L8 - The Chemical Senses

Question 1

What is the trigeminal sense?

Answer 1

Sensory nerve endings of the trigeminal nerve which innervates the skin and areas of the face which can detect irradiating substances

Question 2

What are the four aspects of taste?

Answer 2

Sweet
Sour
Omami
Bitter

Question 3

How many olfactory receptor genes are there in a human?

Answer 3

About 350

Question 4

In the olfactory system, how many types of receptor can each sensory neuron express?

Answer 4

1

Question 5

What are the characteristics of the molecules detected by the olfactory system?

Answer 5

Volatile molecules with an average mw of 150-300Da

Question 6

Outline the signalling pathway for signal transduction in olfactory sensory neurons

Answer 6

Odour binds to the gpcr which activates adenlyly cyclase two leading to an increase in cAMP opening CNG channels leading to an increase in ca and na which opens cl channels leading to depolarisation

Question 7

What is acquired anosmia?

Answer 7

Lack of sense of smell caused by trauma

Question 8

What is congenital anosmia?

Answer 8

Lack of sense of smell caused by SNPs

Question 9

Outline the basic olfactory pathway

Answer 9

Olfactory epithelium –> olfactory bulb –> olfactory cortex

Question 10

Are receptors organised at the level of the olfactory epithelium?

Answer 10

Nope

Question 11

What are pheromones?

Answer 11

Chemical signals between animals of a given species

Question 12

What does the vomeronasal organ detect?

Answer 12

Pheromones and pathogens

Question 13

What does the grüneberg ganglion detect?

Answer 13

Alarm pheromones

Question 14

What is the signal transduction pathway for the vomeronasal organ?

Answer 14

V1R –> galpha –> plc –> DAG –> TRPC2 which lets in positive ions

Question 15

What are the three types of human tastebuds?

Answer 15

Circumvallate
Foliate
Domed (unknown name)

Question 16

How is taste processed neurally?

Answer 16

The chorda tympani runs along the top of the tongue and synapses in the gustatory area and the ventral posterior nucleus of the thalamus then to the gustatory cortex
The glossophoryngael synapses at the gustatory area and at the VPN then onto the gustatory cortex

Question 17

What do tastebud cells detect in salty food?

Answer 17

Sodium

Question 18

What do tastebud cells detect in sour foods?

Answer 18

Sodium and hydrogen

Question 19

What is the receptor for umami?

Answer 19

T1R1

Question 20

What is rhe receptor for sweet?

Answer 20

T1R2

Question 21

What are the three chemical senses?

Answer 21

Olfaction
Trigeminal sense
Gustation