Lecture 8- Olfaction Flashcards
odor
the translation of a chemical stimulus into a smell sensation
odorant
molecule that is defined by its physiochemical characteristics, which are capable of being translated by the nervous system into the perception of smells
to be smelled… odors must be:
small
volatile (float through the air)
hydrophobic (water-repellent)
stimulus for olfaction
a single molecule, or amalgam, of a volatile substance
volatility
tendency of a substance to “vaporize”; for molecules to detach from a liquid or solid
olfactory cleft
narrow space at the back/top of the nose into which air flows, where the main olfactory epithelium is located
olfactory epithelium
a secretory (thing that secretes) mucous membrane in the human nose whose primary function is to detect odorants in inhaled air
olfactory epithelium mucosa
on the roof of the nasal cavity
supporting cells
provide metabolic and physical support for the olfactory sensory neurons
olfactory sensory neurons (OSN)
main cell type in the olfactory epithelium.
- small neurons located beneath watery mucous layer in the epithelium
basal cells
precursor cells to olfactory sensory neurons (can differentiate to replace other epithelial cells)
olfactory cilia
project through the mucous and are the receptor sites for odorant molecules
cribriform plate
bony structure riddled with tiny holes, at the level of the eyebrows, that separate the nose from the brain
Olfactory nerves
axons of the olfactory sensory neurons bundle together after passing through the cribriform plate to form the olfactory nerve
olfactory bulb
blueberry sized extension of the brain just above the nose, where olfactory info is first processed
how many olfactory bulbs are there?
2- one in each hemisphere
- connections are ipsilateral
anosmia
the total inability to smell, most often resulting from sinus illness or head trauma
parosmia
common sequelae of smell loss, associated with COVID-19, with onset on average of 3 months after initial infection
hyposmia
partial loss of smell
ageusia
loss of taste
hypogeusia
partial loss of taste
True or false: the olfactory bulb relays information through the thalamus
FALSE: smell is the only sense that doesnt use the central relay station
primary olfactory cortex
neural area where olfactory info is first processed. Includes:
amygdala
parahippocampal gyrus
entorhinal cortex
limbic system
encompassing groups of neural structures that include:
olfactory cortex
amygdala
hippocampus
piriform cortex
entorhinal cortex
- involved in many aspects of emotion and memory
