Smell and Taste Flashcards
what receptors are smell and taste forms of?
chemoreception
where are the olfactory receptors found
in the olfactory epithelium (at the top of the nose)
how many receptors cells does the epithelium contain
10 million receptor cells and covers 3 cm squared in each side
what colour is our epithelium
pale yellow
ciliated neurons
single dendrite that extends into the olfactory epithelium
nonmotile cilia
the receptors neurons branches to form nonmotile cilia that. increase the surface area of cell so it has greater chance of catching odorant’s
how many kinds of odorant receptors do we have
400
how many g coupled protein receptors genes do we have
1000 or 3-5% of the genome, but only 400 are expressed in humans
what happens when odorant molecule binds to its receptors
it will bind to its receptor G(olf) which increases the concentration of cAMP. cAMP gated channels open, depolarizing the neurons and triggering an action potential that travels to the olfactory bulb
how many cells must react before we experience a smell
40 cells
Properties of olfactory receptor cells
pinocytotic, continually sipping in fluid and sending it along the nerves into the brain
short lived, degenerating after a month or 2 that will be replaced by new ones
olfactory bulb
extension of the cerebrum and lies on the underside of the frontal lobes
olfactory nerve
projection from the receptors to the bulb
convergence in olfactory receptors
many receptor cells converge on each bulb neuron
how does our smell pathways bypass the thalamus
the bulb projects directly to the olfactory cortex
where is the olfactory cortex located?
in the frontal and temporal lobe
where else does the bulb project to? wHy?
limbic system. because evolutionarily smell was tied to motivation
pheromones
chemicals released by an animal into the environment which affect the physiology or behaviour of other members of its species
what do rats have in their nasal cavity that is involved in their behavioural responses to sex pheromones
Vomeronasal organ (VNO)
where are our main taste receptor cells
in taste buds on our tongue
how many taste buds do we have? How are they distributed
- mainly on the top of the tonguee but also on the soft palate, epiglottis and upper esophagus
how many taste buds do babies have
10,000
how many receptor cells does each bud have
100- epithelial cells
how many kinds of receptor does a typical taste bud contain
sweet and umami cells: detect sugar and glutamate (protein)
bitter: poison
salty and sour: detect Na and H
receptor for fatty acids
