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67 Cards in this Set
- Front
- Back
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What are the 4 categories that the receptors for visceral function fall into?
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1. visceral chemoreceptors
2. gustatory receptors 3. olfactory receptors 4. chemosensitive endings |
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Where are the visceral chemoreceptors and what do they maintain?
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scattered throughout the body and maintain balance in oxygen, gluscose, and hormones.
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What do the gustatory receptors mediate?
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taste
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What do the olfactory receptors mediate?
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sense of smell
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Where are the chemosensitive endings found and what do they do?
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(common chemical sensation)
found in the mucous membranes that monitor chemical agents e.g. capsaicin-burning of chili peppers, coldness of menthol, sting of ammonia |
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What are taste bug receptors innervated by?
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cranial nerves VII, IX, and X
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Define taste.
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taste is a complex phenomena that is mediated by several cranial nerves.
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The tongue is covered by bumps called?
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papillae
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What 3 things are included in the subpopulation of papillae that contain taste buds?
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fungiform
foliate circumvallate papillae |
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Where do about 200-300 fungiform papillae (shaped like a mushroom) scatter across?
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the anterior 2/3s of the tongue, with concentrations on the tip and sides
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How many taste buds does each fungiform papillae have?
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3-5
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What are foliate papillae shaped like and where are they found?
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leaf shaped
found in folds on the posterior of the tongue |
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What are fungiform papillae shaped like?
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mushroom
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Each fold of foliate papillae contains how many taste buds?
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100-150
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Where is the circumvallate papillae arranged?
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(surrounded by a wall)
arranged in a V line in 2/3s of the back tongue |
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What are each of the circumvallate papillae surrounded by? How many taste buds do they contain?
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a deep groove and contain 250 taste buds
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What fraction of all taste buds are circumvallate papillae? What is the average # of circumvallate papillae a person has?
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1/2
5,000/person on avg. |
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Although variable, taste buds are on the _____ and _______, though few and only in children.
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palate
pharynx |
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What does the facial nerve innervate?
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the fungiform and anterior foliate papillae and the palate
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What does the glossopharyngeal nerve innervate?
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the circumvallate and most foliate papillae and the pharynx
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What do a few axons from the vagus innervate taste buds of the _______ and ______.
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epiglottis and esophagus
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What are the 4 categories of taste sensations?
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sweet sour salty bitter
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How is salt transduced?
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directly transduced by the presence of high levels of sodium ions (Na+). Na+ channels in the apical portions of the taste receptor cells allow the inward movement of Na+ ions, depolarizing the cell.
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Why do acids taste sour?
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acids taste sour due to the presence of H+ ions. which depolarize receptor cells either by the movement of protons through the Na+ channels or by blocking conductance of pH sensitive K+ channels.
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What do sweet compounds bind to?
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sweet compounds bind to G protein-coupled receptor molecules that cause a decrease in the conductance of K+
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What do bitter substances bind to?
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bitter substances either bind to ligand-gated channels and G-protein receptors, or bind to ligand-gated K+ channels and reduce the probability of their opening. Some bitter substances bind to G-protein couples receptor molecules that through a second messenger cause release of Ca+, which in turn causes the release of transmitter by the cell.
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What has been proposed as a 5th gustatory modality?
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MSG
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The nerves that convey information, end in the nucleus of what?
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solitary tract
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What are the 2 tasks that the second order fibers are involved in?
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some are involved in swallowing or coughing through the cranial motor nuclei
others fibers project to the cerebral cortex via the thalamus. These are uncrossed. |
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The second order fibers travel through the ______________ tract to the medial part of the VPM. Fibers then project to gustatory cortex located on the ________ and medial portion of the __________ near the central sulcus. Fibers from the gustatory cortex then project to ____________ where they are thought to join information from the olfactory system. From here they project to the ___________, which sends information to the hypothalamus and limbic system.
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The second order fibers travel through the ____central tegmental tract__________ tract to the medial part of the VPM. Fibers then project to gustatory cortex located on the _Insula_______ and medial portion of the _frontal operculum_________ near the central sulcus. Fibers from the gustatory cortex then project to __orbital cortex__________ where they are thought to join information from the olfactory system. From here they project to the __amygdala_________, which sends information to the hypothalamus and limbic system.
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How are information about taste qualities coded?
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by the pattern of neural activity rather than the type or location of the receptor that receives the information
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What are the exception to the rule that all stimuli that reach neocrotex must first pass through the thalamus?
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olfactory stimuli
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Where do the olfactory stimuli project?
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directly to the telencephalon
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Odorous molecules are drawn into the nasal system during what?
