PHYS: Sensory Systems Flashcards
1
Q
3 steps of a sensory pathway
A
- translation: stimulus detected by receptor
- transduction into neural impulse
- transmission of AP to brain
2
Q
2 types of senses
A
- somatic: provide sensory info from external environment (inc. exteroception, proprioception)
- visceral: sensory info from internal organs e.g. pain, discomfort (inc. interoception)
3
Q
how does transduction into a neural signal occur
A
- stimulus causes opening of ion channels which further alters receptor’s RMP > graded (receptor) potential
- a second type of channel (one which is sensitive to the stimulus e.g. light) opens > ions flow in and threshold is reached > AP
4
Q
3 types of sensory systems
A
- type 1: receptor = extension of the neuron itself e.g. somatosensory, proprioception, olfaction
- type 2: receptor = separate cell e.g. auditory, taste, vestibular
- type 3: intermediate cell between the receptor and sensory nerve (only vision)
5
Q
how to code for increased sensory AP firing (5 ways)
A
- open up more ion channels on the receptor = increased chance of reaching threshold
- increase intensity of stimulus = activates sensory neurons w/ higher thresholds
- temporal summation (quicker repetition) of stimuli > more APs
- fluctuant stimulus leads to more frequent APs than a constant stimulus
- vary location of the stimulus so that the brain perceives it as diff signals
6
Q
4 types of excitatory circuits
A
- converging: allows multiple pieces of information to be consolidated into one output e.g. sensory info from diff parts of the body contributes to one experience
- diverging: one signal disperses into several diff outputs e.g. many muscles contract
- reverberating: neurons fire in a loop, useful for establishing a rhythmic pattern e.g. breathing
- parallel: one neuron to many parallel circuits and then back to one
7
Q
2 types of inhibitory circuits
A
- feedforward: prevents the neuron further down the chain from firing e.g. relaxing an antagonist muscle for movement
- feedback: allows response to happen and then turns off signal (useful for rhythmic patterns e.g. breathing)
8
Q
synthesia
A
- mixing of sensory inputs e.g. seeing sounds/hearing colours
- may be due to increased cross-wiring b/n brain regions for vision and hearing
9
Q
what is a neuronal pool?
A
- groups of neurons that process info from various sources and forward it to other destinations
- contain both excitatory and inhibitory neurons
10
Q
proximal vs distal stimuli
A
- proximal: energy that directly stimulates your receptors (e.g. light/sound waves)
- distal: the object within the environment (e.g. camera flash which creates a light wave)
11
Q
features of a receptor cell
A
- less polarised compared to neuron
- voltage gated channels are leaky
- responds to mechanical and chemical stimuli
- have receptor potentials (GP) which can lead to an AP if large enough
12
Q
spiny vs non-spiny neurons
A
- spiny: release glutamate (usually excitatory)
- non-spiny: release GABA (usually inhibitory)
13
Q
2 types of zones in a neuronal pool
A
- discharge zone: receives increased % of AP
- facilitated zone: receives decreased % of AP
14
Q
2 types of processing
A
- serial: one neuron to the next
- parallel: one input results in many outputs
15
Q
3 types of synapses
A
- axo-somatic: synapse onto body of neuron (inhibitory)
- axo-dendritic: synapse onto dendrite of neuron (usually excitatory)
- axo-axonic: synapse onto axons (synapse regulation)
16
Q
white vs grey matter in the brain
A
- white: inside - mainly conducting info
- grey: outside - mainly processing info
17
Q
do fatter or thinner neurons transmit signals faster?
A
- fatter - less resistance
18
Q
are sensory or motor fibres faster?
A
- sensory b/c more myelinated
19
Q
differences b/n APs and GPs
A
- APs use voltage gated channels whereas GPs use chemical/mechanical gated channels
- APs are shorter lived than GPs
- GPs are bidirectional, APs are unidirectional
- GPs decrease with distance, APs do not
- APs are all or nothing whereas GPs increase w/ stimulus size
- APs have a refractory period, GPs do not
