Chemoreception (gustation and olfactory)

Gustation

taste - a gate keeper sense for what is and isn’t good to eat

Olfaction

smell - a gate keeper sense for what is safe to approach

Macrosmatic

smell is a primary source of information - many animals like dogs

Microsmatic

Smell is present but is not a primary source of information - humans

Anosmatic

there is either no or a very limited sense of smell

needed for smell

a sapid (water soluble) or limpoid (fat soluble) gas

How odorants reach olfactory receptors

1) they are inhaled through the nose

2) or the mouth through the retronasal opening

retronasal opening

the back of your thoat that connects your nose and throat, it works as a signal of where a smell is coming from

inhale = coming from outside

exhale = mouth = coming from inside

asomnia

a lack of smell often caused by infection or brain injury which severely limits the ability to experience flavor

taste

a physiological response of mouth receptors to chemicals that create complex patterns of neural activity from taste buds

5 tastes

sweet, salty, bitter, sour, and umami (savory) and are considered the backbone of flavor

taste buds

are not chemotopic and are spread across the tongue, they die and regenerate after a few days and sensitivity declines with age

Sensitivity of taste

1) bitter

2) salty

3) sweet

4) sour & umami

path of taste

the tongue has fungiform papilla where most taste buds are located, the taste buds are a bundle of taste cells that each have different receptors for bitter, sweet, and umami

Sour things are acids and salty things are sodium. These effect cellular biology so they don’t need receptor sites

Flavor

the complex interaction between taste and smell at least

other senses in flavor

• spice

• texture

• vision = top-down process that gives context for flavor

super tasters

have more fungiform papilla and have intense reactions to bitter flavors

subjectivity of taste

an experiment asked 7 wine experts their opinions on a class of white and red wine. they were both white wine with one glass dyed red. they described the red wine with language that had red components.

In another experiment, the same wine was poured into 2 different bottles, a high-priced wine and a low-priced wine. most subjects favored the high-priced wine despite them being the same

demonstrates that we use top-down knowledge to guide taste

orbital frontal cortex

all sensory information meets here, contains bimodal neurons that respond to more than 1 sense, combines information from multiple senses, and controls the pleasantness of flavor sensations