Special senses Flashcards
What does transduce mean?
(=change) environmental info changed into APs – the common language of NS
Each type of receptor responds to a particular ______. (define term)
modality (=form of info, e.g. sound, light, pressure)
_____ receptors respond at a constant rate as long as stimulus is applied. Example ______
Tonic
Pain
_____ receptors respond with a burst of activity but quickly reduce firing rate at constant stimulation (______). Example ____ and _____
Phasic
Adaptation
Smell and touch
__________ sense chemical stimuli.
Chemoreceptors
What receptor responds to chemicals in external environment?
Exteroceptors
What receptor responds to chemicals in the internal environment?
Interoceptors
What receptor transduces light?
Photoreceptors
What receptor responds to temp. change?
Thermoreceptors
What receptor responds to deformation of their cell membrane?
Mechanoreceptors
What receptor responds to intense stimuli by signaling pain?
Nociceptors
What receptor signals positional info of body parts?
Proprioceptors
What receptor are near an epithelial surface and respond to touch, pressure, temp, or pain
Cutaneous Receptors
What receptors are part of a sensory organ and respond to hearing, equilibrium, sight, taste, and smell?
Special sense receptors
What is the sensation that is produced by a receptors normal stimulus?
Adequate stimulus
Mechanism in Mechanoreceptors?
Deformity detected via sensory dendrites or deform hair cells
Mechanism in Pain receptors?
Damaged tissues release chemicals that excite sensory endings
Mechanism in Chemoreceptors?
Chemical interaction affects ionic permeability of sensory cells
Mechanism in Photoreceptors?
Photochemical reaction affects ionic permeability of receptor cell
What are generator potentials?
Sensory receptor equivalent of Excitatory postsynaptic potential that is produced in response to adequate stimulus.
Generator potentials are proportional to ?
Stimulus intensity
AP frequency is proportional to _____ of generator potential.
Amplitude
In phasic receptors the generator potential _____ to a constant stimulus and quickly _____ in amplitude
Adapts
diminishes
In tonic receptors, generator potential ____ ___ adapt to a constant stimulus
does not
Cutaneous receptors such as pain and temp are mediated by ___ and ___ encapsulated nerve endings. They are _____ receptors. ( tonic vs phasic)
free and encapsulated
tonic
_____ ____ and ____ _____ are slow adapting, expanded free nerve endings that mediate touch
Ruffini endings
Merkel’s discs
Encapsulated nerve endings mediate touch and pressure (Anterior spinothalamic tract) . They are able to ____ quickly and include what two structures?
adapt
Messiner’s and pacinian corpuscles
Cold receptors are located in the ____ ___, while warm receptors are located _____ in ____.
upper dermis
deeper in dermis
What neurotransmitters are used by nociceptors?
Glutamate and Substance P ( aka Pain NT)
Heat elicits pain thru _____ receptors.
Capsaicin
Sensations from cutaneous and proprioceptors Carried by ? and then in ?
large, myelinated nerve fibers in dorsal columns of spinal cord
medial lemniscus to thalamus and sensory cortex (postcentral gyrus)
A receptive field is a ?
area of skin whose stimulation results in changes in firing rate of sensory neuron.
Pattern of receptive fields?
Larger field = less sensory receptors and vice versa
Two-Point Touch Threshold
Is minimum distance at which 2 points of touch can be perceived as separate
Two-Point Touch Threshold is a measure of ____ ____ or distance between receptive fields
tactile acuity
Lateral Inhibition is ?
- CNS process that sharpens sensation
- Sensory neurons at center of stimulation area inhibit more lateral neurons
What are the four papillae and where are they located on the tongue?
Vallate- back of tongue Fungiform- tip and sides Foliate- sides
Filiform- tip and anterior 2/3
Explain the function of taste.
Receptors on hairs detect dissolved substances
What are the 5 taste types?
Sour Salty Bitter Sweet Umami
What chemical is responsible for the umami taste?
Glutamate (MSG)
_____ ___ are modified epithelial cells with microvilli that detect taste. Each on consists of ___ - ___ modified epithelial cells.
taste buds
50 - 100
Which taste types don not have receptors and instead act by passing thru channels?
Salty and sour
Explain the process of salty taste causing a sensory neuron stimulus.
- sodium passes through channel into taste bud and cause depolarization.
- Calcium channels are opened
- Neurotransmitter is released causing stimulus.
Explain the process of sour taste causing a sensory neuron stimulus
- H+ pass through ion channel and other routes to cause depolarization.
- Calium channels open.
- NT is released which causes stimulus
Explain the process of sweet and umami taste causing a sensory neuron stimulus
- sugars and amino acids bind with membrane receptor
- G proteins cause release of secondary messenger
- K channels close
- Depolarization
- NT released.
Explain the process of bitter causing a sensory neuron stimulus
- Quinine bind with membrane receptor
- G proteins cause release of secondary messenger
- K channels close
- Depolarization
- NT released.
What three cranial nerves are involved with taste?
Trigeminal nerve ( CN 5 / lingual branch) ( anterior portion) Glossopharyngeal nerve ( CN 9 and middle portion) Facial nerve ( CN 7 and posterior portion)
Explain the neuronal pathway of taste from cranial nerves 5/7/9 to brain.
- CN 5/7/9 relay stimulus to Nucleus of tractus solitaries
2. Information is relayed from nucleus of tractus solitaries to thalamus, and from thalamus to taste are of cortex.
The olfactory apparatus consists of ?
receptor cells
supporting cells
basal cells
What is the olfactory hairs?
Cilia which lies in mucous
Receptor cells are bipolar neurons that send axons to _____ ______. (smell)
olfactory bulb
____ ___ are stem cells that produce new receptor every 1 -2 months.
Basal cells
Supporting cells contain?
detoxifying enzymes
Gives the basic process of smell from odors.
- odorants bind to chemoreceptor molecules and act through G proteins
- This causes depolarization that leads to initiate action potentials in neurons.
What is responsible for extreme sensitivity of smell ? ( humans nose can detect a billionth of ounce of perfume in air.
The high number of G proteins associated with single receptor. ( up to 50)
Explain the neuronal pathway of olfaction.
- Fibers of olfactory nerve receive stimulus
2. information is relayed from olfactory bulb to Medial , lateral, and intermediate olfactory area.
