Ch7 - Gustation

Question 1

6 qualities of taste

Answer 1

Bitterness, sweet, umami - all linked to G proteins - bitter & sweet receptors may be similar - umami & sweet have similar structure
(Bitter: plant alkaloid such as quinine)

Sourness - responses to hydrogen ions present in acidic solutions (anions have effect too)

Saltiness - simple sodium channel, a substance must ionize, sodium enters cell & depol

Fat - 2 receptors detect fatty acids

Question 2

Distribution of taste buds by papillae

Answer 2

(Tongue, palate, pharynx, and larynx contain 10 000 taste buds - most arranged around papillae)

Fungiform papillae: located on the anterior two-thirds of the tongue consists of up to 8 parallel folds along edge of back of the tongue (1300 buds)

Circumvallate papillae: inverted V on posterior third of tongue (250), shaped like little plateaus surrounded by moatlike trenches

Question 3

Taste buds

Answer 3

Consist of groups of 20-50 taste receptor cells - cilia located at end of each cell project through opening of taste bud (pore) into saliva that coasts tongue - 10 day lifespan

Question 4

Gustatory pathway

Answer 4

Ipsilateral

Transmitted through cranial nerves (7,9,10)
7 (anterior, facial), 9 (posterior, lingual), 10 (receptors of palate & epiglottis, vagus)
Diff flavours activates diff regions in primary gustatory area of insular cortex
Also receives thermal, mechanical, visceral, & nociceptive stimuli - palatability