RQ 12

The image below shows something you viewed in the taste and smell laboratory. ​a) What is the entire lump-like structure called? __________ ​b) What organ is it from? ____________ ​c) What is the part that is labeled A called? _____________ ​d) What cells are inside of (A)? ______________ and ______________.

a) A papilla from the tongue ​b) The tongue ​c) A taste bud ​d) Taste receptor cells and supporting epithelial cells

Define the following terms, as they were defined in class. ​a) Alkaloids ​b) Umami ​c) Papilla ​d) Threshold (give a general definition, not just for taste and smell) ​e) Olfactory sense ​f) Chemoreceptor

a) Alkaloids = Plant defensive molecules, some of which are poisonous. ​b) Umami = A taste sense of "meaty" flavors. ​c) Papilla = The bumps on the surface of the tongue. ​c) Threshold = The smallest amount of a stimulus that can be sensed. ​d) Olfactory sense = The sense of smell. ​f) Chemoreceptor = A sense receptor that generates a nerve signal in response to a ​ specific molecule.

How many different types of molecules can be detected by the olfactory (smell) sense? ​A) 5 ​B) 25 ​C) 350 ​D) 10,000

350

There are only five kinds of taste receptors, but there are _____ (roughly how many?) different types of olfactory receptors.

350

How many different types of molecules can be detected by the taste sense? (In other words, how many different types of taste receptors do we have?). ​A) 5 ​B) 25 ​C) 350 ​D) 10,000

5

The senses of smell and taste have all of the following in common except ​A) both sense five different types of molecules ​B) both use chemoreceptors ​C) the brain have specialized sense areas to receive their signals ​D) both transmit nerve signals directly to the brain (not via the spine)

A) both sense five different types

The correct term for the sense of smell is the ______ sense. ​A) Fragrance B) Olfactory ​C) Huelaratory ​D) Aromatic

B) Olfactory

The chemoreceptors on the tongue that are most sensitive to and respond to many types of plant toxins are the taste receptors for ​A) sweet. ​B) salty. ​C) bitter. ​D) sour.

Bitter

are sensory receptors that detect molecules (chemicals) for the senses of smell and taste.

Chemoreceptors

Given that we only have five types of taste receptors, explain how we can differentiate the tastes of thousands of different foods.

Even though we have only five types of taste receptors, we can easily taste the difference between different foods because the amounts of the five tastes are not equal in all foods. In other words, our brain interprets the unique combination of sweet, sour, bitter, salty, and umami in each food differently. Another reason foods taste different is that our sense of "taste" also includes the smell of the food, and our sense of smell has much more acuity than our sense of taste.

Which of the following is not a taste receptor type? ​A) salty ​B) fatty ​C) bitter ​D) sweet

Fatty

Explain why a person has a hard time identifying the fruit flavor of a candy when they are holding their nose shut.

Much of what we incorrectly believe to be the "taste" of a food is actually the smell of the food. This is because the sense of smell is much more keen and discerning than the sense of taste. When eating a fruit candy, the only flavors that are actually tasted by the tongue are sweet (from the sugar) and perhaps some sour (from the citric acid), but we have no taste receptors for the fruity flavor. Thus we have to rely on our sense of smell to determine what fruit flavor the candy is.

___ is the correct term for the sense of smell.

Olfactory

If you drank NaOH (the active chemical in Draino and oven cleaner...not a good idea!), which of the taste sensations would you experience? Give all answers. (Hint: NaOH turns into Na+ and OH- in your saliva. OH-- ion is a strong base)

Salty (from the Na+ ions) and bitter (from the basic OH- ions)

H+ ions (acids) cause which taste sensation? ​A) sour ​B) sweet ​C) salty ​D) bitter

Sour

If you drank HCl (a strong acid...not a good idea), which of the taste sensations would you experience? __________

Sour (from the acidic H+ ions)

In a taste receptor, the cell that detects the taste molecule is not a sensory neuron. It is a(n) ___________________ cell.

Specialized epithelial cell

The five kinds of taste receptors are____, ____, ____, ____, and ____.

Sweet ​Salty ​Sour ​Bitter ​Umami (meaty)

List the molecule(s) are detected by each of the five taste receptor types.

Sweet = Monosaccharide and Disaccharide carbohydrates ​Salty = Na+ ions ​Sour = H+/acids ​Bitter = Bases and alkaloids ​Umami = Glutamate amino acid

Taste receptors in the tongue are located in clusters called _____

Taste buds

Which of the five taste receptors has the lowest threshold? _____. Speculate on the evolutionary advantage of having this receptor type having a very low threshold

The bitter taste receptors have the lowest threshold of the five taste receptors. The evolutionary advantage of the low threshold for bitter taste is that many plant poisons are alkaloids that bind to our bitter receptors. The ability to detect low levels of plant poisons in wild plants was probably an evolutionary advantage to our ancestors.

The olfactory receptors are located in which part of the nasal cavity

The nasal epithelium

Explain why saliva is necessary to taste substances.

The taste receptors are clustered in taste buds, which are located on the sides of papillae (bumps) on the surface of the tongue. The taste buds not located at the tops of the papillae, where food tends to rest. Because they are at the sides of the papilla, the taste buds do not often come into direct contact with the food in the mouth. The saliva is responsible for carrying food molecules to the taste buds. The food molecules dissolve in the saliva, which coats the entire surface of the tongue. This carries the dissolved food molecules by diffusion to the taste buds.

The receptors for taste and for smell both detect molecules. Taste and smell receptors are therefore both classified as... ​A) Flavor receptors ​B) Alimentary receptors ​C) Oro-nasal receptors ​D) chemoreceptors

​D) chemoreceptors

The image below shows something you viewed in the taste and smell laboratory. ​a) What is cell type A? __________ ​b) What is the fuzz at the top of cell type A? __________ ​c) What is cell type B? __________ ​ ​d) What organ is this? ___

​a) An olfactory receptor cell ​b) Cilia ​c) A goblet cell ​d) The epithelium of the nasal cavity