Special Senses Flashcards
Special senses
Specialised sense organs that gather sensory information and change it into nerve impules
Eg: vision, hearing, balance, taste, smell
General senses
All associated with the sense of touch, lack special sense organs
Information gathered by skin and other body tissues
Olfactory system
Transmits sense of smell from olfactory epithelium of nasal mucosa to the olfactory cortex of the brain
Olfactory pathway
Olfactory epithelium and olfactory nerves > olfactory bulb > olfactory tract and olfactory striae > olfactory cortical areas
Olfactory epithelium (1st order)
Olfactory receptor cells
Supporting cells
Basal/progenitor cells
Madeleine effect
Olfactory bulb (limbic system), close to amygdala (associated with emotion) and the hippocampus (associated with memory)
When you first encounter a smell it becomes linked to emotions felt at that time. Encountering the smell again can evoke the memory and associated emotion
Disorders of sense of smell
Tumour - can compress the olfactory bulb and cause loss of smell
Cells within the taste buds
Gustatory cells
Supporting cells
Name the 5 basic flavours
Sweet
Sour
Salty
Bitter
Unami
Taste neurons
1st order - carry taste sensation from taste buds to NTS
2nd order - from NTS in medulla oblongata to thalamus
3rd order - from thalamus to the post-central gyrus of the parietal lobe
Vision neurones
1st order - (bipolar cells of retina) receives visual information from rods & cones
2nd order - (ganglion cell of retina) from optic nerve through optic chiasm and optic tract
3rd order - (lateral geniculate nucleus in thalamus) project to visual cortex as optic radiation
Visual pathways
DORSAL - calculates objects location
VENTRAL - creates a sense of perception
Rod cells
Detect in low light, don’t detect colour
Cone cells
Detect in high light intensity, detect colour
Vestibular nerve
Responsible for the efferent and afferent fibres that control balance and equilibrium
Cochlear nerve
Carries efferent and afferent fibres for hearing
Hearing neurons
1st order - bipolar neurons of spiral ganglion in cochlear nerve
2nd order - dorsal and ventral cochlear nuclei in the medulla oblongata
3rd order -
Describe hearing
- Sound waves travel through external auditory canal and vibrate Tympanic membrane
- Vibrations are transmitted through the oval window causing a wave through the endolymphatic fluid
- This vibrates the organ of Corti’s basilar membrane, stimulating inner & outer hair cells
- Hair cells transmit action potentials to bipolar neurones in the spiral ganglion
Vestibular neurone
1st order - vestibular ganglion
2nd order - vestibular nuclei in medulla oblongata
3rd order - thalamus
What are the order of neurones
1st order - receive impulses and send them to spinal cord
2nd order - send impulses to the thalamus and cerebellum
3rd order - carry signals from thalamus to the primary sensory cortex
What is the first order neuron
From spinal nerve to spinal cord
What is the sencond order neuron
From the spinal cord to the thalamus
What is the third order neuron
From the thalamus to the cerebral cortex
