7.3.2 The Chemical Senses 3

Question 1

An olfactory receptor has an average survival time of just over a ____. At that point, a stem cell matures into a new olfactory cell in the same location as the first and expresses the same receptor proteins.

Answer 1

month

Question 2

The axon of this new olfactory cell then has to find its way to the ____ ____ in the olfactory bulb.

Answer 2

correct target

Question 3

Each olfactory neuron axon contains copies of its ____ ____ ____, which it uses like an identification card to find its correct partner.

Answer 3

olfactory receptor proteins

Question 4

However, if the entire olfactory surface is damaged at once by a blast of ____ ____ so that the system has to replace all the receptors at same time, many of them fail to make the correct connections, and olfactory experience does not fully recover.

Answer 4

toxic fumes

Question 5

On average, women detect ____ more readily than men, and the brain responses to ____ are stronger in women than men.

Answer 5

odours

Question 6

If people repeatedly attend to some faint odour, ____ ____ ____ gradually become more and more sensitive to it, until they can detect it in concentrations 1/10000 of what they could at the start.

Answer 6

young adult woman

Question 7

Pheromones. The ____ ____ (VNO) is a set of receptors located near, but seperate from, the olfactory receptors.

Answer 7

vomeronasal organ

Question 8

Unlike olfactory receptors, the VNO receptors are specialised to respond only to ____, chemicals released by an animal that affect the behaviour of other members of the same species.

Answer 8

pheromones

Question 9

Each VNO receptor responds to just one pheromone, in concentrations as low as one part in 100 billion. Furthermore, receptor does not ____ to a repeat stimulus.

Answer 9

adapt

Question 10

The VNO receptors continue responding strongly even after ____ ____.

Answer 10

prolonged stimulation

Question 11

In adult humans, the VNO is ___ and has no receptors.

Answer 11

tiny

Question 12

The behavioural effects of pheromones apparently occur ____.

Answer 12

unconsciously

Question 13

Exposure to these chemicals – especially chemicals from the opposite sex - alters skin temperature and other ____ responses and increases activity in the hypothalamus.

Answer 13

autonomic

Question 14

The smell of a woman’s sweat – especially if the woman was near her time of ovulation – increases the mans ____ secretions.

Answer 14

testosterone

Question 15

The smell of a males sweat causes women to increase the release of ____. Cortisol is a stress hormone, so the implication is that women are not altogether charmed by the smell of sweaty man.

Answer 15

cortisol

Question 16

____ is the experience some people have in which stimulation of one sense evokes a perception of that sense and another one also.

Answer 16

Synesthesia

Question 17

Various studies attest to the reality of synaesthesia. People reporting synaesthesia have increased amounts of ____ ____ in certain brain areas and altered connections to other areas. They also show behavioural peculiarities it would be hard to pretend.

Answer 17

grey matter

Question 18

Synaesthesia clusters in families, suggesting a genetic ____, but people are certainly not born with a letter-to-colour or number-to-colour synaesthesia.

Answer 18

predisposition

Question 19

Synaesthesia develops gradually over ___.

Answer 19

time

Question 20

When people misperceive a stimulus – as in an illusion – the synthetic experience corresponds to what the person ____ the stimulus was, not what it actually was.

Answer 20

thought

Question 21

This result implies that the synesthesia phenomenon occurs in the ____ ____, not in the receptors or the first connections to the nervous system.

Answer 21

cerebral cortex

Question 22

Furthermore, for some people, the idea of a word triggers a synesthetic experience ____ they thought of the word itself.

Answer 22

before

Question 23

One of the hypotheses of synaesthesia is that some of the ____ from one cortical area branch into another cortical area.

Answer 23

axons