Human sensation part 1
- Created by: Emily-Jade99
- Created on: 02-01-18 21:51
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- Human sensation
- Senses are needed for survival (e.g. locating food/knowing territories)
- Sensation - Detection of simple properties of objects reaching our sensory system (e.g. colour/shape)
- Perception - To make sense of these properties, to recognise objects, their location, their movement and their backgrounds
- E.g. hearing is a voice sensation, but recognising the voice is perception
- Sound - Change in pressure, producing vibration
- Vibrations reach the eardrum and are transmitted to a set of 3 little bones (Ossicles)
- Inner ear
- Ossicles transmit the vibration to a fluid-filled structure inside the inner ear called Cochlea
- Vibrations then transmit to the Oval window
- Basilar membrane vibrates in response to pressure at oval window created by bones of the middle ear
- Vibration causes displacement of cochlea fluid and movement of 'hair cells' on surface of basilar membrane (hair cells = auditory response)
- Transduction - Process by which 'physical' energy or stimulation is converted into neutral information
- Auditory receptor organ is called 'Organ of Corti'/spiral organ
- Auditory
- High frequencies cause ONLY the end of the basilar membrane near the middle ear to vibrate
- Low frequencies cause vibrations along a greater distance of the basilar membrane
- Axons in auditory nerves fire at different times (brain can detect difference in firing rate of a fraction of a millisecond)
- Volume is coded by the amplitude of vibration of the basilar membrane
- Sensory coding
- Reception - Receptor neurons absorb physical energy
- Transduction -Physical energy is converted into electrochemical energy represented by the firing pattern of different neurons
- Coding - Receptors are specialised to absorb and transduce 1 kind of energy
- The physical and chemical properties of food molecules determine the taste sensation
- Taste signals travel along a neural pathway from the tongue to the solitary nucleus, primary gustatory cortex and finally, the secondary gustatory cortex
- Gustation
- Chemicals in saliva stimulate receptor cells on surface of tongue
- Receptor cells send signals to brain via cranial nerves, vagus and facial nerves
- Information goes to Medulla, then Thalamus, then cortex
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