special senses III

Question 1

What are the five primary sensations of taste

Answer 1

• Sour = acids (HCl)
• Salty = ionized salts (NaCl)
• Sweet = sugars, glycols, alcohols, amino acids, etc
• Bitter = almost all organic substances (quinine, caffeine, strychnine, nicotine
• Umami = MSG, glutamate and other amino acids (common to protein rich foods like meat and cheese

Question 2

What cranial nerves are involved in transmitting taste info

Answer 2

• CN VII (anterior 2/3 of tongue)
• CN IX (posterior 1/3 of tongue)
• CN X (epiglottis)
• SEND INFO TO NUCLEUS OF SOLITARY TRACT –> VPM of thalamus, hypothalamus, AMYGDALA

Question 3

What nerves innervate taste on the tongue. soft palate, epiglottis esophagus

Answer 3

• Anterior 2/3 = CN VII (chorda tympani branch)
• Posterior 1/3 = CN IX
• Soft palate = CN VII (greater superficial petrosal branch)
• Epiglottis and esophagus = CN X

Question 4

describe taste receptor cells

Answer 4

• SHORT TURNOVER (every 10 days)
• NOT a neuron - releases NTs onto afferents which carry info to brain
• Only one transduction mechanism per taste cell but there can be many receptor subtypes for the same taste in one cell
• taste buds are on papillae
• only taste cells of taste buds are specialized for sensory transduction
• NOTE: T2R receptors transmit bitter taste

Question 5

describe olfactory receptor cells

Answer 5

• turnover rate = 60 days
• IS a BIPOLAR NERVE CELL = generates AP via G protein steps and depolarization of cell in response to odorant molecule bindnig
• olfactory neurons expressing same type of olfactory receptor project to same glomeruli
• an odorant might interact with several different types of olfactory receptors
• different odorants cause different patterns of electrical activity in the olfactory bulb

Question 6

gibe the bilogical roles of taste and oflaction

Answer 6

• edibility
• diet selection
• taste aversion (bait-shyness)

Question 7

describe bait-shyness

Answer 7

• if an animal feels sick after eating, assumption by the brain is that novel food is responsible
• animal loses its taste for that food
• the ability to develop a taste aversion is considered an adaptive trait or survival mechanisms that trains the body to avoid poisonous substances before they can cause harm

Question 8

define hyposmia

Answer 8

• impaired sense of smell

Question 9

anosmia

Answer 9

• absence or loss of the sense of smell
• -> specific anosmia = loss of specific smells
• -> general anosmia = complete loss of sense of smell

Question 10

define parosmia

Answer 10

disorder of the sense of smell, esp if the perception of odors that are not present

Question 11

hypogeusia

Answer 11

decreased taste sensation

Question 12

ageusia

Answer 12

absence of taste

Question 13

parageusia

Answer 13

perversion of the sense of taste/a bad taste in mouth

• -> may be side effect of some drugs (makes things taste funny)
• -> may also go along with psychological illness