CHAPTER 16: Chemical Senses

Question 1

what are the five basic taste sensation?

Answer 1

salty, sour, sweet, bitter, and umami (meaty, brothy, savoury; generally associated with additives like MSG).

Question 2

define taste and olfaction

Answer 2

taste: the chemical sense that occurs when molecules enter the mouth in solid or liquid form and stimulate the receptors on the tongue

olfaction: the sense of smell -> usually results in the stimulation of receptors in the olfactory mucosa

both taste and olfaction can be thought as the “gate-keepers” because we choose what foods to eat and avoid

Question 3

what are harmful (poisonous) substances that taste bitter?

Answer 3

cyanide, arsenic, and strychnine

Question 4

what is papillae and what are the four types of palillae?

Answer 4

papillae are the ridges and valleys on the tongue, some that contain taste buds.

1. filiform papillae are shaped like cones and cover the the entire surface of the tongue. They do not contain taste buds
2. fungiform papillae are shaped like mushrooms and are found at the tips and sides of the tongue
3. foliate papillae are series of folds along the back of the tongue on the sides
4. circumvallate papillae are shaped like flat mounds surrounded by a trench and are found at the back of the tongue

Question 5

taste buds, taste cells, and receptors cells

Answer 5

taste buds are contained on the papillae on the tongue -> there are about 10,000 of them. Each taste bud contains 50-100 taste cells that protrude into the taste pore

taste cells make up taste buds, and there are a number of cells for each bud and the tip of each one sticks out into a taste pore

receptor cells are sites located on the tips of taste cells and there are different types of receptor cells for different chemicals. Chemicals contacting the the sites cause transduction by affecting the ion flow into the cell membrane of the taste cell

Question 6

what are across fiber patterns?

Answer 6

another name for population coding

the pattern of nerve firing that a stimulus causes across a number of neurons

Question 7

what is amiloride?

Answer 7

a substance that blocks the flow of sodium into taste receptors

Question 8

what is PTC? What do you call people who can taste it vs not? Why can some people taste it?

Answer 8

PTC is a bitter substance that people with higher density of taste buds can usually taste, and specialized receptors. People who can taste it are called “tasters” and people who can’t are called “tasters”

Question 9

what is anosmia?

Answer 9

anosmia is the loss of smell due to injury or infection, such as food poisoning or failure to detect fire or natural gas leaks.

our lives are enhaced by our olfactory system and become a little bit more dangerous when it is damaged as it can alert us to danger

Question 10

what does it mean to be microsmatic? who is usually microsmatic?

what is macrosmatic?

Answer 10

having a weak sense of smell - usually occurs in animals, such as humans, in which the sense of smell is not crucial for survival

macrosmatic is a keen sense of smell - usually an important survival sense. Applies especially to dogs

Question 11

what is detection threshold for odors? what is one method for finding this threshold?

Answer 11

detection threshold is the lowest concentration at which an odorant can be detected.

A method for finding detection thresholds is the forced-choice method. The person selects one of two choices, one weak odorant and one no odorant and must select the trial on which the odorant was selected

Question 12

what is alzheimer’s disease and how is the olfactory system involved in diagnosing it?

Answer 12

alzheimer’s disease is the serious loss of memory and other cognitive functions that is often preceded by mild cognitive impairment

loss of olfactory systems begins decades before the occurance of clinical alzheimer’s symptoms like memory loss. Measuring olfactory function is a way of achieving an early diagnosis of alzheimer’s

Question 13

what are odor objects and provide examples

Answer 13

odor objects is the source of an odour

ex. rose, dog, bacon, oranges

Question 14

olfactory mucosa, olfactory bulb, and olfactory receptor neurons

Answer 14

the olfactory mucosa is a dime-sized region on the roof of the mouth just below the olfactory bulb

the olfactory bulb is the structure that recieves signals directly from the olfactory receptors and contains glomeruli

olfactory receptor neurons are sensory neurons located in the olfactory mucosa that contain the olfactory receptors. Similar to how rods and cones only contain one type of visual pigmentation, the olfactory receptor neurons only contain one type of olfactory receptor

Question 15

what are glomeruli and where are they found?

Answer 15

glomeruli are small structures in the olfactory bulb that recieve signals from similar olfactory receptor neurons. One function of each glomerulus is to collect information about small groups of oderants

Question 16

where are the olfactory areas and what cortexes do they correspond with?

Answer 16

the primary olfactory area is a small area under the temporal lobe that recieves signals from globeruli in the olfactory bulb. It is also known as the piriform cortex

the secondary olfactory area is an area in the frontal lobe, near the eyes, that recieves signals originating in the olfactory receptors. It is also known as the orbitofrontal cortex

Question 17

what is the proust effect?

what are the unlocked memories called?

Answer 17

the proust effect, created by Marcel Proust, is the idea that taste and olfaction can trigger memories. He discovered it when the taste and smell of a tea-soaked madelaine cookie unlocked some of his childhood memories.

1. Memories were not unlocked by just seeing the cookie, but by tasting it
2. the memory was vivid and transported Proust back to his childhood/past

these unlocked memories through the Proust Effect are called odor-evoked autobiographical memories. These can be triggered by smells such as crayons or baby powder

Question 18

what is oral capture

Answer 18

the condition in which sensations from both olfaction and taste are percieved as being located in the mouth