Unit 2 Flashcards
Trigeminal sensations are:
irritant chemicals
Flavor sensation is an integrated sensation in the _______
brain
The trigeminal and the chemical senses are naturally bound to each other by their shared ______________, and seldom is one of them activated without an accompanying signal from one or two of the others
anatomical location
T or F: Although each bite activates the olfactory receptors (via the retronasal and orthonasal passage), the taste receptors on the tongue, as well as the trigeminal nerve endings are also activated, the sensation we obtain is not that of three individual sensation coming together, but rather that of a uniform flavor
T
Trigeminal senses are inervating the whole nasal and oral cavities which means they have nerve endings in the _____ and _________
nose and mouth
What are the 5 physical senses:
- touch
- taste
- vision
- hearing
- smell
All the physical senses also trigger _______________
memory centers
Trigeminal nerve endings can be activated by _____________ (mechanical forces and temperature) and by a huge array of chemical agents and evoke sensations of touch, pressure, temperature, pain, tingling, itching, and pungent, burning, cooling, numbing sensations
physical stimuli
__________________ is where the olfactory nerves are suspended
olfactory epithelium
What is the chemical agonist in chili peppers:
capsaicin
What is the chemical agonist in black pepper:
piperine
What is the chemical agonist in mustard oil:
allyl isothiocyanate
What is the chemical agonist in garlic:
allicin
What is the chemical agonist in ginger:
gingerols
What is the chemical agonist in tobacco plant:
nicotine
T or F: the headspace contains the aroma chemicals in the right proportions
T
Flavor sensation can be defined as a psychological interpretation of a _________________ response to a __________ stimulus
physiological
physical
Any chemical in order to elicit a physiological response in an organism, it has first to bind to a specific site in the target tissue, this site is called the ___________
receptor
The receptors for flavor active molecules are located in the _______ and ________ cavities
oral and nasal
Flavors therefore are the perception of taste, smell and _______________ caused by the different chemicals found in food.
chemestetic responses
Olfactory cells are ___________ and are situated in the upper part of the _______ cavity and their receptors perform a similar function to that of the taste cells through their own nerve fibers that transmit neural impulses from receptors directly to the olfactory bulb in the brain
neurons
nasal
Taste receptors which are found on the surface of the __________, are linked to the brain by way of ____________ which carry the nerve impulses to the brain after the _______________ are released from the taste cells, this process is initiated by the formation of the taste compound-receptor complex
taste cells
cranial nerves
neurotransmitters
Covid-19 affects sensory perceptions by:
attaching itself to the support cells which are similar to the ones found in our lungs
T or F: all taste buds have different types of taste cells
T (types 1-4)
T or F: olfactory cells/receptors are a lot more complicated than taste cells
T
Supporting cells support nerve endings going to the brain =
sustentacular cells
T or F: taste buds are found in isolation
F, they are part of a structure known as papillae
The tongue is covered with bumps called _________
papillae
Each papilla contains multiple taste buds: ________________
3000-6000 taste buds
Taste buds are filled with ___________________ - the cells that do the tasting. The tip of each gustatory cell protrudes through a pore on the surface of the tongue
gustatory cells (50-100 gustatory cells in each taste bud)
_________ carry signals from the gustatory cells to the brain
Nerves
Total taste cells = ____________________
150,000 to 600,000
The tip of each gustatory cell is covered with an assortment of __________________, which can detect a wide variety of compounds. Stimulation of any of these receptors will send a signal to the brain: bitter!
bitter taste receptors
T or F: circumvallate papillae have the highest number of taste buds
T
T or F: with age, the taste sensation decreases
T
The tongue is an organ that contains 4 types of papillae:
-circumvallate
-fungiform
-foliate
(they contain taste buds)
-filiform (can only detect the texture of food)
Circumvallate papillae contains ___________________
mucus-secreting glands
type 1 taste cells:
supporting cells
type 2 taste cells:
receptors for sweet, salty, bitter, umami
type 3 taste cells:
receptors for sour compounds
type 4 taste cells:
stem cells to regenerate new taste cells every 2 weeks
What is the name of the nerve that inervates all the taste buds and sends electrical messages to the brain
Chorda tympani nerve
The relative density of taste buds is not constant with ____; in children they are more concentrated on the tip of the tongue although they cover most of the surface; in adult there are fewer at the tip and almost none the anterior two thirds of the tongue surface
age
Food may continue to evoke some taste sensations even as it passes down the throat, since there are taste buds on the _____________, mucosa of the ___________ and the ____________. In addition, there are taste buds on the soft palate, on the mucosa of the lips and cheeks and sometimes on the floor of the mouth and even on the _______________. The movement of the tongue helps distribute taste substances to these sites. Each taste bud may contain _______ taste cells
epiglottis pharynx larynx gastrointestinal tract 50-100
Each taste bud lies beneath a ____________ on the surface of the tongue
pore opening
Many taste cells have _______________ projections (microvilli) that extend into the pit of the pore. These may bear receptor sites that interact with taste substances.
finger-like
Unlike olfactory receptors, taste receptors do not supply their own _______ to link them to the brain. Instead, ____________ grow out from the brain to the taste cells where they end in folds of the taste cell membranes. This leaves a gap or synapse across which taste information must pass. Each taste cell receives more than one ______ and each nerve innervates more than on taste cell.
nerves
cranial nerves
nerve
In ________ fifth basic taste discovered: savoriness described as umami which is conferred by glutamate
1908
___________ geneticists confirm findings about sensitivity to bitter tasting PTC and discover non-tasting is a recessive genetic trait.
