1.30 Chemical Senses

Question 1

What type of senses are smell and taste classified as?

Answer 1

Special Visceral Senses

Question 2

What genetic components are there to why people may like or dislike some foods?

Answer 2

Some people have genes which allows them to taste certain flavours more intensely - e.g. dominant gene for the bitter taste in Brussel sprouts

Question 3

Where can taste buds be found?

Answer 3

Oral cavity, pharynx and upper part of oesophagus

Question 4

Which cranial nerves are responsible for taste?

Answer 4

VII - chordae tympani - ant. 2/3 of tongue
IX - lingual branch - post. 1/3 of tongue
X - superior laryngeal branch - epiglottis

Question 5

What is the taste map myth?

Answer 5

All areas of the tongue can taste all flavours, however some areas are more sensitive to certain flavours - back bitter, from sweet

Question 6

How many taste buds and taste cells are there on the tongue?

Answer 6

4000 taste buds - 30-100 taste cells

Question 7

What is the function of basal cells?

Answer 7

Semi-differentiated - can divide to replace taste cells

Question 8

Which substances (tastes) have the highest and lowest threshold?

Answer 8

High threshold - HCL - harmful

Low threshold - Glucose - needed

Question 9

What is the bitter, sweet and umami (amino acid) taste transduction method?

Answer 9

G protein activated - second messenger - calcium enters and calcium acts upon vesicle (CICR) - exocytosis

Question 10

What is the salt transduction method?

Answer 10

Na enters cell - causes depolarisation - na and ca enter cell - exocytosis

Question 11

What is the acids (sour) taste transduction method?

Answer 11

H ions enter cell - causes depolarisation - na and ca enter cell - exocytosis

Question 12

What is the gustatory pathway?

Answer 12

VII, IX, X - brainstem - nucleus of solitary tract - thalamus - ventroposterior - relayed gustatory cortex

Question 13

What are the cell types of the found in the olfactory epithelium?

Answer 13

Receptor neurone - bipolar 
Sustenticular cell
Basal cell 
Bowman's gland secretory cells 
Olfactory ensheathing cells

Question 14

What is the function of vomeronasal organ in animals?

Answer 14

Can detect pheromones - attraction to opposite sex

Question 15

What is the function of sustentacular cell?

Answer 15

Supporting cell for neurones and shifts mucous

Question 16

What is the smell transduction method?

Answer 16

1. odorant binds to receptor
2. activates Golf
3. alpha subunit activated in adenylyl cyclase
4. generates cAMP from ATP
5. depolarisation and ca release
6. ca opens chloride channels

Question 17

What is the function of mitral and tufted cells?

Answer 17

Miteal and tufted cells - send info to olfactory tract

Question 18

What is the function of granular cells?

Answer 18

Feedback comes through these cells, these modulate and alter other cells - act upon tufted and mitral cells - desensitisation

Question 19

What is the function of the periglomerular cells?

Answer 19

Glomeruli act upon them as well as feedback - allows cells to modulate other cells - also acts upon glomeruli

Question 20

What is the olfaction pathway in the brain?

Answer 20

1. olfactory tract
2. lateral, primary, olfactory stria
3. anterior perforated substance
4. amygdala
5. anterioir parrahyppocampal gyrus, uncul and entorhinal, and piriform area