?
Ending of a sensory nerve that acts as a receptor for pressure.
Why is the Pacinian Corpuscle a fast adapting mechanoreceptor?
Due to viscous fluid between concentric layers of connective tissue (low friction)
What is the Pacinian Corpuscle sensitive to?
High frequency stimuli (200 - 300 Hz)
What is Ruffini’s Ending (hairy and glamorous skin)?
Slow Adapting Receptor that detects skin stretch, joint activity and warmth.
What is Meissner’s Corpuscle (fingertips)?
A rapid adapting receptor responsible for transmitting sensations of discriminative touch and vibration
What is Merkel’s disk (epidermis)?
Sensory receptors in the epidermis that detect gentle touch and other tactile information
What is Krause End Bulbs?
Border of dry skin and mucous membrane lips that are sensory receptors in the human body that detect touch and respond to cold temperatures, pressure, stretching, and twisting
What is a hair follicle receptor?
“Modified” proprioceptor
What is a Receptive Field?
The region of sensory surface (skin) that when stimulated, changes the membrane potential of a neuron.
