biology - recitation 4 - taste - quiz 2

10-14 days

the amount of time that taste cells are replaced. This is very fast and it is replaced because of erosion caused by food.

Vagus nerve

10th granial nerve

Ventral posterior medial (VPM) nucleus of the thalamus

Taste zone of the thalamus.

Chinese restaurant syndrome

this has symptoms of headaches, breathing problems, etc... This was thought to be caused by MSG in Chinese food however this has not been proven. Nevertheless we do know that some people are more sensitive to MSG then others.

Taste

we have 5 different tastes. This begins when chemicals dissolve in saliva of the mouth

Ionotropic receptors

*salty and sour* send ions through ______ receptors

Facial nerve

7 cranial nerve

Glossopharyngeal nerve

9 cranial nerve

Coffee, quinine

Bitter taste preferences are needed for ___ and _____

Quantity

Each papilla contains a few taste buds, and each taste bud contains taste receptors.

Taste pathway

MOUTH taste receptors ---> cranial nerves *7,9,10* ---> MEDULLA *gustatory nucleus* ---> THALAMUS VPM *nucleus of the thalamus* ----> CORTEX *gustatory cortex* + 2 CORTICAL SUBSTRUCTURES *anterior insula* and *frontal operculum* (on the inferior frontal gyrus).

Fungiform papillae

Part of the old tongue map. A single taste bud for each taste, but several hundred of this type in the same area right at the tip of tongue.

Foliate papillae

Part of the old tongue map. Has multiple taste buds which are located on sides of the tongue

Circumvallate papillae

Part of the old tongue map. Has multiple taste buds which are located on the back of the tongue

Tastes and evolution

Supertasters. This allows us to tell that *bitter* food is poisonous, *sour* is important in considered toxic and spoilt food, *salt* is important for dehydration and water and salt balance, salt it also needed to make action potential, *sugar* is for caloric value and necessary for energy (this is also why it is liked/addictive, however as these foods are becoming more regular it has been a cause for obesity), *umani* tells us there is proteins in these foods.

Ipsilateral pathway

Taste is an exception and what is sensed on the right side is being translated on the right side, and what is sensed on the left side is being translated on the left side.

Gustatory cortex, (anterior) insula cortex, frontal operculum

Taste zone of the cortex (including 2 cortical substructures).

1-100

taste buds on a papilla

50-150

taste receptors

Omnivores

taste sensitivity especially important for ______

Papilla

These are taste receptor bumps on the tongue, these receptor cells extended into *microvilli* into the *taste pore* to contact *tastants*. taste receptor bumps on the tongue which can see with the eye. Each papilla contains between 1-100 taste bud. Each taste bud contains 50-150 receptor cells which operate similarly to nerve cells.

Taste pathway

These receptors (metabotopic/ionotropic) cause a cascade of processes and eventually they release vesicles with neurotransmitters between a synapse with a nerve cell (cranial nerve cell). This message will go to the *rostral nucleus of the medulla of the solitary tract which goes into the thalamus*

Bitter

This is detected by *T2R* (*Transient 2 receptor*). Each bitter taste cell produces most types of bitter receptors. The high sensitivity may have evolved to signal toxicity. Therefore each receptor is very sensitive to a specific type of bitter molecule and cannot open another receptor unlike sugar which one receptor can open ion channel for many substances. This blocks the opening of potassium channels which means the positive charged molecule stays in the cell

Genetics

This is important and can make someone like a food group more than another. Therefore someone who likes salty food will have more salt receptors compared to someone who does not like salt.

Supertasters

This is important for evolutions. This is the idea of humans being able to taste the properties of the food and whether it is dangerous or good.

Insula cortex

taste zone of the cortex.

Metabotropic receptors

______ receptors are used for *sweet, bitter and umani*

Umami

a meaty savory flavor - detected by a type of metabotropic glutamate receptor. MSG stimulates this receptor; also receptors for all 20 dietary amino acids.

Anion

a molecule that is negatively charged, and is an indication of something being an amino acid.

