the chemical senses: smell and taste (2.5)

Question 1

olfaction (smell)

Answer 1

airborne; the response of the olfactory system to airborne chemicals that are drawn by inhalation over receptors in the nasal passages

Question 2

gustation (taste)

Answer 2

mouth; the response of the gustatory system to chemicals in solution to the oral cavity

Question 3

pheromones

Answer 3

chemicals that influence the physiology and behavior of conspecifics (members of the same species)

Question 4

olfactory receptor cells

Answer 4

located in the upper part of the nose (nasal epithelium); embedded in a layer of mucus-covered tissue (olfactory mucosa); regularly replaced (neurogenesis)

Question 5

odorant binding proteins

Answer 5

made by the support cells that drag the odor into the mucus and bring it to the receptors

Question 6

population code

Answer 6

cells have many different odors that they are sensitive to; need to compare a smell across all receptors because they are generalists (like many different odors); way of distinguishing smell

Question 7

transduction (direct or indirect)

Answer 7

indirect

Question 8

transmission (direct or indirect)

Answer 8

direct

Question 9

dominant ion

Answer 9

chloride (amplifier)

Question 10

olfactory bulb

Answer 10

where axons of olfactory receptor cells synapse on neurons that project via the olfactory tracts to the brain

Question 11

olfactory glomeruli

Answer 11

discrete clusters of neurons that lie near the surface of the olfactory bulbs; each receives input from several thousand olfactory receptor cells

Question 12

mitral cells

Answer 12

“dip their toes” into one glomerulus or another; receive information from the axons of olfactory receptor neurons and form synapses in glomeruli

Question 13

olfactory tract

Answer 13

projects bilaterally to medial temporal lobe structures including the piriform cortex and the amygdala; only system that does not first pass through the thalamus

Question 14

pathways from medial lobe (2)

Answer 14

limbic system: emotional response to odors
thalamus-orbitofrontal cortex: conscious perception of odors

Question 15

basic tastes (5)

Answer 15

sweet, sour, salty, bitter, umami

Question 16

flavor

Answer 16

not the same as taste; a highly multisensory percept depending on taste, smell, vision (color), audition (bite), and somatic senses (texture, temperature, pain)

Question 17

papillae (4)

Answer 17

filiform papilla: fill in vast majority of tongue but do not have taste buds
circumvallate, foliate, fungiform papillae: have the taste buds

Question 18

transduction (direct or indirect)

Answer 18

direct (salty and sour; Na+)
indirect (bitter, sweet, umami; Ca2+)

Question 19

secondary gustatory cortex

Answer 19

in the orbitofrontal lobe; chemical and non-chemical (via the ventral stream) senses can merge to produce the percept of flavor

Question 20

anosmia (definition and causes)

Answer 20

anosmia: inability to smell
causes: blows to the head that damage the olfactory nerves; tumors on the olfactory tract

Question 21

ageusia (definition)

Answer 21

inability to taste (rare -> must lose cranial nerves 7, 9, and 10)