Lecture for Ch 10.1: Sensory Receptors Flashcards
What stimuli types can stimulate nocireceptors?
heat, cold, pressure, chemicals, pH
What NTs are responsible for pain reception?
substance P and glutamate
What can reduce pain (chemical NT class)?
endogenous opioids: endorphins, enkephalins, dynorphins
If the optic nerve delivers an impulse, the brain interprets it as ______ even though the impulse is _________ for hearing
light; the same as
Receptors classes: by information delivered
1) proprioreceptors (body position and fine muscle control)
2) cutaneous (skin, touch, texture, pressure, temperature, pain)
3) special senses (vision, hearing, taste, smell, eq)
Receptor classes: by origin of information
1) exteroreceptors - respond to stim outside of body
2) interoreceptors - respond to stim inside (blood pressure, ph, [O2], etc.)
Receptor classes: by how they respond
1) phasic (adapting)
2) tonic (maintained response)
Phasic Receptor Properties
- respond to burst of activity when stim first applied but quickly adapt by decreasing response
- may deliver another short burst when stim removed
- alert us to changes in env.
- sensory adaptation to reduced attention to constant stim
- examples - touch, smell, temp.
Example of tonic receptor
nocireceptors
Why do we perceive a punch n the eye as a flash of light?
because nerve fibers can only send information about experience as their assigned sensory modality: optic nerve fibers that are stimulated can only send signals that are perceived as light
Why does paradoxical cold exist?
because nerve fibers can only send information about experience as their assigned sensory modality; if cold receptors are stimulated, whether or not it is cold, they will send a signal of cold to the brain
EPSPs in receptors are known as ….
generator potentials
What is the function of the “onion skin” of pacinian corpuscles?
As a phasic receptor, the pacinian corpuscles have layers that help to grade/diminish the generator potential response to pressure
How do generator potentials work in tonic receptors
the generator potential is proportional to the intensity of the stimulus; increase intensity results in increased freq of AP after threshold is reached
Which cutaneous receptors are naked?
pain, cold, heat
merkel’s disks
sense indentation; close to skin surface
meissner’s corpuscle
changes in texture; close to skin surface
pacinian corpuscle
deep pressure; deep in skin
ruffini endings
skin stretch; deep in skin
root hair plexus
light bruising; around hair follicle
Do we have more cold receptors or more hot receptors?
cold
Cold receptors are ______ by warm
inhibited
What temp range do cold receptors respond to?
8-28 degrees C
Cold receptors serve as an ion channel for _____ and are therefore also known as ____
sodium and calcium; a Transient Receptor Potential (TRP) channel
Are warm receptors located more proximal or deep to skin than cold receptors?
deeper
Warm receptors are ______ hot receptors
different from
Hot receptors are also known as
capsaicin receptors; nocireceptors; TRP channels
When are hot receptors activated?
≥ 43 degrees C or in response to chili pepper eating
Myelinated nocireceptors produce
sudden sharp pain
Unmyelinated nocireceptors produce
dull, persistent pain
What causes acute itch?
Histamine release from mast cells and basophils
What causes chronic itch?
stimulated by other chemicals and does not respond to antihistamines
What do itch receptors stimulate?
unmyelinated sensory axons to the spinal cord
the ____ receptors, the _____ the receptive field, the ________ the area in the _______ cortex
more; smaller; larger; somatosensory
small receptor fields lead to _____ sensation = ______ acuity
sharper; tactile