Metabotropic receptors

a neurotransmitter triggers a secondary messenger usually a g protein to detach and cause another ion channel to open

Umami

a savory flavor that is considered to be the taste of proteins was discovered to be a new basic taste. This is a new taste that has been added. It allows one to tell if the food they are eating *has protein in it*. taste detection of the *carboxylate anion* (negatively charged, indication of amino acid) of *glutamic acid*, a naturally occurring amino acid common in meats, chees, etc. *MSG* is also important for ___ and it is allows for tast enhancement.

Conditioned Taste aversion

a taste that causes later illness will be avoided - conditioning over hours of delay. This is important for omnivores. The taste trace has been proved to be in the *insula*, since injecting memory blockers there prevents the conditioning. Experiment you give a rat some kind of food and you inject it with lithium chloride which causes an aversive reaction and these animals will now learn to associate the taste with the aversion they have and will now avoid the food

Sour

all acids taste sour because they release Hydrogen ions (H+). Hydrogen ions bind with the receptors, causing potassium (K+) channels to close. Potassium a positively charged ion cannot leave the cell and the membrane potential depolarizes. Therefore membrane potential becomes more positive.

Omnivore

being a herbivore and carnivore

Artificial sweeteners

can be 100,000 times sweeter than sucrose

Texture

detected by touch receptors in the mouth and allows us to identify whether a food is smooth or brittle etc..

Monosodium glutamate (MSG)

does not taste very good on its own but when added with another food it makes it taste good which means it is a food enhancer.

Microvilli

each taste receptor cell has it, it is a way to increase surface area in order to contact saliva. It is an extension structure on the taste receptor cell with folds and allow for greater surface area. This ___ extend to the taste pore.

Carnivore

eat only meat

Herbivore

eat only vegetables.

Flavor

is a combination of smell and taste. This also gives us the sensation of whether a food is "hot" (chili) or "cool" (menthol) which is detected by TRP (transient receptor protein) sensors (also in skin)

Carboxylate anion of glutamic acid

is an acid that is detected and gives the umani taste. It is considered

Taste pore

is the small space between all the microvilli.

Sweet

it is detected by a heterodimer (combination) of two *T1R* (*Transient 1 receptor*). They are composed of two non-identical sub-units. Sugar, saccharin, and other sweet-tasting substances have different shapes but all of them can bind to the sweet receptor because it has many different binding sites that can be activated. Triggers the opening of calcium channels which means that a positive ion enters the cell.

Childhood taste preference

preference of sweet is present in newborn babies, also aversion to sour or bitter. Hot taste sensations (chili) are often rejected initially. While not present at birth, preference for salty tastes appears at around four months of age

Salty

sodium (Na+) ions are transported across taste cell membranes. These sodium channels are open all the time -- unlike voltage-gated channels in the neural membrane. Therefore if you have salt it goes in which is a positive ion. Therefore membrane potential becomes more positive.

Salty, sour, sweet, bitter, umami

the five basic tastes

5

the number of basic tastes we have.

Myth

the old tongue map of sweet in the front, bitter at the back is not true and is a myth. Therefore, having these areas of the tongue is untrue, and rather a combination exist.

TRP transient receptor protein

the receptor that can identify whether a food is "hot" (chili) or "cool" (menthol) which is both in the mouth and on the skin

tongue -> papilla -> taste buds -> taste receptors -> microvilli

the tongue (from biggest to smallest)

Cranial nerves 7, 9, 10

these are the cranial nerves that the taste receptors forms synapses with. These cranial nerves will send the information to the brain.

Taste receptors

they have membrane potential that changes that causes neurotransmitter secretions (but does not cause an action potential).They are similar to non-spiking axons (on nerve cells) there is depolarization and neurotransmitter release however it does not cause an action potential or a threshold. Each receptor contains *microvilli* which are the folding of the cells membrane that increase surface area. not a normal cell, it can communicate, and cause synapses *without the using action potential*.

Basal cells

they replace the taste receptor cells when they become damaged.