Sensory receptors and the PNS Flashcards
what are the different kinds of somatosensory recepters ?
- Chemoreceptors detect chemical stimuli for smell taste and internal stimuli like blood pH and metabolite concentrations
- Photo receptors detect light stimuli from the retina
- Thermoreceptors detect temperature and temp changes
- Mechanoreceptors detect physical deformations in tissue (thought, changes in muscle length and tension, auditory and vestibular receptors and others)
- Noiciceptors in general detect pain, from mechanical sources, thermal stimuli
What kinds of things that we can’t sense ( and certain animals have them)
- Magnetorecepotrs detect earths magnetic field for navigation
- Infrared receptors detect heart in other organisms (snake)
- Electrorecpotrs detect electricity to help in navigation
what kinds of properties that receptors encode ?
Receptors encode stimuli nature, location, intensity and duration
What is the adaptation ? and what kinds of adaptation is in receptor and for what purpose ?
During the course of maintained stimulation, receptors begin to adapt and become less sensitive.
Some are slowly adapting (good for detecting static position)
Some are rapidly adapting (good for moving stimuli
What are the cell parts of sensory receptors ?
Receptive area (orange)
Mitochondrial area (always near receptive area to supply energy)
Synaptic area (into the CNS)
Transduction uses both ___________ and __________ potentials
Transduction uses both : Ionotropic (direct) like somatosensory, and others Metabotropic (2nd messenger systems e.g., olfactory, g-coupled proteins)
When receptor potential modulates the AP frequency the receptor potential is also know as a ___________
When receptor potential modulates the AP frequency the receptor potential is also know as a generator potential
Somatosensory recptors detect _______ , _______ or _______ changes
Somatosensory recptors detect mechanical, thermal or chemical changes
Somatosensory recptors have
cell body in a dorsal root or cranial nerve ganglion
An axon process that leads to spinal cord or brainstem
And “dendrite” process in the recepotor ending (e.g., skin)
Cutaneous Receptors : Our skin is covered with sensory endings, All are either __________ or __________ (whether a capsule covers the ending)
Cutaneous Receptors : Our skin is covered with sensory endings, All are either encapsulated or nonencapsulated (whether a capsule covers the ending)
What are the functions of Capsules ?
Capsules serve as filters of sensory information (as in rapidly adapting receptors) and as barriers for fluids (like myelin)
Noncapsulated recptors are either _________ or ____________ (but don’t surround the ending)
Noncapsulated recptors are either free nerve endings or endings with accessory structures (but don’t surround the ending)
Describe Endings around hair (encapsulated ? what kind of adapting ?)
Noncencapsulated** with accessory structures
Simple spiral ending
Responds to touch
Bending the hair deforms the sensory ending distorts the mechanically sensitive ion channels and leads to a generator potential
Hair receptors are rapidly adapting** because once bent, sensation ends
Describe Markel ending (where? encapsulation ? what kind of adaptation ?)
Nonencapsulated receptor endings with accessory structures found in both hairly and glabrous skin
Merkel cells on bottom of dermis (green)
Nerve terminal (blue) synapses onto several merkel cells and sends info about mechanical stimuli (usually pressure
Describe Meissner corpuscles. (where ? capsulation? adaptation? .. )
Found in glabrous skil (non hairy) elongated, encapsulated endings in the bottom of the epidermis, runs vertically
Corpuscles run zig-zag between layers of schwann cells (like a stack of pancakes) and respond to pressure/ tough to the skin (usually fingertips in humans)
Rapidly adapting receptors
More and more concentrations of receptors are move from palm to mid finger to fingertips
Describe Pacinian corpuscles (where ? adaptation ? … )
Encapsulated ending with distinctive onion layering (concentric layers of very thing epithelial cells and fluid)
Very widespread in body subcutaneous in location
The most rapidly adapting receptros of the body, they transmit quickly applied forced but do not transmit from sustained forces
Also transmit vibration very well
Descripe Ruffinin endings
Thin capsule ending that is cigar shaped and contains connective tissue (collogen)
Sensory fiber enters capsule and braches profusely
Slowly adapting
____________ are formed by branching terminations of sensory fibers in the skin (no encapsulation)
Free Nerve Endings are formed by branching terminations of sensory fibers in the skin (no encapsulation)
Only some form of _________ are free nerve endings
Only some form of mechaniorepectors are free nerve endings
Free nerve endings - more commonly are _______ and _______ and respond to pain itch and temperature
More commonly are nociorecepotrs and thermoreceptors and respond to pain itch and temperature
Some free nerve endings repond minimally in normal situations but become sensitive after tissue damage and inflammation called ____________
Some free nerve endings repond minimally in normal situations but become sensitive after tissue damage and inflammation called silent or sleeping noiceptros
What kinds of necireceptrs and how does mylination affect their function ?
