Smell and Taste Study Guide

olfactoring sensory neurons

receptor cells with cilia that increase surface area for odor detection - located in the superior nasal concha, the primary receptor cell for smell

supporting cells

surround olfactory sensory neurons to nourish them. columnar in shape and make up the epithelial membrane, produces mucous that captures and dissolves odorants

olfactory stem cells

located at the base of the epithelium, they regenerate sensory neurons that only have a 30-60 day lifespan

bipolar neuron

type of neuron that describes an olfactory receptor cell, with a thin apical dendrite that terminates in a knob where cilia radiate from

olfactory cilia

the site of olfactory transduction, where odorant binding molecules bind to their receptors

step 1 of smell transduction

step where an odorant binding molecule binds to cilia on a receptor cell

step 2 of smell transduction

step where a G protein is activated in response to receptor binding, activating adenylyl cyclase

step 3 of smell transduction

step where ATP is converted to cAMP, which opens Na+ and Ca2+ channels

step 4 of smell transduction

step where depolarization occurs and APs are sent to the olfactory bulb

olfactory impulse pathway

olfactory sensory neuron>olfactory bulbs>2nd order mitral cells>piriform lobe>frontal lobe or limbic system

fungiform, vallate, and foliate

types of papillae on the tongue

fungiform papillae

mushroom shaped papillae scattered over the entire tongue surface but contain 1-5 taste buds each

vallate papillae

largest and least numerous papillae formed an inverted V at the back of the tongue, containing many taste buds

foliate papillae

papillae located laterally on the tongue with many taste buds in childhood but fewer with age

gustatory epithelial cells

the receptor cells for taste

gustatory hairs

long microvili that project from the tips of gustatory epithelial cells and extend through a taste pore to the surface of epithelium

serotonin

NT released by one type of gustatory epithelial cell in a traditional synapse with its sensory dendrites

ATP

NT released by another type of gustatory epithelial cell, though lacking synaptic vesicles

sweet

taste sensation elicited by many organic substances and certain lead salts

sour

taste sensation produced by H+ ions in solution (i.e. acid)

salty

taste sensation produced by metal ions

bitter

taste sensation produced by alkaloids and some non-alkaloid substances

umami

taste sensation produced by amino acids glutamate and aspartate

salty

taste sensation that is due to Na+ influx through Na+ channels, directly depolarizing gustatory epithelial cells

sour

taste sensation mediated by H+ which enters through a specific channel to cause direct depolarization and release of Ca2+

bitter, sweet, and umami

three taste sensations all sharing a G protein mechanism coupled receptor, activation leading to release of Ca2+ channels, depolarization, and ATP as an NT

CN VII/facial nerve

cranial nerve transmitting impulses from the anterior 2/3 of the tongue

CN IX/glossopharyngeal nerve

the lingual branch of this cranial nerve transmits impulses of the posterior third of the tongue and pharynx

CN X/vagus nerve

cranial nerve serving taste buds in the epiglottis and lower pharynx

gustatory pathway

cranial nerves>solitary nucleus in medulla>thalamus>gustatory cortex in insula