Receptors Flashcards
What brain structure is required to perceive sensation?
- The cerebral cortex
How can afferent information control movement?
- Flexor reflexes
How does afferent information maintain arousal?
- Sensory information acts on the reticular formation to send stimuli to the cerebral cortex
What is a receptor?
Transducer that changes physical and chemical stimuli into electrical nerve impulses
What are the 4 receptor stimulus qualities?
- Modality
- Intensity
- Duration
- Location
What is modality?
- A labelled line code/ type of stimulus
i. e. vision, hearing, touch, taste, smell
What is intensity?
Frequency of stimulus
What is duration?
Relationship between stimulus intensity, and percieved intensity.
What is location?
The location of the receptor (Where it resides, and what type of discharges)
What 3 factors influence modalities and qualities of sensory receptors?
- Temporal and spatial patterns of activation
- Specificity of sensory endings
- Central connections (Where does the receptor project to in the CNS?; Brain has different areas for different types of signals)
What is meant by temporal activation?
How fast is the stimulus firing.
What is meant by spatial activation?
How many stimuli are present over the given tissue area.
What is meant by “labeled line”?
- Certain receptors primarily respond to a certain type of stimuli
What are the 5 major sensory modalities?
- Vision
- Hearing
- Smell
- Taste
- Somatic
What are examples of sub-modalities of vision?
- Color
- Motion
What are examples of submodalities of hearing?
- Pitch
What are examples of sub-modalities of smell?
The over 20 different types of odor
What are examples of sub-modalities of taste?
- Sweet, sour, salty, bitter, “umami”
What are examples of sub-modalities of somatic sense?
- Touch-pressure
- Warm-cold
- Flutter-vibration
- Pain
- Itch
- Tickle
- Position and movement senses
How is a higher amplitude stimulus interpreted by a sensory receptor? What is this called?
- A more intense stimulus leads to a higher rate of action potentials (all the same amplitude, but more frequent)
- Can be stimulated temporally or spatially
- Called rate coding
What is a topographic/ (somatotopic) map?
Specific areas of the brain correspond to specific areas on the body
What are the 3 anatomic classifications of sensory receptors?
- Exteroceptor
- Proprioceptor
- Interoceptor
Where are exteroceptors located?
- On external body surfaces in the cutaneous or subcutaneous tissue
Where are proprioceptors located?
- In tendons, joints, ligaments, and fascia/ deep tissue
Where are interoceptors located?
- On autonomic structures such as glands and organs
What qualities of sensation are received by exteroreceptors?
- Think of where they are located
- Touch
- Pressure
- Pain
- Temperature
- Smell
- Vision
- Hearing
What qualities of sensory input are received by proprioceptors?
- Position sense
- Movement sense
What qualities of sensory input are recieved by interoceptors?
- Digestion
- Excretion
- Circulation
- Respiration
- Taste
- Pain
- Visceral sensations
What are the 6 physiologic classifications of sensory receptors?
- Mechanoreceptors
- Thermoreceptors
- Photoreceptors
- Chemoreceptors
- Pain receptors
- Nociceptors
What are the 2 types of adaptation?
- Slow adaptation
- Fast adaptation
What is the novel stimulus of a mechanoreceptor?
- Physical or mechanical stimuli
What is the novel stimulus of a thermoreceptor?
- Temperature
What is the novel stimulus of a photoreceptor?
- Light
What is the novel stimulus of a nociceptor?
- Tissue damage
What is the difference between a fast and slow adapting receptor?
- A rapid adapting fiber quickly returns to a “base level”, and then spikes again when the stimulus is removed
- A slowly adapting fiber takes longer to return to base state of excitation, and doesn’t respond to a removal of stimulus
Which receptors are more for timing detection?
Fast adapting
Which receptors are more for spatial detection?
Slow adapting
Are large receptive field neurons found in areas of high or low sensitivity?
