Ch. 54 - chemical senses taste and smell

Question 1

Why do chemical senses bring up emotions

Answer 1

pass through limbic system

Question 1

Benefits of chemical senses (4)

Answer 1

1. separate undesirable/ lethal foods
2. initiate physiological response for digestion and utilization of food (i.e. salivating)
3. recognize proximity to other aimals/individuals
4. emotional and behavioral functions

Question 2

____% of taste is smell

Answer 2

50-70%

Question 3

What do the chemical receptors in taste cells sense

Answer 3

ions, compounds

Question 4

Sour taste buds recept

Answer 4

acids (hydrogen ion concentration)

Question 5

Salty taste buds recept

Answer 5

Na+

Question 6

Sweet taste buds recept

Answer 6

organic chemicals
(don’t recept a single class of chemicals)

Question 7

Bitter taste buds recept

Answer 7

organic substances, often nitrogen, alkaloids
(often toxic)

Question 8

Alkaloid bud receptors recept

Answer 8

quinine, caffeine, nicotine, plant toxins

Question 9

umami bud receptors recept

Answer 9

L-glutamate
i.e. meat, cheese

Question 10

What has the lowest threshold for taste

Answer 10

bitter (much more sensitive than all others)

Question 11

Taste blindness is usually with

Answer 11

thiorea compounds

Question 12

Taste bud make up:

Answer 12

50 epithelial cells
Contain: sustentacular cells and taste cells

Question 13

Taste cell turnover

Answer 13

fast - continually going through mitosis

Question 14

How do taste cells work

Answer 14

microvilli/taste hairs protrude outward with receptor surface for taste

Question 15

Taste nerve location

Answer 15

wraps around bodes of taste cells

Question 16

Three types of papillae:

Answer 16

1. fungiform
2. foliate
3. palate and tonsillar pillar

Question 17

Most abundant papillae

Answer 17

fungiform - more important for texture

Question 18

Amount of taste buds (age)

Answer 18

kids>adults>geriatric

Question 19

Each taste but responds to ____ taste sitmuli

Answer 19

one (of five)

Question 20

What causes change in membrane potential with taste receptor?

Answer 20

taste chemical–>taste hair –> partial loss of negative potential (graded APs)

cell becomes more positive inside w/ stimulation

Question 21

decrease in potential is proportional to

Answer 21

concentration of stimulating substance

Question 22

Taste AP pathway

Answer 22

chemical binds to protein receptor molecule on outer surface –>positie ions enter and depolarize cell

Question 23

What washes away taste stimulus?

Answer 23

Saliva (repolarizes)

Question 24

What tastes are ion specific?

Answer 24

Salty and sour salty = Na+ Sour = H+

Question 25

What tastes are second-messenger transmitter substances?

Answer 25

Sweet and bitter

Question 26

Taste adaptation

Answer 26

quick - first application is when discharge reaches peak. After, quickly adapts

Question 27

Two transmission of taste signal:

Answer 27

1. anteroro 2/3 tongue -->lingual nerve -->chorda tympani -->facial nerve -->tractus solitarius 2. Circumvallate papillae -->glossopharyngeal-->tractus solitarius

Question 28

Taste fiber (both) pathway:

Answer 28

synapse in nuclei of tractus solitarius -->2nd order neurons to ventral posterior medial nucleus of thalmus -->thirr order neurons to lower tip of postcentral gyrus in parietal cerebral cortex

Question 29

Taste reflexes

Answer 29

tractus solitarius -->superior and inferior salivatory nuclei Control secretion of saliva during ingestion/digestion

Question 30

Adaptation of taste signals (2 areas)

Answer 30

1. slight/partial at taste buds 2. complete adaptation in CNS (cerebral cortex)

Question 31

adaptation of taste signals occurs within

Answer 31

one minute

Question 32

Taste preference is based on

Answer 32

physiologic need (i.e. need salt crave salt)

Question 33

taste preference MOA is from

Answer 33

CNS

Question 34

What sense is the least well understood?

Answer 34

smell

Question 35

Olfactory membrane location

Answer 35

superior part of nostril, superior septum, superior/middle turbinate

Question 36

How is smell sensed?

Answer 36

Hairs/cilia project into mucous-->bind chemical odorants

Question 37

What are the only cells that are externally exposed?

Answer 37

Hairs/Cilia of olafactory

Question 38

What makes mucous?

Answer 38

Bowman's gland

Question 39

Stimulation of olfactory senses

Answer 39

2nd messanger mechanims

Question 40

Pathway for stimulation of olfactory senses

Answer 40

odorant to mucous-->binds to receptor proteins in cilia membrane-->transmembrane protein

Question 41

2nd messanger pathway

Answer 41

transmembrane coupled G-protein-->alpha subunit -->adenylyl cyclase -->activates cyclase-->cyclase converts ATP to cAMP-->activates gated sodium ion channel

Question 42

2nd messenger system benefit

Answer 42

multiplies excitatory effect of weak odorants (amplifies)

Question 43

resting olfactory membrane potential

Answer 43

-55 mV

Question 44

odorants depolarize to

Answer 44

-30 mV

Question 45

Olafactory receptor adaptation

Answer 45

50% in first second after stimulation

Question 46

Smell sensation classifications (7)

Answer 46

1. camphoraceous 2. musky 3. floral 4. pepperminty 5. ethereal 6. pungent 7. putrid

Question 47

Smell range

Answer 47

Small gradation in intensity but can be detected at very small concentrations (low thresshold to smell a smell)

Question 48

Olfactory bulb nerve fibers go to

Answer 48

cranial nerve I or olefactory tract

Question 49

olfactory cells have ___ and terminiate in

Answer 49

short axons and terminate in gomeruli of olfactory bulb

Question 50

glomeruli reponse

Answer 50

different glomeruli respond to different odors

Question 51

3 different pathways in CNS

Answer 51

1. very old 2. less old 3. newer

Question 52

Very old olafacotry system location

Answer 52

nuclei inmidbasal portion of brain anterior to hypothalmus. Feeds into limbic system

Question 53

very old olfactory system role

Answer 53

activating feeding systems (salivation and digestion)

Question 54

less old olafactory system location

Answer 54

prepyrform and pyrifom cortex and amygdaloid nuclei, pass through all portions of limbic system

Question 55

less old olafactory system role

Answer 55

like or dislike certain foods

Question 56

newer olfactory pathway location

Answer 56

thalmus *only one that does

Question 57

newer olfactory pathway role

Answer 57

concious analysis, higher order thinking emotions, memories, complex thoughts