General Sensory info Flashcards
How are paramecium sensitive to touch and temperature?
Mechanosensitive VC Ca2+ channels.
Paramecia perform chemotaxis, how?
- Hyperpolarization - attractant
- Depolarization - repellant
What are the general sensory principles?
- Detection of external stimulus
- sensory cells are transducers
- Signal sent to the NS
- (Reception, transduction, transmission, perception)
Descrive sensory receptor cells.
- Cells specialized for detecting a signal
- found in a complex sense organ (ex. eyes, nose)
- or isolated cells embedded in nonsensory cells (ex. touch sensitive cells in skin)
A generator potential occurs in a ________ and a receptor potential occurs in a _________.
Sensory neuron, epithelial sensory receptor cell.
Describe the characteristics of a sensory receptor protein.
- detect incoming signals
- specialized proteins
- conformation change
- ionotropic/metabotropic
What are the 6 categories of physciological sensory receptors?
- chemoreceptors
- mechano
- photo
- thermo
- electro
- magneto
What is the difference between a adequate and polymodal stimulus?
- adequate - most receptors have a preferred stimulus modality (ex. photoreceptors and light)
- polymodal - receptors respond to a number of stimuli (ex. nociceptors or ampullae of lorenzini)
What are the 4 different kinds of information encoded in a sensory stimulus?
- modality
- location
- intensity
- density
What is the labelled line hypothesis?
(Modality) >> There is a discrete pathway from the sensory cell to the integrating area. Ex. can stimulate “hearing” in deaf people by stimulating the auditory nerve at different frequencies.
The receptive field (stimulus location) is determined by…
- field size
- receptor density
How does lateral inhibition improve acuity?
Dynamic range of a neuron is inversley proportional to…
the ability to discriminate
Neurons that encode intensity logarithmically are less likely to…
respond to smaller changes in stimulation.
Where does the integration of thermal information happen?
Hypothalamus
Mammals have three (and possibly another) types of peripheral sensory receptors, what are they?
- warm
- cold
- painfully hot
- painfully cold
Define warm receptors.
- sensitive starting at +30oC in mammals
- increasing frequency as temperature increases
Define cold receptors.
- sensitive to small changes in T (0.5oC)
- respond to T change rather than absolute value
When do nocireceptors fire in response to painful heat?
>45oC, increasing frecuency as temperature and pain increases
What are TRPs?
- Transient receptor potential - proteins that allow thermal receptors to detect temperature.
- non-selectively permeable to cations
- regulate membrane depolarization
- large family found in vertebrates and invertabtrates
- commonly invovled in sense reception
What are pit organs (snakes)?
Able to sense IR heat, PO floor is lined wiht heat-sensitive neurons. IR warms the floor and activates TrpA channels
How do magnetobacteria align with magnetic fields?
Megnetite
What is magneto-perception?
Sensitivity to magnetic fields
What is the free radical theory of magnetosensitivity?
Madnetic fields influence the free-radical state of molecules.