Nociceptors axons are either myelinated or unmyelinated and are responsible for pain stages
Myelinated: fast pain sensation (delta pain)
Unmelinted axons tramit slower signal (slow pain)
What is hyperalgesia ? and allodynia?
Injured areas are increased pain levels - this is called (hyperalgesia)
allodynia swallowing hurts when you have a sore throat
Area around injury (burn) becomes red (flare) and swollen (edema) produced locally by an ________________ due to self healing mechanisms but restimulate same recepotrs bc AP go up toward skin
Area around injury (burn) becomes red (flare) and swollen (edema) produced locally by an azon relflex due to self healing mechanisms but restimulate same recepotrs bc AP go up toward skin
__________ = Long thin stretch receptors found in striated muscles long thing stretch
Muscle Spindles Long thin stretch receptors found in striated muscles long thing stretch
Simple structure with a few muscle fibers and capsule surrounding the middle third of the fibers
These fibers are intrafusal muscle fibers (inside the spindle)
The other 2/3 are extrafusal muscle (found outside spindle
Simple structure with a few muscle fibers and capsule surrounding the middle third of the fibers
These fibers are ___________ fibers (inside the spindle)
The other 2/3 are ___________ fibers (found outside spindle
What are the two types of intrafusal muscle fibers ?
Two types of intrafusal muscle fibers
Nuclear chain fibers (many cell nuclei that are lines up single file in chain)
Nuclear bag fibers (many cell nuclei arrangied many to a row)
what are the two types of sensory endings in muscle spindle ?
Primary endings (called annulospiral endings)
Secondary endings (also called flower-spray endings)
_________________ - One very large nerve fiber that enters the capsule and then branches off each branch wrap around on intrafusal fiber in a spinal pattern
Primary endings (called annulospiral endings) : One very large nerve fiber that enters the capsule and then branches off each branch wrap around on intrafusal fiber in a spinal pattern
________________ - A few small nerve fibers that branch off and innervate on either side of a primary ending
Secondary endings (also called flower-spray endings) - A few small nerve fibers that branch off and innervate on either side of a primary ending
Primary endings most sensitive to the ________________, while secondary endings are sensitive to the _______________
Primary endings most sensitive to the onset of a muscle stretch while secondary endings are sensitive to the maintenance of muscle stretch
Muscles spindles receive motor neurons. True or false ?
True
describe motoro innervation to muscle spindles :
Motor innervation to muscle spindles:
Alpha motor neurons large motor neurons that supply extrafusal muscle fibers
Gamma motor neurons for fusimotor neurons (smaller motor neurons that innervate those intrafusal fibers
Involved in feedback control of the muscle (at the receptor level) basically how sensitive muscle will be to stretch
Whereas muscle spindles detect ________ , golgi tendon organs detect _________
Whereas muscle spindles detect muscle length, golgi tendon organs detect muscle tension
____________ - Similar to ruffinin endings in that they have layers of collagen tand very thin capsule and branch out around the collagen in the muscle/ tendon
Golgi Tendon
Describe receptors in joints
Similar to those in skin and muscle
Free nerve endings
Ligaments have receptors similar to Golgi tendons organs
Joint capsules have receptors similar to ruffinin endings and few pacinian corpuscles
