Chapter 17 - Taste

What are the 5 primary tastes?

Sour, Sweet, Bitter, Umami, Salty.

What chemical causes the sensation of sour taste?

Hydrogen ions (H+) released from acids.

What are taste buds?

Oval bodies that contain receptors for the sensation of taste.

What types of cells are found in each taste bud?

Supporting cells, gustatory receptor cells, and basal stem cells.

What is the role of gustatory receptor cells (GRC)?

They contain gustatory microvilli that project to the external surface through the taste pore.

Where are taste buds located?

On elevations of the tongue called papillae.

What is the purpose of papillae?

To increase surface area and provide a rough texture to the upper surface of the tongue.

What are the three types of taste buds?

Vallate papillae, Fungiform papillae, Filiform papillae.

What is a tastant?

Chemicals that stimulate gustatory receptor cells.

What is the process of taste transduction?

Tastants dissolve in saliva and contact the GRC microvilli, leading to a receptor potential and synapse with sensory neurons.

How does salty taste transduction occur?

Na+ enters Na+ channels in GRC, causing depolarization and neurotransmitter release.

How does sour taste transduction occur?

H+ enters H+ channels in GRC, causing depolarization and neurotransmitter release.

How do sweet, bitter, and umami tastes transduce?

They bind to receptor proteins, activating G-protein and IP3 as a second messenger, leading to depolarization and neurotransmitter release.

Which cranial nerves contain axons that innervate the taste buds?

Facial nerve (VII), glossopharyngeal nerve (IX), vagus nerve (X).

What pathway do taste signals follow from the taste buds?

From taste buds to cranial nerves to the gustatory nucleus in the medulla oblongata, and then to the limbic system, hypothalamus, and thalamus.

What part of the brain is involved in conscious perception of taste?

The gustatory cortex of the cerebrum.