sensory systems Flashcards
what are the general principles of sensory systems?
- each sensory organ has specialised sensory receptors
- each sensory system has a sensory pathway from receptors to the brain
across the sensoty system there are specialised sensoty receptor cells depending on the sensoty system
what is sensory transduction?
sensoty stimulus to neural impulses
what are sensory pathways?
there are multiple neurons that relay sensory signals to the sensoty cortex
what is sensory coding?
this is how neurons encode sensory signals by their electrical activity, which is their action potential
what is rate coding?
this means a certian feature of sensory stimulus (such as stimulus intensities) can be encoded by the rate or frequency of action potential
what is receptive field?
different neurons react in different ways to differentiate wavelengths of light
other sensory neurons also have receptive fields
what is topographic organisation?
- they are maps in the brain
as an entire collection of sensory neurons, you can find a ‘topographic organization’ in each sensoty area
what structural features do eyes have?
the retina- the most important structure of the eye, this contains photoreceptor cells
photoreceptor cells - rods (dim light) and cones (bright light and colour)
what is involved in phototransduction?
- ## rhodopsin (GPCRs and diferent types of rhodopsins detect different response spectra)
what are the stages in phototransduction?
photoreception triggers intracellular signalling to hyperpolarise photoreceptor cells
- after initial photoreceptor cells, neutral cells propagate throughout the retinal layers
- retinal ganglion cells are output cells which send signals to the second-order visual areas called the lateral geniculate nucleus in the thalamus
what is the visual pathway from retinal to visual cortex?
- retina
- optic nerve
- optic chiasm
- lateral geniculate body
- primary visual cortex
- left hand of the scene > processed by the right hemisphere of the brain
- right hand of the scene > processed by the left hand side of the brain
what is the hearing range?
what we can hear
what frequency of sound can dogs, humans and mice hear?
humans- 20Hz- 20,000Hz
dogs - 40Hz - 60,000Hz
mice- 1000Mz- 70,000Hz
what are average intensities of sound in:
- a very calm room
- a normal conversation
- hearing damage
- jet engine
- threshold of pain
- Very calm room: 20-30 dB SPL
- Normal conversation: 40-60 dB SPL
- Hearing damage: 85 dB SPL
- Jet engine: 110-140 dB SPL
- Threshold of pain: 130-140 dB SPL
what is amplitude in terms of the auditory system?
strangth of the wavelength
what is the sense of hearing acomplished by? and what are steps involved in it?
auditory transduction
- the ear concerts sound waves in the air into electrical impulses which can then be interpreted by the brain
- as sound eneters the ear, it travels down the ear canal and to the ear drum
-
what happens to the ear drum at different sounds?
- a lower pitch produces a slower vibration
- sounds of a higher pitch produces a faster vibration
- sounds of a lower volume produces a less dramatic vibration
the ear drum is cone shaped and articulates with a chain of bones known as the auditory ossicles, the malleis, the incus and the stapeduis
what happens after auditory transduction in the cochlea?
the auditory pathway the steps are: - cochlea - cochlear nucleus - superior olivary complex - inferior colliculus - medial genticulate body - auditory cortex
what is the auditory receptive field?
characteristic frequency which can emit sound-evoked responses at the minimum intensity
what is the tonotopic map?
toporaphic organisation in the auditory system is called ‘tonotopic map’ or ‘tonotopic organisation’
tonotopic organisation can be found not just in the cochlea, but also in the auditory cortex
what is the sensory organ for touch?
skin
what stomasensory receptors are involved wirth the skin?
- mechanoreceptors (the reaceptors for touch)
- thermoreceptors (the receptors for temperature)
- nociceptors (the receptors for pain)
what are the 2 afferent fibres for pain reception?
A-delta is myelinated, meaing it can send signals quickly
C-fibre is un-myelinated meaning that it sends signals slowly
what is the spinothalamic tract?
and what does it consist of?
its the pathway for nociception and thermoreception
it consists of:
1. dorsal root ganglia
2. spinal cord
3. ventral posterior nucleus of the thalamas
4. primary stomasensory cortex
what are the stages for the ‘dorsal column-medial meniscal pathway’
- dorsal root ganglia
- dorsal column nuclei
- ventral posterior neucleus (thalamas)
- primary stomasensory cortex
what is our topographic map called?
what parts of the body are over represented in the map?
stomatic map
the hands and face - this means that they are much more sensitive
what are the names of the sensory systems for smell and taste?
olfactorys system for smell
gustatory system for taste
where are the olfactory receptor cells?
theyre inside the nose, there is the nasal epithelium which contains olfactory receptor cells
what do the olfactory cells do?
they provide signals to the olfactory bulb, where mitral cells are output cells which send signals to the brain regions
why is the olfactory pathway unique compared to other sensoty pathways?
the mitral cells send their output to multiple brain regions
why is the olfactory pathway unique compared to other sensoty pathways?
the mitral cells send their output to multiple brain regions
what is the main area of the brain mitral cell outputs are sent?
the ‘prirform’ cortex which is an olfactory cortex.
the thalamus doesn’t directly contribute to olfactory processing
what do you know about the tounge?
thre are 5 modalities in taste reception
thier receptors are distributed across the tongue in a similar fashion
the tastebud is the structure of taste reception and it contains receptor cells with microvilli
what is the gastatory pathway?
- taste buds
- nucleus of the solitary tract
- ventroposterior medial nucleus
- insular cotrex
