Chemical Senses: Olfaction and Taste

Question 1

Where are the cell bodies of olfactory receptor cells

Answer 1

Olfactory Epithelium, under Cribiform Plate

Question 2

List all components of the Olfactory Processing Pathway

Answer 2

Olfactory Receptors –> Olfactory Nerve –> Olfactory Bulb –> Olfactory Tract –> Pyriform cortex/Olfactory Tubercle –> Amygdala –> Orbitofrontal cortex and Hypothalamus
(Olfactory Tract also leads to Entorhinal Cortex which leads to Hippocampus)

Question 3

List the Stimulus Transduction Sequence

Answer 3

1. Odorant delievered to epithelium along airstream
2. Odorant diffuses through mucus to reach cilia
3. Odorant interacts with receptor protein
4. Binding to receptor DEPOLARIZES receptor potential
5. Linkage increases cAMP, binds to ion channel, opens it, depolarizes rest of cell

Question 4

Are Olfactory Neurons Broadly or Narrowly Tuned

Answer 4

Broadly

Question 5

What type of receptor do odorants bind to?

Answer 5

G protein coupled receptors - 7 transmembrane domains

Question 6

How deep does Schiedo take it?

Answer 6

The Deepest.

Question 7

Where is the Olfactory Bulb in relation to the rest of CNS

Answer 7

OB is most rostral part of CNS

Question 8

Describe the laminar organization of the olfactory bulb

Answer 8

Glomerular layer, External plexiform layer, mitral cell layer, granule cell layer

Question 9

what are mitral and tufted cells?

Answer 9

Relay neurons projecting to the olfactory cortex

Question 10

What is the function of periglomerular and granule cells?

Answer 10

Inhibitory interneurons, cluster around neutropils called glomeruli, the functional unit of the bulb

Question 11

What are soft palate taste buds most receptive to?

Answer 11

Sweetness

Question 12

Describe the Taste Apparatus

Answer 12

Taste buds are on protrusions named Papillae, pear shaped ball of cells with 50-100 receptor cells and basal cells

Question 13

Do taste stimuli depolarize or hyperpolarize the cells?

Answer 13

Depolarize

Question 14

Describe the salt ionic transduction mechanism

Answer 14

salt binds to amiloride-sensitive sodium ion channels

Question 15

Describe the acid ionic transduction mechanism

Answer 15

acids bind to H+ sensitive cation channels

Question 16

What taste types use receptor mediated transduction?

Answer 16

sweet, bitter, amino acids (Umami)

Question 17

What is the Pattern Code

Answer 17

One axon fires in many different patterns according to stimuli to give perception of different tastes

Question 18

Why is CN V referred to as the “Common Chemical Sense”

Answer 18

because it conveys oral irritation information