taste and smell

Question 1

how do we taste (gustation)

Answer 1

Results from action of chemicals on taste buds

Question 2

how many taste buds are there

Answer 2

4,000 tase buds on tongue (also on cheeks, soft palate, pharynx, epiglottis)

Question 3

where are taste buds found

Answer 3

lie within bumps on the tongue

Question 4

what are lingual papillae

Answer 4

bumps on the tongue

Question 5

how many lingual papillae are there and name them

Answer 5

4

Filiform
- no taste buds

Foliate
- sides, buds degenerate by age 2-3

Fungiform
- concentrated at tip & sides, each has 3 buds

Circumvallate
- large, in V at rear, only 7-12 of but contain ½ all buds, around 250 each, on papilla wall, facing trench

Question 6

describe the appearance of taste buds including their cells

Answer 6

All taste buds look alike

Bulb-shaped group of cells:

Taste cells:
- gustatory
- banana shaped with hairs
- synapse with nerve

Supporting cells

Basal cells
- differentiate to taste cells

Question 7

explain microvilli in the tongue

Answer 7

Microvilli = taste hairs

Supporting cells between taste cells

Question 8

how many primary taste sensations are there

Answer 8

5

Question 9

name the primary taste sensations

Answer 9

Salty
- electrolytes

Sweet

Sour
- acids

Bitter
- alkaloids

Umami (covers most of the tongue)
- meaty amino acids, monosodium glutamate (found in processed foods)

Question 10

where are each of the primary taste sensations found on the tongue

Answer 10

bitter at back of tongue

sweet right at front tip
salty just behind sweet and up the sides

sour is nearer middle of tongue but on the sides next to salty

umami covers most of the tongue

Question 11

what must happen for us to taste food

Answer 11

Must dissolve in saliva to be tasted

Question 12

what does regional differences in taste mean

Answer 12

Certain regions of tongue more sensitive to 1 category than another

Question 13

how many main nerves are there in the gustatory pathways

Answer 13

3

Question 14

name the main nerves in gustatory pathway and describe

Answer 14

Facial nerve – picks up sweet at front of tongue

Glassopharyngaeal nerve - carry info from more posterior positions

Vagus nerve – don’t contact with the tongue more the back of throat

Question 15

what does the number of taste buds have to do with taste

Answer 15

How many taste buds you have that respond to that flavour/taste will determine how much you like that tase

Question 16

describe smell (olfaction) receptors

Answer 16

Smell receptors form a patch of epithelium
- olfactory mucosa

In roof of nasal cavity

Highly sensitive (2,000-10,000 diff odours) nat as evolved as other species such as dogs but we have other higher cognitive things that we can use as well as smell

Question 17

how many primary classes of odours are there

Answer 17

7

Question 18

name the 7 primary classes of odour

Answer 18

Camphoraceous
(moth balls smell, comes from camphor wood)

Musky (musk is used in perfumes, have heavy, deep, weedy smell)

Floral

Peppermint

Ethereal (pear drops smell)

Pungent (want to avoid, irritating, strong)

Putrid (want to avoid, smell of death, decaying, feaces)

Question 19

explain olfactory cells

Answer 19

Unlike taste cells (=
epithelial), olfactory
cells are neurons
- Olfactory receptor neurons

with olfactory hairs (immobile) and found in olfactory bulbs, not everyone has olfactory bulbs

neurons directly exposed to external environment

Only 60-day life-span

But (unlike most neurons) are replaceable

Basal cells differentiate to become olfactory cells

Question 20

Sense of smell is the closest related to what with the brain

Answer 20

memory

Such as smells of Christmas can come with that memory, or horrible smells form a stressful time can be related to that experience. So smell can come with emotional responses