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20 Cards in this Set

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  • Back
What provides friction that helps the tongue to move objects around in the mouth
What contains about 5 tastbuds; scattered over entire surface of tongue
Containes about 100 taste buds
-Largest of papillae
-7-12 form an inverted V at back of the tongue
Supporting Cells
-Form bulk of taste bud.
-Insulate receptor cells from each other as from surrounding tongue epithelium
Basal Cells
Divide and differentiate into supporting cells >>> new gustatory cells
What role do microvilli play in detecting taste?
Long microvilli called taste hairs project through small opening.
What 3 processes must happen in order for a taste to be detected?
1. Chemicals dissolved in saliva come in contact with taste hairs>>bind to receptor proteins of the gustatory cells
2. Differet taste involves different receptors.
-Depolarization of cell membrane as a result of chemically gated ion channels opening up or
-G proteins>use secondary messengers to produce their effects. (Transmits info to nucleous to stimulate)
3. Results in neurotransmitters released by receptor cell>>Action Potential of the afferent fiber.
-Threshold for receptor stimulation varies for each of the primary taste senstations.
-Taste receptors respond more quickly to unpleasant that pleasant stimuli
What is the gustatory pathway?
Taste buds are monitored by Cranial nerves Vii, IX, and X.
-Facial nerve - monitors all teh taste buds from anterior 2/3>tip of tongue>circumvalllate
b. Glossopharyngeal - monitors posterior 1/3 of tongue & circumvallate
C. Vagus - Innervates taste buds scattered on pharynx & larynx
2. Sensory afferents carried by these cranial nerves synapse in Medulla Oblongata
3. Postsynaptic joins someatic axons that carry infomation on touch, pressure, prorioception>>Thalmus
4. Another synapse in thalamus>gustatory center
Which reflexes are triggered by taste?
-Increase in saliva and gastic juices
-Gaggins or reflexinve vomiting
What is gustatory discrimination?
4 primary taste - sweet, sour, salty, & bitter
-Taste receptors differe in their sensitivity to tastes.
Salty and Sweet --> anterior (tip) of tongue
Sour and Bitter --> posterior (back) of tongue
Pleasant taste charachteristic of beef broth, chicken broth, and parmesan cheese; found in circumvallate papillae
Water receptors in phrarynx sensory output of these receptor.
Hypothalamus - affects systems involved ini H2O balance
What is the location and structure of olfactory epithelium?
Contains olfactory receptors, supporting cells & basal cells.
Supporting cells (Olfactory epithelium)
Surround & cushin olfactory receptor cells
Basal Cells/stem cells (Olfactory epithelium)
Found at base of epithelium; divide and differentiate into supporting cells or new olfactory receptor cells.
Olfactory receptor cells.
-highly modified neurons - thin apical dendrite > ends in a knob > several long cilia radiate from knob > OLFACTORY CILIA
-Olfactory cilia - increases receptive surface area; covered within a thin layer of mucus; mucus traps & dissolves airborne odor moleculese - mucus renewed continuously (produced by supporting cells & glands in underlying c.t.)
-unmyelinated axons of olfactory receptor cells form fiber bundles >>>Olfactory nerve
-bundles project through openings in cribiform plate - bundles synapse in olfactory bulbs
Trace the olfactory pathway
-Odor molecules come in contact with olfactory cilia
-Dissolved chemicals - stimulates olfactory cilium membrane > opens Na+ channels
-Depolarrization>action potential>impulse transmitted along the axons of receptor cells
-Axon of receptor cells come together > form olfactory nerve fiber bundles
-Synapse in olfactory bulbs with mitral cell (type of neuron)
-mitral cells are activated>impulses flow from olfactory bulbs via olfactory tracts to: Olfactory cortex and Hypothalamus emotional aspects of smells are analyzed & responded to)
Discuss the relationship between granule and mitral cells.
Mitral cells are second-order neurons. Granule cells inhibit mitral cells so that only highly excitatory olfactory impulses are transmitted.
Discuss the emotional aspects of smell
-Olfactory bulbs - house granule cells that inhibit mitral cells(so that only highly excitatory olfactory impulses are transmitted) - granule cells allow employees of Bondi's island to still enjoy thier lunch.
-Aromas of food are perceived differently (starving vs. just eaten)
-Smells associated with danger triggers SNS fight or flight response.
-Appetizing odors - increase salivation & stimulates digestive tract Unpleasant odors - trigger protective reflexes > sneezing, coughing.
Explain olfactory discrimination
-Olfactory system can make subtle distinctions among 2000-4000 chemicals
*no apparent structural differences exist amoung the olfactory receptor cells
*at least 50 primary smells
*not completely understood>appears the CNS interprets each smell on the basis of the overall pattern of receptor activity
*some smells are detected in very small concentrations (ex. beta-mercoptan (added to natural gas)