Intro to Senses Flashcards
Define transducer.
How many stimuli can it respond to?
Where are they located?
transducers are specialized receptor cells. They reside in sensory receptor organs such as the cochlea and only respond to one stimulus.
Transduction
The translation of info in the environment into a signal the brain can understand
Explain doctrine of specific nerve energies.
Who proposed this?
States that receptors and neural channels for different senses are independent. Stated that only one sensation is produced and that each uses different nerve energies.
Labeled Lines. Explain this BITCH.
Labeled lines is the current concept that includes action potentials traveling from sensory receptors along different nerve tracts to the brain. The different “lines” allow for perceptual differences. Also, neurons are specialized for each sense.
nociceptor
May not respond to one type of energy.
Rather, responds to magnitude of energy large enough to cause tissue damage. Related to sensation of pain.
What do bare nerve endings respond to?
Pain, temp
What type of receptors have encapsulated endings?
Mechanoreceptors such as pacinian and meissners
Name some specialized cells
olfactory, rod, cone, vestibular, auditory, taste
Describe transduction through generator potentials.
Generator potentials are are the graded, decementally spread, slow, local depolarizations that eventually lead to action potential if threshold is reached.
synonym for generator potential
receptor potential
Give the order of transduction from incoming energy to action potential
stimulus > generator potential > action potential
i.e. vibration causes deformation of pacinian corpuscle > generator potentials occur as mechanically gate ion channels open > threshold reached > action potential
contrast sensory experience vs action potential
action potentials are all or nothing, but sensory experiences are not. Frequency of action potentials is proportional to generator potential amplitude and therefore stimulus intensity
What is the purpose of receptive fields
to allow precise localization of stimulus. Cells can be selective to react to small or large stimuli by the size of their threshold
facts about receptive fields
All sense have receptive fields
the smaller the receptive field, the more precise the info sent to brain
Some receptive fields are excitatory in the middle and inhibitory surround. or vice versa. This allows for detection of lines\discontinuities
Tactile corpuscle: synonym and what does it respond to
meissners corpuscle, responds to light touch. its phasic
name for tonic tactile corpuscles
merkle’s
What do free nerve endings respond to
pain and temp
Lamellated corpuscle. name and stimulus
Pacinian, vibration
What does the ruffini corpuscle respond to
deep pressure
Need to look at:
homunculus, innervation of pacinian corpuscle, peripheral mediation of pain, major classes of somatic sensory receptors
Describe large myelinated axons
Fast transmission and mechanosensation
describe samll myelinated axons
moderate speed
pain, temp, mechanosensation
describe unmyelinated axons
slow
pain, temp, crude mechanosensation, visceral
adaption
receptors tend to slow discharge with time when stimulus doesnt change. Even though the stimulus is constant, the generator potential decreases and action potential frequency decreases as a result=
