Special Sensory Pathways (Quiz 3) Flashcards
What are the 4 types of receptors that detect chemicals and project this info to the CNS?
1) visceral chemoreceptors (pH, glucose, oxygen, hormones)
2) gustatory receptors (taste)
3) olfactory receptors (smell)
4) general chemical sensations (peppers, stings, cooling) + general tactile for gustation
Where does the olfactory system begin?
at the olfactory epithelium (superior surface of the nasal cavity)
What CN sensory endings is located in the olfactory epithelium?
CN V (noxious)
What nerve classification do olfactory receptors have?
bipolar neurons
What axonal classification do olfactory neurons have?
C fibers (these are the thinnest, and are unmyelinated axons)
The olfactory nerve (CN 1) axons bundle and pass through cribriform plate to form…
olfactory bulb
How many different types of receptors and genes are there for olfaction?
300 different receptors, 1000 different genes
she may ask this bc she kept repeating it in class
Which cell is found within the olfactory bulb?
mitral/tufted cells
What is the stem cell called that is found in olfactory epithelium?
basal cell
Can you smell anything in super dry environments?
no the receptors are only capable of binding odors in moist environments, so anything super dry will result in no smell.
define odor
anything that binds to the cilia in the nose
What is the olfactory pathway?
1) olfactory receptor cells (dendrites)
2) olfactory nerves
3) olfactory bulb (mitral and tufted cells/neurons)
4) olfactory tract
5) olfactory striae (divides into medial and lateral stria)
6) olfactory cortex
7) output targets of the olfactory cortex
What is the ONLY sensory pathway that foes not use the thalamus?
olfactory pathway
The olfactory bulb is an outgrowth of the….
telencephalon
The olfactory bulb sends axons in what directions?
caudally and laterally
The lateral olfactory tract curves up into the _____________ lobe where the fibers disperse and terminate
temporal
Where does the olfactory pathway terminate?
primary olfactory cortex and amygdala
Different odorants activate different sets of _____________ in patterns
glomeruli
(there odors are compared to known saved patterns of smell (memory))
What are the 2 olfactory cortexes called?
1) piriform cortex
2) entorhinal cortex
What is known as the emotional system?
limbic system
What is known as the memory area?
hippocampus
The olfactory cortex is in which lobe?
temporal lobe
T/F: gustation involves olfaction and vision
true
Which CN sensory input is involved with gustation?
CN V
Taste buds (neurons) are organized within and on ___________
papillae
What CNs innervate taste buds?
facial, glossopharyngeal, and vagus n.
Which nucleus do facial, glossopharyngeal, and vagus n. project to?
solitary nucleus
Which CN transmits texture, temp, and pain in regards to gustation?
CN V
Where are circumvallate (v shaped) papillae located?
back of the tongue (posterior 2/3 of tongue)
Where are fungiform papillae located?
body of tongue (middle, anterior 2/3 of tongue)
Where are filiform (hairlike) papillae located?
tip of tongue
Which papillae does not transmit taste but does transmit texture and movement?
filiform papillae
How many taste buds does each fungiform papilla have?
3-5 taste buds
How many taste buds does each circumvallate papilla have?
250 taste buds
Receptors within taste buds that perceive sweetness is located at tip of tongue. What CN is involved here?
facial n.
Receptors within taste buds that perceive bitterness is located on the back of tongue. What CN is involved here?
glossopharyngeal n.
Receptors within taste buds that perceive osmolarity (water) is located in the back of the tongue. What CN is involved here?
vagus n.
Taste cells have epithelial origin but are very much like neurons. What are some of their functions?
-produce receptor potentials
-respond to chemicals (ingested stimuli)
-make typical synapses on cranial nerves
-some produce action potentials
-BUT they only 8-14 days then replaced (not neural)
Which taste category is involved with the AA glutamate
umami (earthy, rich, aged taste)
How many taste buds are on the average tongue?
5000
For the olfactory system, from the nucleus of the solitary tract in the rostral medulla (input from CN VII, IX, and X). Axons project up the solitary tract through the pons joining the ______________________ and synapses in the thalamus
central tegmental tract
Chemosensory info from the oral cavity is perceived as ___________
flavor
The input to the solitary nucleus forms 2nd order neurons that do 2 things. What are they?
1) reflex activities (salvation, swallowing (coughing))
2) project- thalamic- cortex. Uncrossed, ipsilateral central tegmental tract
(other projections are to the amygdala, frontal lobe, limbic system, and hypothalamus
