A&P 2 Flashcards: Taste and Smell

What are the 3 main cell types in the olfactory epithelium?

1. Olfactory receptors

2. Supporting cells

3. Basal cells

What is the function of olfactory receptor neurons?

Detect odorant molecules and convert them into nerve signals

What structure on olfactory receptor neurons bind odorants?

Cilia that extend into the mucus layer

Why are basal cells important?

They are cells that replace damaged olfactory receptor neurons

What produces the mucus covering the olfactory epithelium?

Olfactory glands (Bowman’s glands)

Which cranial nerve carries signals from the olfactory epithelium to the brain?

CN1 (Olfactory nerve)

What happens after an odorant binds to a receptor on olfactory cilia?

A G-Protein pathway causes depolarization of the olfactory neuron

Where do olfactory receptor neuron axons go after leaving the epithelium?

Through the cribriform plate to the olfactory bulb

Why does olfaction bypass the thalamus initially?

It has direct connection to the limbic system, links smell to emotion and memory

What 2nd messenger is used in olfactory signal transduction?

cAMP (via a g-protein coupled receptor)

Low threshold

Only a few molecules needed to detect smell

Outline the basic olfactory pathway

1. Olfactory nerves.

2. Olfactory bulbs.

3. Olfactory tracts.

What is gestation?

Sense of taste

What are the 3 type of papillae that contain taste buds?

Circumvallate (vallate), Fungiform, foliate

Does filiform papillae contain taste buds?

No

What cells make up a taste bud?

1. Gustatory cells

2. Supporting cells

3. Basal cells

What are the 5 taste modalities?

Sweet, salty, sour, bitter, umami.

Salty foods use what type of ion

NA+ (sodium)

Sour taste use what type of ion?

H+ ions enter H+ channels (Hydrogen)

Which taste modalities use g-protein mediated receptors?

Bitter, sweet and umami

Which cranial nerves carries taste from the anterior 2/3rd of the tounge?

CN VII(Facial nerve)

Which cranial nerve carries taste from the posterior 1/3rd of the tounge?

CN IX (glossoparyngeal nerve)

Which cranial nerve carries taste from the epiglottis?

CN X (vagus nerve)

Outline basic gustatory pathway.

1. Taste receptor

2. 2. Cranial nerves (VII, IX, X)

3. Brainstem

4. Thalamus

5. Gustatory cortex in the cerebral cortex

What is circumvallate (vallate) papillae

Large v-shaped row of taste buds in the back of the mouth

What is the purpose of homeostatic taste?

Chemoreceptors allow us to taste chemicals before we swallow them to protect us from ingesting something harmful.

List the steps of gustation sensation

1. Receptor potential is generated by tastants (gustatory cells)

2. If threshold is met action potential is generated

3. Action potential first going to go to medulla then thalamus

4. Thalamus sends info to gustatory area of brain (parietal lobe)

What are the 3 steps to how olfactory receptors detect gas molecules

1. Gas molecules dissolve into mucus of olfactory epithelium

2. Chemicals from the gas molecules bind to odorant

3. Receptor potential is generated

What are the 4 steps to the olfactory pathway?

1. Receptor potential is generated by odorant receptor

2. Action potential once threshold is met

3. Action potential passes through olfactory nerves in olfactory bulb

4. Action potential travels through olfactory tract into the thalamus (sensory info is sent to the olfaction area of the brain)

Where is fungiform taste buds located?

It’s scattered over the tounge.

Where is foliate taste buds located?

Sides of tounge.