W6 - Sensory Input Flashcards
Why are the 5 classic senses not well considered in physiology?
Some of these senses measure the same or multiple different stimuli (e.g. touch - pressure, temp and damage and hearing + taste - both chemical stimuli)
What is the definition of signal transduction?
The conversion of environmental factors into neural information (APs)
What are the 5 modalities?
Mechanoreception, thermoreception, photoreception, chemoreception and nociception
What are the 5 types of mechanoreception?
Pressure, body positioning, sound, acceleration and gravity
What does thermoreceptors detect? (e.g. sensors in HT, free nerve endings in skin)
Temperature
What do photoreceptors detect? (e.g. rod and cone cells)
Electromagnetic waves
What do chemoreceptors detect? (e.g. olfactory/gustatory receptors)
Specific chemicals
What does nociception detect? (NK1 receptors for substance P)
Cellular damage
Describe the two ways neurons are stimulated?
Directly - stimulus depolarises afferent neuron directly, Indirect - sensory cell (e.g. epithelial cell) is stimulated to release NTMs that stimulate the afferent neuron
What do pacinian corpuscles detect?
Vibration
Pressure in the form of high frequency waves deform the lamella and the dendrite, how does this cause depolarisation?
Opens stretch mediated Na+ channels
What 2 things do muscle spindles respond to and tell the brain of?
Muscle length and rate of change of length
Are pacinian corpuscles and muscle spindles directly or indirectly stimulated?
Directly
Hair cells are modified epithelial cells that help in hearing, what is the kinocilium and what does this link to?
Kinocilium - tallest cilium, links to stereocilium
When the kinocilium bends away/towards the stereocilia what happens?
Away from - K+ channels open, Towards - K+ channels closed
What is it that causes the movement of kinocilia?
Sound waves vibrate the tectorial membrane that causes them to bend
There’s canals of extracellular gel that help to detect acceleration + gravity, what do the heavy otoliths do to detect gravity when the head tilts or acceleration as you move?
Pulls gel down or sideways, bending the hair cells’ kinocilium
WHen muscle spindles shorten, does the AP frequency increase or decrease?
Decrease
What is the example of neurons being indirectly stimulated?
Hearing using modified epithelial cells (hair cells)
Are different receptors for touch all detecting the same thing?
No, the receptors are sensitive to only one modality
Stimulus location says that…
A sensor should be able to determine the location of the stimulus
What happens to the APs as the stimulus intensity increses?
APs get more frequent as you recruit more receptors
Tonic receptors are ???? adapting receptors that respond for the ??????????????????
Slowly, duration of the stimulus
Phasic receptors are ???? adapting receptors, how do they fire APs during a constant stimulus?
Quickly, they fire once at the beginning of the stimulus and then switch off, then fire again when the stimulus ends
In the somatosensory system, areas of the brain are uniquely attributed to………..
Certain body areas (e.g. homunculus)