- Found in areas of low sensitivity
Are small receptive field neurons found in areas of high or low sensitivity?
- Areas of high sensitivity
Second order neurons create a larger receptive field using information from what?
- The convergence of several 1st order receptor neurons
How is 2 point discrimination explains using receptive fields?
Each point must be in a separate receptive field to be discriminated.
What does it mean if a receptor is encapsulated?
- It is covered in connective tissue
What are 2 types of non-encapsulated mechanoreceptors?
- Free nerve endings (for pain, thermo, and chemo)
- Hair follices (touch)
What is the name of the encapsulated mechanoreceptor for touch?
Meissner’s corpuscles
What is the name of the encapsulated mechanoreceptor for temperature/ cold?
Krause’s End Bulbs
What is the name of the encapsulated mechanoreceptor for kinesthetic sense/ pressure?
Ruffini End Organs
What is the name of the encapsulated mechanorecept for Touch and Vibration?
Pacinian Corpuscles
What is the name of the encapsulated mechanoreceptor for stretch?
Muscle spindle
What is the name of the encapsulated mechanoreceptor for tension?
Golgi Tendon Organ
Where are Ruffini Endings located?
Only within the glabrous dermis and subcutaneous tissue of humans.
What are Ruffini Endings particularly sensitive to, and what is their theorized main function?
- Sensitive to skin stretch, and though to contribute to kinesthetic sense and control of finger position and movement.
Are Ruffini Endings rapidly or slowly adapting mechanoreceptors?
Slowly
Do Ruffini Endings have large or small receptive fields?
Large
What are Meissner’s Corpuscles sensitive to?
Light touvh
Where are Meissner’s Corpuscles located?
- Just beneath the epidermi throughout the skin, but concentrated in fingertips, palms, soles, lips, tongue, face, and other areas that are especially sensitive to touch
Are Meissner’s Corpuscles rapdily or slowly adaptive mechanoreceptors?
Rapidly (Sensation is always changing)
Do Meissner’s Corpuscles have large or small receptive fields?
Small.
Why are Pacinian corpuscles the most studied receptor?
Because they are so large
What are Pacinian Corpuscles sensitive to?
- Deep pressure
- Touch
- High frequency vibration
What makes up the capsule of the Pacinian Corpuscles?
20 - 60 layers of concentric lamellae composed of fibrous connective tissue, fibroblasts, and separated by gelatinous material.
What are the lamellae of the Pacinian Corpuscles?
Very thin, flat, modified, Schwann Cells
Where are Pacinian Corpuscles found?
In deep subcutaneous tissue
Are Pacinian Corpuscles rapidly or slowly adapting mechanoreceptors?
Rapidly adapting
Do Pacinian Corpuscles have a large or small receptive field? What is special about its field?
Large receptive field with an especially sensitive center
How large is a Pacinian Corpuscle?
1 mm
What are Merkel Nerve Endings sensitive to?
- Touch
- PRESSURE and TEXTURE
Where are Merkel Nerve Endings located?
- In the superficial skin layers
- Clustered beneath ridges of fingertips that make up finger tips
What frequency vibration are Merkel Nerve endings especially sensitive to?
5 - 15 Hz
Are Merkel Nerve Endings rapidly or slowly adapting mechanoreceptors?
Slowly
Do Merkel Nerve Endings have large or small receptive fields?
Small
How many Merkel Nerve Endings may one affterent nerve fiber innervate?
Up to 90
What is the most abundant receptor?
Free nerve endings
Where are free nerve endings located?
In skin
- Penetrate epidermis and end in the stratum granulosum
Are free nerve endings rapidly or slow adapting mechanoreceptors?
Can be either, or intermediate
A5 are rapidly, and C are slowly
What are free nerve endings sensitive to?
- Temperature
- Mechanical stimuli
- Pain
Since free nerve endings are sensitive to different types of pain, what is it termed?
Polymodal
Are free nerve endings always encapsulated?
No.
