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level: Level 1

Questions and Answers List

level questions: Level 1

QuestionAnswer
when are endorphins released?inescapable pain sex, thrilling music decreases depressed mood
What is the hierarchical organisation of the sensory system?1. association cortex 2. secondary sensory cortex 3. primary sensory cortex 4. thalamic nuclei 5. receptors
explain the levels of hierarchyeach level of sensory hierarchy receive input from lower levels with increasing level neurons respond to stimuli of greater specificity
what is sensory organisation?hierarchical organisation also reflected in differentiation sensation & perception
what does sensation mean?process of detecting presence of stimulius
what does perception mean?higher order process of integrating recognising & interpreting sensations
describe what the pupil doeslight enters eye through pupil size of pupil regulated by iris high illumination= small pupil
what is the retina?contains receptors & 4 other types of neurons neurons arranged in layers, receptor cells on innermost layer
axons in the retinal ganglion cell..leave the eye in a bundle bundle- optic nerve = gap in receptor layer= blind spot blind spot filled by visual system from surrounding receptors
what is the fovea?area in centre of retina specialised for high vision
what are rods?periphery of retina respond best to faint light outnumber cones (20x) many rods converge to 1 ganglion cell
what are cones?fovea, also surround fovea respond to bright light needed for colour vision each cone associated with one ganglion cell
what is a photopigment?when struck by light, release energy activates 2nd messengers inhibit activity of receptor cell initiates signal transduction across other neurons
what is the retina geniculate striate pathway?90% of axons of ganglion cells signals from left visual field reach right visual cortex & vice versa
retina to primary visual cortexlight from left visual field meets right retina axons from nasal part of retinas cross (optic chiasm) axons from temporal part of retinas don't cross after optic chiasm signals go through thalamus to primary visual cortex
what is the summarised pathway of light?eye > retina > brain
what is optic chiasm?axons from nasal part of the retinas cross
what is edge perception?contrast perception
why do we need to move our eyes?3 brief eye movements per saccades high acuity, coloured perception needed to maintain retinal images neurons in visual system respond to change not steady input
how does colour vision work?mixture of wavelengths of light that it reflects wavelengths between 400- 700nm 2 principles- component & opponent processing
what is component processing?3 different types of cones photopigment in each cone= responsive to short/ medium/ long wavelengths perceived colour depends on relative activity of 3 cones
what is opponent processing?neurons respond in opposite direction to commentary colours at all levels of visual pathway NOT reactors explains why complementary colour cannot exist together
what is colour blindness?can't distinguish certain colours results from deficiency/ absence of photopigments often red/ green deficiencies mainly men
what is the primary visual cortex?1st stage of visual processing receives input from thalamus
what is the secondary & association visual cortex?each composed of different areas areas specialised for particular types of visual analysis (colour etc.) interconnecting pathways major streams in visual stream: dorsal & ventral system
what is the dorsal stream?primary visual cortex > dorsal peristriate cortex > posterior parietal cortex 'where' stream- primarily involved in perception of where thing are damage- possible to describe object can't reach out & grab object
what is the ventral system?primary visual cortex > ventral prestriate cortex > inferotemporal cortex 'what' stream- involved in perception of what things are
what are a group active neurons called?an assembly
what do receptors do?receptors with different characteristics perception of range of different touch & pain sensations sensory pathways
sensory pathway 1touch & position of body axons ascend on same side of body, cross over to other side of brain stem pathway continues to thalamus neurons project to primary somatosensory cortex (SI)
sensory pathway 2pain & temperature neurons cross over to contralateral side when enter spine part of pathway continues to thalamus other part terminates in brain stem neurons that reach thalamus project to (SI, SII)
what is the SI postcentral gyrus?somatotopy organised according to map of body surface input from contralateral output to secondary somatosensory (SII) & association cortex
what is the secondary somatosensory cortex?input from same side & opposite side SI output to association cortex
what is the association cortex?posterior parietal lobes input from SI & secondary somatosensory areas extensive damage to right posterior parietal lobe= asomatognosia
how do we feel pain?mild pain- glutamate strong pain- glutamate & substance P
2 pathways of pain to the brainthalamus= somatosensory cortex pathway- conveys sensory aspects of pain limbic system= prefrontal cortex pathway- reacts to emotion associated with pain
what happens in pain relief?morphine bind to opiate receptors in CNS opiate receptors block release of substance P= reduced pain body produces own opiates- endorphins endorphins inhibit release of substance P in spine gate control theory