Taste (7.)
Differences in Taste Sensitivity
- Genetic factors and hormones can account for some differences in taste sensitivity. - Variation in taste sensitivity are related to the number of fungiform papillae near the tip of the toungue. - supertasters have higher sensitivity to all tastes and mouth sensations in general.
The Toungue (taste organ)
- Papillae are structures on the surface of the tongue that contain the taste buds. -Each papillus may contain 0-10 taste bids - each taste bud contains approximately 50 receptor cell. - most tastebuds are located along the outside of the tongue in humans.
What are the Five classes of tastants?
- Primary tastes: Sweet, sour, salty, and bitter ~four different types of glutamate receptors -Fifth: Umami: chicken broth, -Do we have a 6th one of fat. or is it taste/texture?
Patterns and Pathways to the brain
- Receptor cells contain multiple receptor types - cells respond best to a particular taste but respond to others as well. - each receptor type causes different pattern of firing. - Receptors converge their input onto the next cells in the taste system. - The brain determines taste by comparing the responses of several types of taste neurons.
Patterns and Pathways to the brain
- Receptor cells contain multiple receptor types: -cells respond best to a particular taste but respond to others as well. -each receptor type causes different pattern of firing. - Receptors converge their input onto the next cells in the taste system. - The brain determines taste by comparing the responses of several types of taste neurons.
Taste Receptors
- Receptors for taste occur on modified skin cells called taste receptors cells. - Taste receptor cells have excitable membranes that release NTs to excite, neighboring neurons. -Taste receptors are replaced every 10-14. Short life span. -If damaged (burned tongue)- won't taste much. Compared to neurons: -taste receptor cells dont have myelin nor dendrites or axons. More like a cell body. Similar: -Can have action potentials. -Secrete some NT.
Patterns and Pathways to the Brain
- Taste nerves (chorda, tympani, 9th, 10th) project to a structure in the medulla known as the nucleus of the tractus solitarius (NTS) -subregion of medulla. - Projects info. to other parts of the brain. - Medulla has some taste receptors. - Thalamus sends info. to somatosensory cortex- for texture, up and forward. - The insula - The primary cortex - Things that make us hungry is
How do tastants affect receptor cells?
- The salt receptor permits sodium ions to cross the membrane, resulting in an Act. Pot. - Sour receptors close potassium channels when acid binds to receptors, resulting in membrane depolarization. - When coat tongue they will block K+ gates that were cracked open. K+ is stuck on inside. Making inside depolarized and act.pot. and cause gates to open and release Na. - Sweet, bitter, and Umami receptors activate a G protein that releases a 2nd messenger in the cell when a molecule binds to a receptor, resulting in membrane depolarization. - Each receptor cell may have more than one type of receptor.
Taste
-Stimulation of the receptors in the taste buds. - our perception of flavor is the combination of both tatse and smell, along with other senses. -taste and smell axons converge in the endopiriform cortex. -Food texture is sense thru activation of the somatosensory cortex.
The Taste Map
Tip= sweet Sides= sour LOOK @ MAP DAMNIT pg. 3 :)