5.3 Gustation

Question 1

chemical senses

Answer 1

The sense of taste depends greatly on the sense of smell. Since these two senses interpret the environment by discriminating between different chemicals, they are referred to as the chemical senses

Question 2

papillae

Answer 2

Across the surface of the tongue are different kinds of papillae present. They serve multiple functions; some are concerned with gustation, some with sensation, and some with the secretion of lingual lipase, an enzyme that helps break down fats. Whereas the papillae in the anterior region of the tongue contain just a few taste buds, the papillae found near the back of the tongue have hundreds to thousands of taste buds.

Question 3

Five basic tastes

Answer 3

salty, sour, bitter, sweet and umami - the savory taste you experience when you eat steak or other protein-rich substances. All five tastes are present across the tongue. Each of the basic taste sensations has a different from of chemical signal transduction.

Question 4

tastant

Answer 4

Food molecule. Stimulates a taste receptor cell and causes it to depolarize.

Question 5

Neural pathway gustation

Answer 5

From the axons of the taste receptors, the sensory information is transferred to the three taste pathways via the branches of cranial nerves VII, IX and X. The chorda tympani of CN VII (facial nerve) carries the taste sensory input from the tongue’s anterior two-thirds. Then, the rest of the taste sensations from the throat, palate and posterior tongue are transmitted by the branches of CN IX (glossopharyngeal nerve) and CN X (vagus nerve). From these cranial nerves, taste sensory input travels through the nerve fiber synapses to the solitary tract, the ventral posteromedial thalamic nuclei , and the thalamus. In these three locations, there are clustered neurons which respond to the same taste (sweet, sour, salty or bitter).The thalamus relays the information to the primary gustatory cortex located in the somatosensory cortex. The primary gustatory cortext is where the perception of a particular taste is processed.

Question 6

gustotopic map

Answer 6

has recently been identified in the primary gustatory cortex of the mouse brain, with considerable segregation of areas responsive to the five basic tastes. The perception of more complex tastes arises from the combination of these fundamental tastes, perhaps in the secondary gustatory cortex within the ortbitofrontal cortex.