Term
| Somatic afferent fibers (two types) |
|
Definition
| Exteroreceptive (skin and specialized sense organs - eyes ears) Proprioceptive (muscles joints tendons, etc - positioning organs) |
|
|
Term
|
Definition
| Unique stimulis that activates a sensory receptor at low energy level. |
|
|
Term
|
Definition
| Tuning of receptor to a specific stimulus energy (photoreceptors to a certain range of wavelengths). |
|
|
Term
|
Definition
| Sensory receptors optimally selective for a single type of stimulis energy. A particular type of sensation will be perceived (even getting punched in the eye produces light). |
|
|
Term
|
Definition
| Receptor Speceficity and line of communication underlie. Sensory information travels along a prescribed path to the CNS where information is interpretaed. |
|
|
Term
| What are the biological transducers? |
|
Definition
|
|
Term
| Process of converting stimulis energy into electrical energy |
|
Definition
|
|
Term
| Activation of a receptor generates what type of potential? |
|
Definition
| Receptor potentials. Na+ and Ca+. These are electrotonic and are PASSIVELY propagated. If stimulis is large enough, an AP will be triggered. |
|
|
Term
| Action potentials differ from an electrotonic potential that decays with distance in the axon by: |
|
Definition
1. Activated in all or none fashion
2. actively propagated along axons
3. have uniform amplitude |
|
|
Term
| Intensity of a stimulis in the dorsal horn is encoded by? |
|
Definition
| The frequency of the firing of APs. (APs are all the same height, so intensity of a stimulis is based on the frequency of dorsal horn sensing of APs). So receptor potential increases to make an AP (so frequency and amp matter), but only freq matters for AP sensory in the dorsal horn. |
|
|
Term
|
Definition
| Relationship of stimulis intensity and AP frequency. |
|
|
Term
| How is Stimulis Threshold different from Adequate Stimulis? |
|
Definition
| Stimulis threshold is a measure of the sensitivity of an individual receptor - some may need a higher stimulis energy. Adequate stimulis is just the stimulis with the lowest energy. |
|
|
Term
|
Definition
| Recruitment of additional high-threshold receptors with increased stimulis intensity. e.g. large stimulation activating sensory receptors on adjacent neurons. |
|
|
Term
|
Definition
| Area in peripheral space where a stimulis activates a sensory receptor. |
|
|
Term
| T/F Sensory receptors can only respond to an adequate stimulis presented within its receptive field |
|
Definition
|
|
Term
| T/F Receptors with large receptive field maps reduce resolution of the somatotopic map |
|
Definition
|
|
Term
| Areas of high tactile discrimination have: |
|
Definition
| high densities of receptors with small receptive fields. |
|
|
Term
|
Definition
| Sensitivity of a receptor and action potential firing rate decreases despite continued stimulation. |
|
|
Term
| Exception to adaptation rule |
|
Definition
| those receptors that respond to noxious (painful) stimuli. Nociceptors do not adapt and when there is inflammation may become more sensitive. |
|
|
Term
Tonic Receptors
What do they let you know? |
|
Definition
| Slowly adapt or remain active during an applied stimulis. - DURATION |
|
|
Term
Phasic Receptors
What do they let you know? |
|
Definition
Only change during application/cessation of a stimulis. Good at signaling the beginning and end of a stimulis, but not duration.
