chapter 16

Question 1

what are the five basic taste qualities

Answer 1

salty
sour
sweet
bitter
umami

Question 2

what three components are involved in the chemical senses

Answer 2

taste:
- occurs when molecules enter the mouth in solid or liquid form and stimulate receptors on the tongue

olfaction:
- occurs when air borne molecules enter the nose and stimulate receptor neurons in the olfactory mucosa located on the roof of the nasal cavity

flavor:
- the impression we experience from the combination of taste and olfaction and several other factors

Question 3

neurogenesis

Answer 3

constant renewal of the receptors unique to taste and smell
- because they get exposed to harmful materials

olfactory receptors: cycle of birth, development, and death = 5-7 weeks

taste receptors = 1-2 weeks

Question 4

how do chemical senses act as gatekeepers?

Answer 4

1. identify things that the body needs for survival and that should therefore be consumes
2. detect things that would be bad for the body and that should therefore be rejected

Question 5

emotional components of the chemical senses

Answer 5

things that are bad for us often taste or smell unpleasant

things that are good for us generally taste or smell good

smelling an odor associated with a past place or event can trigger memories, which in turn may create emotional reactions

Question 6

taste quality and substance effect

Answer 6

sodium chloride (salty)
hydrochloric acid (sour)
sucrose (sweet)
quinine (bitter)

potassium chloride (both salty and bitter components)
sodium nitrate (salty, sour, and bitter)

Question 7

taste quality and associations

Answer 7

sweetness: associated with substances that have nutritive value

bitter: associated with substances that are potentially harmful

salty: presence of sodium
connection isnt perfect

Question 8

types of papillae on the tongue

Answer 8

filiform: shaped like cones and located over entire surface

fungiform: series of folds on back and sides

foliate: series of folds along the back of the tongue on the sides

circumvilliate: shaped like flat mounds in a trench located at back

Question 9

where are taste buds located

Answer 9

in papillae (except for filiform)

Question 10

how many taste buds does the tongue contain?

Answer 10

10,000 taste buds

Question 11

taste cells in taste buds

Answer 11

each bud has 50-100 taste cells with tips that extend into the taste pore

Question 12

when does transduction in taste cells occur

Answer 12

when chemicals contact the receptor sites on the tips

Question 13

what are the four pathways for signals from taste cells

Answer 13

chorda tympani nerve from front and sides of tongue

glossopharymngeal nerve from back of tongue

vague nerve from mouth and throat

superficial petronasal nerve from soft palate

Question 14

where do taste pathways connect

Answer 14

in the solitary tract in the spinal cord

from there, they go to the thalamus and then to areas in the frontal lobe:
- insula
- frontal opervulum cortex
- orbital frontal cortex

Question 15

arguments for population coding in taste

Answer 15

Erickson: found that nerve fibers responded in population coding style for different taste stimuli in rats
- also found that similar tastes had similar patterns of firing, as population coding would predict

Question 16

specificity coding

Answer 16

• we have receptors that respond specifically to a particular taste - ex. adding bitter taste receptors in mice makes them avoid bitter tasting things
• also have neurons that respond selectively to specific stimuli/a number of specific stimuli
• amiloride (a substance that blocks the flow of sodium into taste receptors) - applying it to the tongue of a rate decreases responding to neurons that react to salt, but not others

Question 17

anosmia

Answer 17

loss of the ability to smell due to injury or infection

Question 18

papillae

Answer 18

the structures that give the tongue its rough appearance - there are four kinds, each with a different shape

Question 19

taste buds

Answer 19

contained on the papillae (except filiform) - about 10,000 taste buds

contains 50 to 100 taste cells

Question 20

taste cells

Answer 20

cells that make up a taste bud - each bud contains a number of cells, and the tip of each one sticks out into a taste pore

one or more nerve fibers are associated with each cell

Question 21

receptor sites

Answer 21

sites located on the tips of the taste cells

there are different types of sites for different chemicals - chemicals contacting the sites cause transduction by affecting ion flow across the membrane of the taste cell

Question 22

why does stimulation on the central part of the tongue cause no taste sensations

Answer 22

because it only contains filiform papillae, which have no taste buds

Question 23

taste pore

Answer 23

an opening in the taste bud through which the tips of taste cells protrude. when chemicals enter a taste pore, they stimulate the taste cells and result in transduction

Question 24

nucleus of the solitary tract

Answer 24

the nucleus in the brain stem that receives signals from the tongue, the mouth, and the larynx transmitted by the chorda tympani, glossopharyngeal, and vagus nerves

Question 25

insula

Answer 25

area in the frontal lobe of the cortex that receives signals from the taste system and is also involved in the affective component of the perception of pain

Question 26

frontal operculum

Answer 26

an area in the frontal lobe of the cortex that receives signals from the taste system