1931-1932
T or F: Bitter taste sensitivity found to vary among humans
T
PTC:
phenylthiocarbamide
Specialist taste bud cells (3) TYPE 2:
- sweet
- salty
- bitter
Generalist taste bud cells (1) TYPE 3:
-sour
T or F: Type 2 and type 3 taste cells are the ones that are active in signal transduction of aroma chemicals
T
Only __ % of odorant molecules will reach the olfactory neuron
3
__________________ of the nasal cavity is responsible for detecting volatile stimuli that are present in the air or emanates from the food in the mouth.
Olfactory epithelium
Odorous compounds reach the receptors by 2 ways; one by the the nasal (__________) route and the second by the mouth (_______________) when the food is chewed
ortho-nasal
retro-nasal
___________________ on the other end are neurons and situated in the upper part of the nasal cavity and their receptors perform a similar function to that of taste cells through their own nerve fibers that transmit neural impulses from receptors directly to the ____________ in the brain
olfactory cells
olfactory bulb
Latest research shows that a complex protein produced in the olfactory mucosa acts as chemical messenger that carries lipophilic volatile compounds in the olfactory epithelium:
OBP (odorant binding protein)
When air is inhaled, the OBP is sprayed as a fine mist into the air that flows into the nose, OBP binds with the molecules in the air and carries them to the __________, the OBP-odor complex then binds to the receptor sites and elicits a response.
olfactory epithelium
Hydrophilic odorants can reach the olfactory epithelium by ___________, since mucous membrane is mainly aqueous.
free diffusion
The adult human possesses _______ smell-sensing cells or neurons. Neurons can have more than one receptor. It is estimated that there are around _______ different types of receptors capable of recognizing ___________ distinct odors
5-19 million
391
10,000
T or F: The nose detects trace contaminants in the odorants at concentrations several powers of ten below the sensitivity of GC detectors
T
Humans possess _____ glomeruli and ____ receptor types
391
__________ of each type terminate in one glomerulus
50,000
All axons of the _________ receptors of one type terminate in one corresponding glomerulus. With about 391 receptor types
50,000
G-proteins =
Guanine nucleotide-binding proteins family of proteins involved in transmitting signals from outside of the cell to the interior
The membranes of these cilia contain the olfactory receptors which are:
seven transmembrane (7TM) proteins
seven transmembrane proteins means that they possess seven _________________ that span the cell membrane to form a tunnel-like cavity in which the odorants are bound as _________________ association complexes. This process can be described as a 1:1 equilibrium, for which attractive and repulsive ______________, _____________ and the steric stress of the protein as well of the odorant in the bound state are responsible
helical domains
non-covalent
Van der Waals interactions
hydrogen bonds
T or F: cAMP is considered a second messenger
T
Coupled with the receptor protein is a G protein, abbreviation for _____________________ which consists of 3 subunits _______________________
- guanine nucleotide-binding protein
- alpha, beta, gamma
Binding of an odorant to the receptor causes the ____________ of the G protein to dissociate and to activate adenyl cyclase, which catalyzes the conversion of ATP to cAMP and pyrophosphatase.
alpha subunit
As a second messenger, cAMP binds to ion channels and __________
open them
Na and Ca ions enter the cell, and the negative membrane potential (ca. -70mV at rest) is ______________ and a signal is released along the axon of the olfactory neuron into the respective ________________ in the olfactory bulb in the brain.
decreased
glomerulus
Above a certain threshold (-50 mV) the receptor releases the ________ again and returns to the ____________ state
odorant
unbound
T or F: Generally, one odorant almost never activates only one receptor, but rather a set of odorant receptors and to a different degree as well
T
T or F: All axons of the 50,000 receptors of one type terminate in one corresponding glomerulus
T
With about 391 receptor types, humans have the same quantity of glomeruli in the olfactory bulb, the activation pattern of which is interpreted by the brain as an _________________
olfactory impression
How many potential combinations or odor impressions are possible:
5 x 10 ^117
1 aroma chemical can interact with _______ receptor
more than one
S-celery ketone elicits the _________ flavor
licorice (45ng/L)
R-celery ketone elicits the ____________ flavor
celery (9.1ng/L)
___________________ code of olfaction
Combinatorial
Lower threshold value = ___________ taste
stronger
Theories of olfaction (2):
- molecular shape
- molecular vibration
Infrared measures molecular vibrations of _____________
different bonds
Turin has proposed that when the olfactory receptor protein binds an odorant, __________________ can occur across the binding site if the vibrational mode equals the energy gap between __________________ electron levels. The electron tunneling then activates a G-protein cascade. Receptors are therefore tuned to the vibrational frequency of particular odorants, rather like cones are tuned to particular wavelengths of light.
electron tunneling
filled and empty
We don’t taste with our mouths or our noses: we taste with our ______
brain
SARS-CoV-2 binds to cell surface __________
ACE2