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inhalation
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Humans are capable of distinguishing approx. how many different odorous compounds?
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10,000
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Where are the axons of olfaction found?
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olfactory epithelium
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Describe the olfactory epithelium.
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this a patch of yellowish pigmented cells that occupy approx. a cm^2 area that line the roof and walls of the nasal cavity.
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How many receptor cells does each nasal cavity contain and what are they interspersed with?
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each nasal cavity contains about 5 million receptor cells interspersed with supporting cells and the ducts of small glands.
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Where are the sensory endings of the trigeminal nerve found? What do they respond to?
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found in each nasal cavity
the endings do not respond to smells as much as they respond to noxious odors elicited y irritants (e.g ammonia) |
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Which are true neurons: taste receptors or olfactory receptors?
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olfactory receptors
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Describe the olfactory receptors.
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true neurons
each receptor is bipolar with s small slender dendrite on one side and a long thin axon on the other |
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What does the dendrite in the olfactory receptors extend to?
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a bulbous termination, the olfactory vesicle
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What comes from the olfactory vesicle that spreads out of the surface of the surface epithelium?
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a series of 10 to 30 cilia
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The cilia are embedded in the mucus secreted by what?
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Bowman's gland cells and other supporting cells
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What do odorants need to do in order to stimulate the olfactory receptors?
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they must diffuse across the mucus that has the cilia embedded in it.
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How slowly do un-myelinated axons of the olfactory cells (0.2 um in diameter) conduct?
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about 0.1m/sec
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The un-myelinated axons collect as a group of fibers termed ____________ and project through the ___________ of the ________ bone to terminate in the ________________. These filia collectively make up the first cranial nerve.
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The un-myelinated axons collect as a group of fibers termed __olfactory filia__________ and project through the ___cribiform plate________ of the ___ethmoid_____ bone to terminate in the __olfactory bulb______________. These filia collectively make up the first cranial nerve.
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Olafactory receptors are unique among neurons in that they are what?
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constantly replaced throughout the life of the individual unlike all other neurons
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Olfactory receptors may include up to (how many) different types that process an assorted number of odorants.
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1,000
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In contrast to taste receptors, all olfactory receptors use what?
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receptor proteins that are coupled to G proteins.
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What does each receptor protein bind?
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an array of odorants that overlap, but are somewhat different, to other receptor proteins.
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Each receptor protein binds an array of odorants that overlap, but are somewhat different to other receptor proteins. What does this variation provide the olfactory system with?
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a extraordinary ability to detect many odorous compounds.
Current research indicated that a heavy investment of the total genome is devoted to this process (probably about 10% or more) |
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What does the second messenger cascade set up by odorous compounds cause?
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causes the opening of a cation channel
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When the second messenger cascade set up by odorus compounds causes the opening of the cation channel, the resulting influx of Na+ and Ca+ ions depolarizes what? which may trigger what?
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the receptor cell and may trigger an action potential in the same cell
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Where does the axon of the receptor cell end?
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in the olfactory bulb
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The axon terminal ends in specialized structures, 100-200 um in diameter, is termed what?
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glomeruli
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What are glomeruli and what are they surrounded by? What are they activated by?
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are classic synaptic connections surrounded (insulated?) by glial cells. Each glomeruli is activated by one or a few types of odorous compounds
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In the glomeruli, the axon synapse with ___________ of the olfactory bulb.
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mitral cells
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The axons of the mitral cells form the _________________
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olfactory tract
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Where does the olfactory tract project through? terminate?
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projects through the olfactory bulb and terminates in the inferior frontal lobe and anterior temporal lobe
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The olfactory bulb also contains interneurons called_____?
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granule cells
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The olfactory bulb also contains small projection neurons called? What do these cells do?
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tufted cells that send their axons into the olfactory tract
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Centrifugal fibers also terminate in Glomeruli from other regions of the CNS. What do these fine tune? What do these fibers project from?
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these fine tune olfactory sensation
project from widespread telencephalic regions |
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What are the 6 locations that the projections of the olfactory bulb fibers terminate?
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in the anterior olfactory nucleus
the olfactory bulb pyriform cortex amygdala uncus (periamgdaloid cortex) a small portion of the para-hippocampal gyrus specifically entorhinal cortex |
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Axons also cross the midline through the ___________ to supply the opposite frontal lobe.
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anterior commissure
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What is the McClintock Effect?
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women housed together to regulate their menses cycle.
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What is farming?
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pre-ovulatory cervical mucus mixed with water and sprayed into the noses of cows advance and synchronized the time of estrous
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