Some pick up on rate at which a stimulis is applied (measure acceleration of a stimulis). |
|
|
Term
| What are the sensory systems? |
|
Definition
| Somatosensory, Visual, Auditory, Vestibular, Olfactory, Gustatory, and Nociception. |
|
|
Term
| Modality of a sensation is determined by |
|
Definition
| The type of receptors that are activated. |
|
|
Term
| What are the four modalities of somatic sensation? |
|
Definition
| Touch (size, shape, texture), Proprioception (static and movement of limbs/body), Nociception, Thermal |
|
|
Term
| Somatosensory system receives sensory input from: |
|
Definition
| epidermis, muscles, joinsts, internal organs, and the CV system. |
|
|
Term
|
Definition
| Epidermal sensory receptors which are surrounded by layers of tissue that act as filters to modify the mechanical stimuli. e.g. rapid adaptation of somatosensory receptors. |
|
|
Term
| Non-encapsulated receptors |
|
Definition
| Free nerve endings (nociceptors) or nerve endings associated with or surrounded by accessory sensory structures (Merkel endings, hair receptors). |
|
|
Term
|
Definition
| Free nerve endings, hair receptors, merkel disc receptors, meissner corpuscle, pacinian corpuscle, ruffini endings |
|
|
Term
| Free nerve endings (location, sensitive to?) |
|
Definition
| Located in the epidermal layer and respond to tissue-damaging mechanical and thermal stimulation. |
|
|
Term
|
Definition
| Movement of hair - generally rapidly addapting and respond to movement but not steady pressure. |
|
|
Term
|
Definition
| Located in the basal layer of the epidermis. Disc is formed by two structures - the Merkel cell and its associated sensory nerve ending. Single sensory fiber supplies several Merkel cells. These SLOWLY adapting mechanoreceptors - mainly TACTILE. |
|
|
Term
|
Definition
| ENCAPSULATED nerve ending located in dermal layer of the glabrous (hairless) skin. RAPIDLY adapting mechanoreceptors. Abundant in fingertips for FINE TACTILE sensation. |
|
|
Term
|
Definition
| RAPIDLY-ADAPTING ENCAPSULATED MECHANORECEPTOR located in the subcutaneous layer of skin. Responds to changes in stimulis. Poor sensors of maintained pressure but are the FASTEST RAPIDLY ADAPTING FIBERS and are good at detecting things like vibration. |
|
|
Term
|
Definition
| Slowly-Adapting mechanoreceptor located in the dermis and subcutaneous layers. The nerve ending is encapsulated within layers of collagen. |
|
|
Term
| What are the more superficial mechanoreceptors? |
|
Definition
Merkel (slow tactile) -basal epidermis
and Meissner (rapid fine tactile) - dermal layer |
|
|
Term
| What are the deeper mechanoreceptors? |
|
Definition
Pacinian corpuscle (rapid pressure/vibration) - subcataneous
and Ruffiniendings (slow pressure - maintained pressure) - dermis and subcutaneous |
|
|
Term
| Sensory Receptors Involved in Proprioception |
|
Definition
Vestivular Receptors (ear orientation), Muscle Spindle (skeletal muscle with annulospiral endings Ia intrafusal and stretch receptor 1a extrafusal - position speed direction). Golgi Tendon Organ (located in the tendon near insertion of muscle), Joint Receptors (Ruffini and Pacinian), Stretch Receptors of Skin (Signal postural info Ruffini Merkel, hair receptors)
. |
|
|
Term
|
Definition
| Free nerve endings widely dispersed in epidermal layers of skin and viscera. Noxious/tissue damaging mechanical, thermal, and chemical. |
|
|
Term
What are the most rapidly conducting nocicepter afferents?
Thermal temp range? |
|
Definition
Adelta. Mediate sharp initial pain. Umyelinated C fibers may respond to mechanical, thermal, chemical, etc. Dull sensation. In general all are slowly adapting to maintain response to stimulis.
<10 and >45 centigrade |
|
|
Term
|
Definition
| Respond to multiple types of noxious stimuli - pinch, puncture, heat, cold, and irritating chemicals. Largest class. |
|
|
Term
|
Definition
Chemicals released from damage tissue increase the sensitivity of the nociceptors to noxious stimuli (aspirin reduces prostaglandin by inhibiting cyclooxygenase).
Neurons respond to tissue distribution of: histamine, serotonin, acetylcholine, prostaglandin, potassium ions, and ATP. |
|
|
Term
| Substance P and Calcitonin Gene Related Peptide CGRP |
|
Definition
| Act on blood vessels to increase local blood flow and on Mast cells to promote the release of histamine both of which promote inflammation. NEUROGENIC INFLAMMATION. |
|
|
