CHEMICAL SENSES Flashcards
RECEPTOR TYPES: Bipolar cells embedded in the olfactory epithelium
Pathways to Connection:
Axons from the receptors synapse in the glomeruli of the olfactory bulbs. *
Axons from the olfactory bulbs form the olfactory tract and synapse in the olfactory cortex. *
The olfactory cortex sends information to the thalamus, limbic system, insula, and orbitofrontal cortex.
Olfaction
RECEPTOR TYPES: Taste buds on the tongue and elsewhere in the mouth
PATHWAYS AND CONNECTION:
* Fibers serving the taste receptors join cranial nerves VII, IX, and X.
- These axons synapse in the gustatory nucleus of the medulla.
- Axons from the gustatory nucleus synapse in the ventral posterior medial (VPM) nucleus of the thalamus.
- VPM axons synapse in somatosensory cortex and in the orbitofrontal cortex.
Taste
sense of smell.
Olfaction
The layer in the nasal cavity containing olfactory receptors.
Olfactory Epithelium
Structures found within the olfactory bulbs.
Glomeruli
A fiber pathway connecting the olfactory bulbs to the olfactory cortex.
Olfactory Tract
Cortex in the frontal lobe that responds to the sense of smell.
Olfactory Cortex
One of the five basic taste groups, characteristic of tastes found in seaweed and other “meaty or savory” elements of Asian cuisine.
Umami
Bumps on the tongue containing taste buds and taste receptors.
papillae
Small fibers extending from taste receptors.
microvilli
The nucleus of the thalamus that receives information regarding taste.
ventral posterior medial (VPM) nucleus of the thalamus
Unlike many other types of neurons, olfactory receptor cells regularly die and are replaced in a cycle lasting approximately ____________
four to six weeks.
In each glomerulus, approximately _______ olfactory receptor axons form synapses on about 100 olfactory neurons
25,000
begins with the dissolving of molecules in the saliva of the mouth
Taste
Four major categories of Taste
Sweet, Sour, Salty and Bitter
Each bump on the surface of the tongue, known as a papilla, contains somewhere between _____ taste buds, which are too small to be
seen with the naked eye
1 and 100
Most taste buds contain somewhere between ___________ taste receptor cells. The taste receptor cells are not technically considered to be neurons, although they do have the capability of forming synapses. Each taste receptor has a number of thin fibers known as microvilli that
extend into the saliva
50 and 150
Taste Pathways
Taste Receptor Activation > Nerve Transmission > Central Processing
Taste sensations begin when taste
buds on the tongue and other oral structures are activated by
various chemicals in food and drink. Taste receptors detect
sweet, sour, salty, bitter, and umami tastes.
Taste Receptor Activation
Sensory nerves, primarily the facial (VII)
and glossopharyngeal (IX) cranial nerves, transmit taste signals
from the taste buds to the brainstem, where they synapse.
Nerve Transmission
After synapsing in the brainstem, taste
signals travel to the thalamus and then to the gustatory cortex
in the brain’s insula and frontal operculum, where they are
processed and perceived as specific taste qualities.
Central Processing
