Olfactory Flashcards
the olfactory system lies in the __________ of each nostril
superior part
olfactory mucosa is innervated by _____
CN I & V
CN responsible for irrtitative character of some odorants
CNV trigeminal
Receptor cells for smell sensation are _______
olfactory cells
glia like supporting cells of the olfactory system
sustentacular cells
These are found among the olfactory cells and they secrete mucus onto the _______
Bowman’s glands; olfactory membrane surface
These cells continue to divide to produce new olfactory receptor cells that have short life spans
basall cells
Basal cells produce
olfactory receptor cells
the ones that respond to olfactory chemical stimuli
Olfactory Cilia
odor qualities that can be sensed
floral ethereal musky camphor putrid pungent pepperminty
olfactory cilia have _______ long molecules that thread their way thru the membrane about 7 times
receptor proteins
the inside folding of receptor proteins is coupled to a ________ made of ______
G-proteins; 3 subunits
What are olfactory bulb and tract
anterior outgrowths of brain tissue from the brain’s base
anterior
outgrowths of brain tissue from the brain’s
base.
olfactory bulb and tract
the olfactory bulb lies over the _______
cribriform plate
the olfactory bulb separates the ______ from the _______
brain cavity from the upper nasal cavity
These allow small nerves to pass from the olfactory membrane to the olfactory bulb
cribriform plate perforations
the cribriform plate perforations allow small nerves to pass from________ to ______
olfactory membrane to olfactory bulb
where does the olfactory cells’ axon terminate
globular glomeruli within the olfactory bulb
principal cells of the olfactory bulb
mitral cells
olfactory cells are ______ and _____
excitatory and glutaminergic
the mitral cells project through the __________ and ________ to the ______ and _______
olfactory tract and lateral olfactory stria to the
primary olfactory cortex and amygdala.
Mitral & tufted cell bodies lie in the _______ superior to the ________.
olfactory bulb; glomeruli
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter
synapse
what are synapses
junction between 2 nerve cells with a minute gap where impulses pass by diffusion of a neurotransmitter
the dendrites of mitral and tufted cell bodies receive synapses from
olfactory neurons
inhibitory neurons connecting 1 glomerulus to another
periglomerular cells
these make reciprocal synapses with mitral and tufted cells
granule cells
olfactory bulbs contain _______ and _______
periglomerular cells and granule cells
mitral or tufted cells excite granule cells by releasing _____
glutamate
what inhibit mitral or tufted cells
granule cells
the mitral or tufted cells release glutamate to
excite granule cells
odorant substance binds with _________ in the ___________
receptor proteins; olfactory cilium membrane
on excitation of receptor protein what happens then
an alpha subunit breaks away from the G-protein
alpha subunit activates _______ attached to the inside of the ciliary membrane near the receptor cell body
adenylyl cyclase
what does the adenylyl cyclase do
converts ATP to cAMP
cAMP activates
gated sodium ion channel
Na ions increase ______ in the ______ direction
electrical potential; positive
olfactory neuron excitation and AP transmission into CNS via ______-
olfactory nerve
_______ are the only substances that can be sniffed into the nostrils can be smelled
volatile substances
Stimulating substances must be atleast
slightly water soluble and slightly lipid soluble
why stimulating substances must be lipid soluble
lipid constituents of the cilium are a weak barrier to nonlipid soluble odorants
rate of olfactory nerve impulses corresponds to
logarithm of stimulus strength
olfactory receptors adapt about _______ in the 1st second after stimulation
50%
where does most additional adaptation to smell occurs
within the CNS
Where does centrifugal nerve fibers pass and its direction along the olfactory tract
olfactory regions of the brain; backward
centrifugal nerve fibers terminate on ______ in the ______
special inhibitory granule cells in the olfactory bulb
What happens to CNS after onset of olfactory stimulus
it develops strong feedback inhibition to suppress relay of smell signals through the olfactory bulb
smell is concerned more with detecting ______ than _____
presence or absence of odors than quantitative detection of intensities
Part of the brain that originally subserved
olfaction evolved into the
limbic system
ipsilateral olfactory trigone aka
olfactory tubercle
integrated signals pass along the olfactory tract and centrally diverge to the ______ or terminate in the _______. axons then project to the _______
anterior commisure; ipsilateral olfactory trigone; primary olfactory cortex, entorhinal cortex and amygdala
Brodman’s area for primary olfactory cortex
34
the brimary olfactory cortex overlies the
uncus
olfactory tract enters the brain at the _________, between _____ and ______-
anterior junction between mesencephalon and cerebrum
the olfactory tract divides into pathways, one going to _______ and the other to _______
medial olfactory area; lateral olfactory area
the septal nuclei feed into the ______ and _____
hypothalamus and other primitive limbic system portions
this feed into the hypothalamus &
other primitive limbic system portions
septal nuclei
medial olfactory area aka
very old olfactory system
lateral olfactory area aka
less old olfactory area
lateral olfactory area is composed of
prepyriform cortex and cortical portion of the amygdaloid nuclei
the lateral olfactory area does not pass through the
thalamus
only area that does not pass first
through the thalamus.
lateral olfactory area
inability to smell
anosmia
diminished olfactory sensitivity
hposmia or hypesthesia
hyperosmia
enhanced olfactory sensivity
this may cause olfactory hallucinations
lesions in the parahippocampal uncus
