7.3.1 The Chemical Senses 2

Question 1

From the NTS, information branches out, reaching the ____, the lateral ____, the ____, the ventral-posterior ____, and two areas of the cerebral cortex.

Answer 1

pons, hypothalamus, amygdala, thalamus

Question 2

One of these cerebral cortex areas, the somatosensory cortex, responds to the ____ aspects of tongue stimulation.

Answer 2

touch

Question 3

The other cerebral cortex area, known as the ____, is the primary taste cortex.

Answer 3

insula

Question 4

Curiously in taste, each hemisphere of the cortex receives input mostly from the ____ side of the tongue.

Answer 4

ipsilateral

Question 5

One connection from the insula goes to a small portion of the frontal cortex, which maintains ____ of recent taste experiences.

Answer 5

memories

Question 6

When given ____ (PTC) or 6-n-propylthiouracil (PROP), most people – referred to as tasters – taste low concentrations as bitter, but many people – referred to as non-tasters – fail to taste it except in high concentrations.

Answer 6

phenythiocarbamide

Question 7

____, have the highest sensitivity to all tastes and mouth sensations. ____ tend to have strong food preferences. On average, they like their favourite foods more than other people, and avoid their least-favourite foods more.

Answer 7

Supertasters

Question 8

The difference between tasters and supertasters depends on the number of ____ ____ near the tip of the tongue, with supertasters is having the largest number.

Answer 8

fungiform papillae

Question 9

The anatomical difference between tasters and super tasters depends partly on ____ but also on age, hormones, and other influences. Women’s taste sensitivity rises and falls with their monthly hormone cycles, when estradiol levels are high.

Answer 9

genetics

Question 10

____, the sense of smell, is the response to chemicals that contact the membranes inside the nose. For most mammals, olfaction is critical for finding food and mates and for avoiding dangers.

Answer 10

Olfaction

Question 11

Olfaction is especially important for our food selection. Much of what we call ____ or ____ is really the odour of the food.

Answer 11

taste or flavour

Question 12

Olfaction also plays an important, easily overlooked role in ____ ____. If you were exposed to the smells of other people (with no other information about them), and you related their desirability as a potential romantic partner, you would probably prefer people to smell a little different from yourself and your family members.

Answer 12

social behaviour

Question 13

Avoiding a mate who smells like your brother or sister reduces the chance of inbreeding. It also increases the probability that your children will have a wide variety of ____, because chemicals from the immune system contribute to body odours.

Answer 13

immunities

Question 14

Neurons responsible for smell are the olfactory cells, which line the ____ ____ in the rear of the nasal air passages.

Answer 14

olfactory epithelium

Question 15

In mammals, each olfactory cell has ____ (threadlike dendrites) that extend from the cell body into the mucous surface of the nasal passage. Olfactory receptors are located in this cilia.

Answer 15

cilia

Question 16

Linda Buck and Richard Axel (1991) identified a family of ____ in olfactory receptors, each of these proteins traverses the cell membrane seven times and responds to a chemical outside the cell by triggering changes in a G-protein inside the cell.

Answer 16

proteins

Question 17

The G-protein then provokes chemical activities that lead to an action potential. The best estimate is that humans have several ____ olfactory receptor proteins.

Answer 17

hundred

Question 18

Although each chemical excites several types of receptors, the most strongly excited receptor ____ the activity of the other ones, like lateral inhibition. The net result is that a given chemical produces a major response on one or two kinds of receptors and weak responses in a few others.

Answer 18

inhibits

Question 19

Each olfactory receptor responds to only a few ____. And the combined activity of two or more receptors identifies a chemical precisely.

Answer 19

stimuli

Question 20

When an olfactory receptor is stimulated, it’s axon carries an impulse to the ____ ____.

Answer 20

olfactory bulb

Question 21

Although the receptors sensitive to a particular chemical are scattered haphazardly in the nose, their axons find their way to the same ____ ____ in the olfactory bulb, such that chemicals of similar smell excite neighbouring areas, and chemicals of different smell excite more separate areas.

Answer 21

target cells

Question 22

Cells of olfactory bulb ____ the identity of smells.

Answer 22

code

Question 23

The olfactory bulb sends axons to the ____ ____ of the cerebral cortex.

Answer 23

olfactory area

Question 24

Chemicals that smell ____ to us evoke activity in neighbouring cells.

Answer 24

similar

Question 25

Olfactory receptors of vulnerable to ____ because they are exposed to the air.

Answer 25

damage