module 7 Flashcards
five special senses
smell, taste, hearing, vision, balance
three receptors
mechanoreceptors, photoreceptors, chemoreceptors
mechanoreceptors
hearing and balance
photoreceptors
vision
chemoreceptors
smell and taste
physiology of smell
- odorant must be volatile (gaseous)
- odorants must reach olfactory epithelium and dissolve in mucus
- odorant then binds to receptors and opens gated
channels - generate an action potential
olfactory pathway
- olfactory sensory neurons form olfactory nerve (CN I)
- action potentials travel to olfactory
cortex of temporal lobe - from olfactory cortex the information takes 2 pathways
1 to frontal lobe: smell consciously interpreted and
identified
2 some information travels to hypothalamus and
other regions of limbic system: emotional
responses to odour elicited
physiology of taste
- food chemical must be dissolved in saliva
- the food chemical must diffuse into the taste pore
- the food chemical must contact the gustatory hairs
- the food chemical binds to the receptor of the hair cells
- action potential is generated
gustatory pathway
- Facial (VII), Glossopharyngeal (IX) and Vagus (X)
nerves carry action potentials from taste buds to - gustatory cortex of the insula
- hypothalamus and limbic system (appreciation of
taste)
three major areas of the ear
- External (outer) ear – hearing only
- Middle ear (tympanic cavity) – hearing only
- Internal (inner) ear – hearing and balance
external ear consists of
pinna, external acoustic meatus, tympanic membrane
pinna
funnels sound waves into the external acoustic meatus
external acoustic meatus
sound waves entering external acoustic meatus travel to and vibrate tympanic membrane
tympanic membrane
vibrates in response to sound waves which then transfers sound energy to bones of middle ear
middle ear consists of
auditory ossicles (malleus, incus, stapes), pharyngotympanic tube
auditory ossicles function
transmit and amplify the vibratory motion of the tympanic membrane to the oval window
pharyngotympanic tube function
equalises air pressure in the middle ear cavity with external air pressure
internal ear consists of
body labyrinth and membraneous labyrinth